Sound Practices Mailing List Files - Volume 2
=========================================================================
From: "Rice, Doug" <RICEDA@phibred.com>
Subject: [JN] Baby-O
Date: Thu, 16 Mar 2000 09:30:33 -0600
Source: Sound Digest Archive v02.n485
Could someone copy Gordon's Baby-O article from SP#9 for me? I can't get a
back issue from Joe.
A gift of appreciation will be sent.
Or, if anyone has a spare issue 9, I would love to buy it!
Thanks in advance,
Doug Rice
=========================================================================
From: rcjones1@mmm.com
Subject: [JN] Baby on the way
Date: Tue, 18 Sep 2001 13:50:32 -0500
Source: Sound Digest Archive v02.n977
All,
As an "infrequent regular" on the list I want to let everyone know that my
wife and I are expecting our first child early next year.
Oh and my 76->71a->6B4G amp sounds great!
Richard&Joyce
=========================================================================
From: Steven S <steven@403forbidden.net>
Subject: Re: [JN] Baby on the way
Date: Tue, 18 Sep 2001 17:16:46 -0400 (EDT)
Source: Sound Digest Archive v02.n977
congrats,
I'm not the daddy type so I work too much, brew beer and build too much
crap (amps, speakers, hot rods) for my own good but.. all my friends are
doing it! Just dont go naming him/her blackie or joe!
On Tue, 18 Sep 2001 rcjones1@mmm.com wrote:
> All,
>
> As an "infrequent regular" on the list I want to let everyone know that my
> wife and I are expecting our first child early next year.
>
> Oh and my 76->71a->6B4G amp sounds great!
>
> Richard&Joyce
>
=========================================================================
From: "Phil Sieg" <triodelover@home.com>
Subject: Re: [JN] Baby on the way
Date: Tue, 18 Sep 2001 17:37:07 -0400
Source: Sound Digest Archive v02.n977
Congrats to both of you. Here's wishing your wife a complication-free
pregnancy, an easy delivery, and both of you a healthy, joyful offspring.
Best,
Phil
- ----- Original Message -----
From: <rcjones1@mmm.com>
To: <sound@lists.io.com>
Sent: Tuesday, 18 September, 2001 14.50
Subject: [JN] Baby on the way
> All,
>
> As an "infrequent regular" on the list I want to let everyone know that my
> wife and I are expecting our first child early next year.
>
> Oh and my 76->71a->6B4G amp sounds great!
>
> Richard&Joyce
>
>
=========================================================================
From: "Phil Sieg" <triodelover@home.com>
Subject: Re: [JN] Baby on the way
Date: Tue, 18 Sep 2001 17:59:17 -0400
Source: Sound Digest Archive v02.n977
Howsa 'bout David Harold Thomas Jones. Or Deborah Hillary Theresa Jones.
Either way, the kid would be DHT Jones ;-).
Phil
- ----- Original Message -----
From: <rcjones1@mmm.com>
To: "Phil Sieg" <triodelover@home.com>
Sent: Tuesday, 18 September, 2001 17.38
Subject: Re: [JN] Baby on the way
>
> Thank you for your best wishes! I hope it goes well. How about "triode"
> as a name?
>
> :)
>
> Richard
>
>
>
>
>
> "Phil Sieg"
> <triodelover@ho To: Richard - BIE C.
Jones/US-Corporate/3M/US@3M-Corporate
> me.com> sound@lists.io.com
> cc:
> 09/18/01 04:37 Subject: Re: [JN] Baby on the
way
> PM
>
>
>
>
>
>
>
> Congrats to both of you. Here's wishing your wife a complication-free
> pregnancy, an easy delivery, and both of you a healthy, joyful offspring.
>
> Best,
>
> Phil
> ----- Original Message -----
> From: <rcjones1@mmm.com>
> To: <sound@lists.io.com>
> Sent: Tuesday, 18 September, 2001 14.50
> Subject: [JN] Baby on the way
>
>
> > All,
> >
> > As an "infrequent regular" on the list I want to let everyone know that
> my
> > wife and I are expecting our first child early next year.
> >
> > Oh and my 76->71a->6B4G amp sounds great!
> >
> > Richard&Joyce
> >
> >
>
>
>
>
>
>
=========================================================================
From: Nicholas McKinney <nick@lambdacoustics.com>
Subject: [JN] Baby Photos
Date: Thu, 11 Nov 1999 18:58:28 -0500
Source: Sound Digest Archive v02.n330
Hi guys, I took my baby to the photo shop to get a few pictures taken, hope
you like.
http://www.lambdacoustics.com/products/tubedrivers.html
cya
Nick
Nicholas McKinney
Lambda Acoustics Inc.
www.lambdacoustics.com
=========================================================================
From: Bjorn Kolbrek <bjornk@studpors.hit.no>
Subject: [JN] Back again
Date: Wed, 22 Aug 2001 14:45:37 +0200
Source: Sound Digest Archive v02.n953
Hello folks!
I'm back on the list again. To all I met at the ATF: Thanks for a great time
and many inspiring ideas. Not much done yet, but I work on it. I also hope
to update my homepage soon with pictures and shematics.
Regards,
Bjørn
- -------------------------------------------------
__/\__
/ ____ \ Bjørn Kolbrek
| | || | |
| | || | | bjornk@studpors.hit.no
| | || | | http://www.geocities.com/la1zka
| | || | |
| |____| |
| /||||\ |
--------
| | | |
- -------------------------------------------------
=========================================================================
From: Steven <stevensl@mindspring.net>
Subject: [JN] Back issue of speaker builder anyone?
Date: Tue, 14 Mar 2000 18:59:54 -0500 (EST)
Source: Sound Digest Archive v02.n483
Looking for a copy of Speaker Builder 97 & 98
on the snail horn and snail II horns..
hate to spend $64 bucks for 2 articles...
;-)
steven
=========================================================================
From: "Bert Doppenberg" <lowther@wxs.nl>
Subject: [JN] Backloading Lowther
Date: Thu, 27 May 1999 10:11:27 +0200
Source: Sound Digest Archive v02.n153
Hi Johari, all,
>Well, I'm not sure what this 250Hz frequency "dip" sounds like but I sure
>would appreciate any fellow Lowther fan on this list, who have had
>experience with the MAU IVs, to show me how to look out for this "dip".
>Anyway, I did noticed that kickdrums on the MAU IVs do sounded a wee bit
>"recessed" and "mused". Is this the frequency "dip" we're talking about?
I have the Mauhorn driven by the DX4's. The low-mids are a bit shy compared to the hights
and low frequencies. Classical music does sound not bad at all. I like the Mauhorn most
(except for the Carfrae horns!) for single driver horns I've heard. The Medallion does do
a better job (more colouration though) in the low-mids but lacks a bit in bass extension.
It's always a compromise using a backloaded horn with Lowther...
>I'm also curious to know how the DX3/DX4 driver sounds in the MAU IVs. Will
>the 150Hz front horn "except" the DX4 driver in this application? I was
>told that the PM4A is the best option.
The DX4 is a very good candidate for the 150 front horn approch. I should try the front
horn on the Mau horns if i can find the time...
Regards,
Bert,
- ------
E-mail:
Business : BD-Design@lowther.nl
Private : BD@lowther.nl
Lowther Club Holland : LCH@lowther.nl
Homepage : http://www.lowther.nl
Tel./Fax: (0341) 254500 Mobile: (06) 51242990
=========================================================================
From: "johari yip" <hfyip@pacific.net.sg>
Subject: [JN] Re: Backloading Lowther
Date: Thu, 27 May 1999 22:32:54 +0800
Source: Sound Digest Archive v02.n153
- ----- Original Message -----
From: Bert Doppenberg <lowther@wxs.nl>
To: Johari Yip <hfyip@pacific.net.sg>; <sound@lists.io.com>
Sent: Thursday, May 27, 1999 4:11 PM
Subject: Backloading Lowther
>
Bert, everyone
>
> I have the Mauhorn driven by the DX4's. The low-mids are a bit shy
compared to the hights
> and low frequencies.
The same conclusion as mine proving that it's not the cause of a specific
driver but rather the horn design shortcoming.
Classical music does sound not bad at all. I like the Mauhorn most
> (except for the Carfrae horns!) for single driver horns I've heard. The
Medallion does do
> a better job (more colouration though) in the low-mids but lacks a bit in
bass extension.
> It's always a compromise using a backloaded horn with Lowther...
I have been listening to the Acousta 115 with the 7A previously and found
the MAU IVs with the same drivers sounded thinner in the lower mid and mid
as compared to the Acousta. Colouration of the Acousta enclosure maybe?
>
>
> The DX4 is a very good candidate for the 150 front horn approch. I should
try the front
> horn on the Mau horns if i can find the time...
Great. Keep me in the loop, Bert. Should be interesting
Johari
=========================================================================
From: "Robert Lamarre" <rlamarre@rlacoustique.com>
Subject: RE: [JN] Backloading Lowther
Date: Thu, 27 May 1999 19:28:26 -0000
Source: Sound Digest Archive v02.n154
Bert,
I agree with you on all accounts about the shiness in the low mids on the
Mau IV and "Extra" low mids in the Medaillons.
But as you put it, it is really coloration ( from the box, I might add)
How are your impressions on the sound of the Carfrae. They look real nice,
thats for sure.
Cheers,
- -------- Robert Lamarre --------
- ----- RL Acoustique, Canada ----
- ------ Ph/Fx: 450-653-3461 -----
- --- rlamarre@rlacoustique.com --
- ----- www.rlacoustique.com -----
- -----Original Message-----
From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
Behalf Of Bert Doppenberg
Sent: Thursday, May 27, 1999 8:11 AM
To: Johari Yip; sound@lists.io.com
Subject: [JN] Backloading Lowther
Hi Johari, all,
>Well, I'm not sure what this 250Hz frequency "dip" sounds like but I sure
>would appreciate any fellow Lowther fan on this list, who have had
>experience with the MAU IVs, to show me how to look out for this "dip".
>Anyway, I did noticed that kickdrums on the MAU IVs do sounded a wee bit
>"recessed" and "mused". Is this the frequency "dip" we're talking about?
I have the Mauhorn driven by the DX4's. The low-mids are a bit shy compared
to the hights
and low frequencies. Classical music does sound not bad at all. I like the
Mauhorn most
(except for the Carfrae horns!) for single driver horns I've heard. The
Medallion does do
a better job (more colouration though) in the low-mids but lacks a bit in
bass extension.
It's always a compromise using a backloaded horn with Lowther...
>I'm also curious to know how the DX3/DX4 driver sounds in the MAU IVs. Will
>the 150Hz front horn "except" the DX4 driver in this application? I was
>told that the PM4A is the best option.
The DX4 is a very good candidate for the 150 front horn approch. I should
try the front
horn on the Mau horns if i can find the time...
Regards,
Bert,
- ------
E-mail:
Business : BD-Design@lowther.nl
Private : BD@lowther.nl
Lowther Club Holland : LCH@lowther.nl
Homepage : http://www.lowther.nl
Tel./Fax: (0341) 254500 Mobile: (06) 51242990
=========================================================================
From: "Johari Yip" <hfyip@pacific.net.sg>
Subject: Re: [JN] Backloading Lowther
Date: Fri, 28 May 1999 09:14:34 +0800
Source: Sound Digest Archive v02.n154
- ----------
> From: Robert Lamarre <rlamarre@rlacoustique.com>
> To: Bert Doppenberg <BD@lowther.nl>; Johari Yip <hfyip@pacific.net.sg>;
sound@lists.io.com
> Subject: RE: [JN] Backloading Lowther
> Date: Friday, May 28, 1999 3:28 AM
>
Robert, Bert and all in Joeland,
>
> I agree with you on all accounts about the shiness in the low mids on the
> Mau IV and "Extra" low mids in the Medaillons.
> But as you put it, it is really coloration ( from the box, I might add)
Bob, I remembered sometimes back during our short email exchanges where you
give some hints on how to further improve on the MAU IV shy lower mid
region and one of they is to enlarge the chamber behind the driver by
cutting holes into the bottom reflector separating a void space from the
chamber. Now my question is, will placing an appropriate "spacer" between
the driver and the enclosure effectively enlarge the chamber as well? If
so, how thick such this spacer be? I have thought of using a piece of 1"
plywood as "spacer". Appreciate your feedback.
Johari
>
> How are your impressions on the sound of the Carfrae. They look real
nice,
> thats for sure.
Yes, I'm interested to know as well.
Johari
=========================================================================
From: "Bert Doppenberg" <lowther@wxs.nl>
Subject: Re: [JN] Backloading Lowther
Date: Sat, 29 May 1999 11:48:21 +0200
Source: Sound Digest Archive v02.n157
Hi Robert,
>I agree with you on all accounts about the shiness in the low mids on the
>Mau IV and "Extra" low mids in the Medaillons.
>But as you put it, it is really coloration ( from the box, I might add)
>
>How are your impressions on the sound of the Carfrae. They look real nice,
>thats for sure.
These are great! due the cornere loading, the common low-mid dip is almost gone but the
length of the horn is a bit too long. If you don't listen to the music but to technical
aspects of the system, then the low and low-mids are coming a bit too late in time. For
example, the 'kickdrum" mentioned earlyer doesn't give the "kick" compared to my Oris with
Onken-like subs do.
Bert,
- ------
E-mail:
Business : BD-Design@lowther.nl
Private : BD@lowther.nl
Lowther Club Holland : LCH@lowther.nl
Homepage : http://www.lowther.nl
Tel./Fax: (0341) 254500 Mobile: (06) 51242990
=========================================================================
From: "Larry D. Moore" <l-moore@onu.edu>
Subject: [JN] Back on Line!
Date: Sun, 17 Oct 1999 18:00:39 -0400
Source: Sound Digest Archive v02.n304
Just got my new modem up and working here at home. What a bitch! These
things get tuffer every time.
L.D. Mooore
=========================================================================
From: "Thomas Sylvester" <TRS@carlsmith.com>
Subject: [JN] Back on line
Date: Wed, 19 Apr 2000 17:02:31 -1000
Source: Sound Digest Archive v02.n525
I've been off-line since 4/11 (a whale swam over the cable between Hawaii and LA). Can anyone tryin
g to correspond on the OPT headphone amp design please resend?
Thanks, Tom Sylvester trs@carlsmith.com
=========================================================================
From: "Epstein, Jeremy" <JEpstein@ndbcap.com>
Subject: [JN] RE: backwards amp
Date: Fri, 12 Jan 2001 14:37:39 -0500
Source: Sound Digest Archive v02.n783
Conrad says:
>>>>>I cannot believe that someone hasn't suggested it yet, but why
not
+__ spkr___+
) |
) |
+----------+--- *GND*
) |
auto ) |
former ) |
| ----- DC
PLATE --- SUPPLY
+--GRID | #3
| CATH |
| | |
| +----------+ Note *negative* wrt GND
| |
<<<<<
Cool!
>>>Which does take some extra wire:
If we've got 4k:4ohm step down that's sqrt(1000) turns or about
30:1
So the "overhead" of getting the DC out of the spkr is about 3%.<<<<
I'm not sure what this part means. Are you talking about the difference in
ratio between having the secondary contained between the ends of the total
winding vs. having it hang off of one end? Trying to keep up here.
Would this output arrangement invert phase?
>>>>But, the real question is: if we have to wire the "speaker" part
of the "auto"former with a separate gauge to the "plate" part,
how is this different to a conventional transformer?<<<
Well, you would not need an insulation (dielectric) rated for the difference
between the plate voltage and ground, just the AC swing of the output is
all, I guess. And I'm assuming that the coupling between two pieces of one
winding will be closer than between two seperate windings, but as I think
about your challenging question I find I have no basis for that assumption.
One thing: having the speaker section grounded and suppose we wind it
outermost, then we have a built in shield, don't we? But that's no different
either, is it?
- -j
=========================================
Jeremy Epstein........jepstein@ndbcap.com
=========================================
=========================================================================
From: Conrad Drake <conrad@directwest.iinet.net.au>
Subject: [JN] Re: backwards amp
Date: Sat, 13 Jan 2001 14:14:18 +0800
Source: Sound Digest Archive v02.n783
"Epstein, Jeremy" wrote:
> Conrad says:
> +__ spkr___+
> ) |
> ) |
> +----------+--- *GND*
> ) |
> auto ) |
> former ) |
> | ----- DC
> PLATE --- SUPPLY
> >>>Which does take some extra wire:
> >>If we've got 4k:4ohm step down that's sqrt(1000)
> >> turns or about 30:1 So the "overhead" of getting
> >> the DC out of the spkr is about 3%.<<<<
>
> I'm not sure what this part means. Are you talking about the difference in
> ratio between having the secondary contained between the ends of the total
> winding vs. having it hang off of one end? Trying to keep up here.
Correct:
the 30:1 autotransformer needs 29 x N turns of thin wire and one
x N of thick.
the "extended" autotransformer now needs 30 x N turns of thin.
Interestingly, in theory, (from the viewpoint of fixed, if
relative, DCR) the one x N of thick wire "needs" the same cross
sectional area as the 30 x N turns of thin wire.
The impression that I get is that, relatively speaking, the HT
winding is over-provisioned: that is the ratio of gauges used
does not match the turns ratio.
Eg: our 30:1 transformer might use 60ga for the HT, and 2 ga for
the LT. Both of which are outside the "normal" range one sees.
Can anyone who actually winds transformers comment on whether
this reflects (commercial) reality? Or point out the massive
hole in my (zero reference to the manual) theory?
> Would this output arrangement invert phase?
Yes.
> >>>>But, the real question is: if we have to wire
> >>>>the "speaker" part of the "auto"former with a
> >>>>separate gauge to the "plate" part, how is
> >>>>this different to a conventional transformer?<<<
>
> Well, you would not need an insulation (dielectric) rated for the difference
> between the plate voltage and ground, just the AC swing of the output is
> all, I guess. And I'm assuming that the coupling between two pieces of one
> winding will be closer than between two seperate windings, but as I think
> about your challenging question I find I have no basis for that assumption.
It's funny - but my knee jerk reaction would be to wind the
speaker coil first (innermost) and then the HT around the
outside.
I'm afraid I'm not very good at visualising nearfield magnetic
coupling: I'm used to dealing with either far field or capactive
coupling.
Yours,
Conrad Drake
=========================================================================
From: Douglas Purl <dcp@selway.umt.edu>
Subject: [JN] RE: backwards amp
Date: Sat, 13 Jan 2001 14:19:51 -0700 (MST)
Source: Sound Digest Archive v02.n783
I can't recall who now, but one of the late and legendary electroluminati
used to take delight in drawing up circuits in a manner that confused his
colleagues. Maybe we need a competition here.
Doug Purl
=========================================================================
From: "Dave Slagle" <dslagle@earthlink.net>
Subject: Re: [JN] Re: backwards amp
Date: Sat, 13 Jan 2001 17:14:15 -0500
Source: Sound Digest Archive v02.n783
i think martin nailed it... the extended autoformer is nothing different
than a conventional transformer, and the PS makes it look like something
else... look at an input trannie with one side of each winding grounded...
same animal.. (except for the inverting)
> Interestingly, in theory, (from the viewpoint of fixed, if
> relative, DCR) the one x N of thick wire "needs" the same cross
> sectional area as the 30 x N turns of thin wire.
>
> The impression that I get is that, relatively speaking, the HT
> winding is over-provisioned: that is the ratio of gauges used
> does not match the turns ratio.
this goes to the whole thing martin brought up a while ago... the idea of
cheating one or the other, but when it comes down to it, the AC signal is
what dictates losses, and requires by "rule" the primary and secondary have
the same X-sectional area (neglecting losses) this holds try for power
trannies, but when we do bring into consideration the se primary also
carries DC and its associated losses... the ideas of cheating come into
play.
> Eg: our 30:1 transformer might use 60ga for the HT, and 2 ga for
> the LT. Both of which are outside the "normal" range one sees.
it seems this would be an output, or power transformer, at which point i
would think the 50/50 rule should hold...i guess the arguemnet could be made
for cheating either way, but in the case of an IT that delivers voltage...
maybe a little beefier primary would cut losses on one side, without much
penalty on the other?
i guess a bifilar IT would be the test bed... use say #34 on each side for a
matched one, and then #33 and #35 for the other... you could then reverse
the cheating from primary to seconadary... and see what happens.
hell wind it trifilary and this will allow you the option of trying some
current cancellation with the third winding, just terminate it with some CC
diodes, or an active source... or you could parallel the odd winding with
one side or the other.
dave
=========================================================================
From: "Danielak, Robert M" <robert.m.danielak@lmco.com>
Subject: RE: [JN] RE: backwards amp
Date: Mon, 15 Jan 2001 10:04:10 -0500
Source: Sound Digest Archive v02.n783
like i said, it's just a matter of where you put the grounds...:)
good one conrad!
and i guess this is not much different from a standard
transformer (assuming you would normally ground the secondary
- - i generally do not...).
so i guess i'm also not sure what the benefit of an autoformer
output stage is (although i do so enjoy these thought experiments).
however, there may be some distinct differences with respect to
voltage gradients, and capacitances, depending upon how you wind and connect
the autoformer...
> ----------
> From: Epstein, Jeremy[SMTP:JEpstein@ndbcap.com]
> Sent: Friday, January 12, 2001 2:37 PM
> To: 'conrad@directwest.iinet.net.au'; Joenet (E-mail)
> Subject: [JN] RE: backwards amp
>
> Conrad says:
>
> >>>>>I cannot believe that someone hasn't suggested it yet, but why
> not
>
> +__ spkr___+
> ) |
> ) |
> +----------+--- *GND*
> ) |
> auto ) |
> former ) |
> | ----- DC
> PLATE --- SUPPLY
> +--GRID | #3
> | CATH |
> | | |
> | +----------+ Note *negative* wrt GND
> | |
>
>
> <<<<<
>
>
> Cool!
>
>
> >>>Which does take some extra wire:
> If we've got 4k:4ohm step down that's sqrt(1000) turns or about
> 30:1
> So the "overhead" of getting the DC out of the spkr is about 3%.<<<<
>
> I'm not sure what this part means. Are you talking about the difference in
> ratio between having the secondary contained between the ends of the total
> winding vs. having it hang off of one end? Trying to keep up here.
>
> Would this output arrangement invert phase?
>
> >>>>But, the real question is: if we have to wire the "speaker" part
> of the "auto"former with a separate gauge to the "plate" part,
> how is this different to a conventional transformer?<<<
>
> Well, you would not need an insulation (dielectric) rated for the difference
> between the plate voltage and ground, just the AC swing of the output is
> all, I guess. And I'm assuming that the coupling between two pieces of one
> winding will be closer than between two seperate windings, but as I think
> about your challenging question I find I have no basis for that assumption.
>
> One thing: having the speaker section grounded and suppose we wind it
> outermost, then we have a built in shield, don't we? But that's no different
> either, is it?
>
> -j
> =========================================
> Jeremy Epstein........jepstein@ndbcap.com
> =========================================
>
=========================================================================
From: "Epstein, Jeremy" <JEpstein@ndbcap.com>
Subject: [JN] RE: backwards amp
Date: Wed, 17 Jan 2001 08:52:54 -0500
Source: Sound Digest Archive v02.n785
Thanks, Conrad. I guess Purl is right - we just have a wacky way to draw a
transformer coupled circuit - I don't really see where the benefit would be
in the negative supply at this point, do you?
- -j
=========================================
Jeremy Epstein........jepstein@ndbcap.com
=========================================
> -----Original Message-----
> From: Conrad Drake [mailto:conrad@directwest.iinet.net.au]
> Sent: Saturday, January 13, 2001 1:14 AM
> To: Epstein, Jeremy
> Cc: Joenet (E-mail)
> Subject: Re: backwards amp
>
>
>
>
> "Epstein, Jeremy" wrote:
> > Conrad says:
> > +__ spkr___+
> > ) |
> > ) |
> > +----------+--- *GND*
> > ) |
> > auto ) |
> > former ) |
> > | ----- DC
> > PLATE --- SUPPLY
>
> > >>>Which does take some extra wire:
> > >>If we've got 4k:4ohm step down that's sqrt(1000)
> > >> turns or about 30:1 So the "overhead" of getting
> > >> the DC out of the spkr is about 3%.<<<<
> >
> > I'm not sure what this part means. Are you talking about
> the difference in
> > ratio between having the secondary contained between the
> ends of the total
> > winding vs. having it hang off of one end? Trying to keep up here.
>
> Correct:
> the 30:1 autotransformer needs 29 x N turns of thin wire and one
> x N of thick.
> the "extended" autotransformer now needs 30 x N turns of thin.
>
> Interestingly, in theory, (from the viewpoint of fixed, if
> relative, DCR) the one x N of thick wire "needs" the same cross
> sectional area as the 30 x N turns of thin wire.
>
> The impression that I get is that, relatively speaking, the HT
> winding is over-provisioned: that is the ratio of gauges used
> does not match the turns ratio.
>
> Eg: our 30:1 transformer might use 60ga for the HT, and 2 ga for
> the LT. Both of which are outside the "normal" range one sees.
>
> Can anyone who actually winds transformers comment on whether
> this reflects (commercial) reality? Or point out the massive
> hole in my (zero reference to the manual) theory?
>
> > Would this output arrangement invert phase?
> Yes.
>
> > >>>>But, the real question is: if we have to wire
> > >>>>the "speaker" part of the "auto"former with a
> > >>>>separate gauge to the "plate" part, how is
> > >>>>this different to a conventional transformer?<<<
> >
> > Well, you would not need an insulation (dielectric) rated
> for the difference
> > between the plate voltage and ground, just the AC swing of
> the output is
> > all, I guess. And I'm assuming that the coupling between
> two pieces of one
> > winding will be closer than between two seperate windings,
> but as I think
> > about your challenging question I find I have no basis for
> that assumption.
>
> It's funny - but my knee jerk reaction would be to wind the
> speaker coil first (innermost) and then the HT around the
> outside.
>
> I'm afraid I'm not very good at visualising nearfield magnetic
> coupling: I'm used to dealing with either far field or capactive
> coupling.
>
> Yours,
> Conrad Drake
>
=========================================================================
From: dslagle@earthlink.net (dave slagle)
Subject: backwards amp... wuz [JN] What power supply
Date: Tue, 9 Jan 2001 11:31:25 -0500
Source: Sound Digest Archive v02.n779
oops... suppose i should have retitled this..
>Dave, you mention autoformer coupling, presumably for conventional speaker
>and dc offset issues, but assuming the current is accurately balanced
>between each half, then you've got no dc if you're output taps are
>symmetrical about CT? Of course, if one tube goes kaputt, then you may have
>a problem, then again, maybe not too much to worry about depending on the
>resistance of the "secondary".
i was referring to SE usage... i should have made that clear
reposted under new header
for the longest time i have been wanting to build a
backwards amp... i have the design, just haven't come up with all the iron
and figured out all the rubs yet
using the idea that the worst place for a transformer is on the output of
an amp, why not flip the whole thing around. all the transformer does is
impedance match and isolate, we could use an autoformer and ground the
output and use negative supplies, hell you could even direct couple all the
way back and using negative supplies... then your only problem becomes
isolating the grid of your input tube a cap or a trannie would do nicely
here... given the choice would you rather have your means of isolation deal
with 1V or 300V?
if you look at the whle picture here... you esentially built the entire amp
backwards.
the only problem i run into with the above idea is if the autoformer is a
tapped plate choke carrying DC... the speaker coil will not like the DC...
so some isolation is still needed... its always something.
dave (again)
=========================================================================
From: "Dave Slagle" <dslagle@earthlink.net>
Subject: Re: backwards amp... wuz [JN] What power supply
Date: Tue, 09 Jan 2001 21:28:33 -0500
Source: Sound Digest Archive v02.n779
> This discussion goes completely over my head.
> I don't get the circuit description.
> What are you saying Dave?
take a three stage all dc gain structure with a grid choke on the input and
a transformer on the output with positive supplies on the plates across the
board.
reverse i all... move the grid choke to the output and tap it for your
impedance match and ground it... stack negative supplies in the cathodes of
each previous stage, and then you need an input trannie on the first stage
to block
dc... hell take it back two stages dc (direct coupled) and IT couple your
first stage and you are back at ground potential.
the problems are
dc will flow through the speaker coil (makes me think field coil speaker?)
i have yet to wind an tapped choke for impedance matching that impresses me
that will carry dc... (don't even mention caps here)
its basically a good idea that won't work as i see it, but there may be a
creative way around it... so i figure i would toss it out there...
dave
=========================================================================
From: "Sellek, Grant (TSA)" <Grant.Sellek@transport.sa.gov.au>
Subject: RE: backwards amp... wuz [JN] What power supply
Date: Wed, 10 Jan 2001 10:51:48 +1030
Source: Sound Digest Archive v02.n779
This discussion goes completely over my head.
I don't get the circuit description.
What are you saying Dave?
Grant Sellek, Adelaide, Australia
>-----Original Message-----
>From: dslagle@earthlink.net [mailto:dslagle@earthlink.net]
>Sent: Wednesday, 10 January 2001 3:01 AM
>To: sound@deliverator.io.com
>Subject: backwards amp... wuz [JN] What power supply
>
>
>oops... suppose i should have retitled this..
>
>>Dave, you mention autoformer coupling, presumably for
>conventional speaker
>>and dc offset issues, but assuming the current is accurately balanced
>>between each half, then you've got no dc if you're output taps are
>>symmetrical about CT? Of course, if one tube goes kaputt,
>then you may have
>>a problem, then again, maybe not too much to worry about
>depending on the
>>resistance of the "secondary".
>
>i was referring to SE usage... i should have made that clear
>
>reposted under new header
>
>for the longest time i have been wanting to build a
>backwards amp... i have the design, just haven't come up with
>all the iron
>and figured out all the rubs yet
>
>using the idea that the worst place for a transformer is on
>the output of
>an amp, why not flip the whole thing around. all the
>transformer does is
>impedance match and isolate, we could use an autoformer and ground the
>output and use negative supplies, hell you could even direct
>couple all the
>way back and using negative supplies... then your only problem becomes
>isolating the grid of your input tube a cap or a trannie would
>do nicely
>here... given the choice would you rather have your means of
>isolation deal
>with 1V or 300V?
>
>if you look at the whle picture here... you esentially built
>the entire amp
>backwards.
>
>the only problem i run into with the above idea is if the
>autoformer is a
>tapped plate choke carrying DC... the speaker coil will not
>like the DC...
>so some isolation is still needed... its always something.
>
>dave (again)
>
>
>
=========================================================================
From: "Danielak, Robert M" <robert.m.danielak@lmco.com>
Subject: RE: backwards amp... wuz [JN] What power supply
Date: Wed, 10 Jan 2001 11:18:33 -0500
Source: Sound Digest Archive v02.n780
a picture's worth a thousand words.
let me see if i got you right.
> take a three stage all dc gain structure with a grid choke on the input and
> a transformer on the output with positive supplies on the plates across the
> board.
>
>
> reverse i all...
>
LOL
> move the grid choke to the output and tap it for your
> impedance match and ground it... stack negative supplies in the cathodes of
> each previous stage, and then you need an input trannie on the first stage
> to block
> dc...
>
oooooooh. *negative* supplies. how do you make those?!?
doncha need them reverse rectifiers or sumthin' ? ;)
actually, it's just a matter of where you put the *ground*
see below:
+----------+--- *GND*
| |
)__ spkr |
auto ) |
former ) |
) |
| ----- DC
PLATE --- SUPPLY
+--GRID | #3
| CATH |
| | |
| +----------+
| |
| +----------+
| | |
| ) |
| ) |
| ) |
| ) |
+----| ----- DC
PLATE --- SUPPLY
+--GRID | #2
| CATH |
| | |
| +----------+
| |
| +----------+
| | |
| ) |
| ) |
| ) |
| ) |
+----| ----- DC
PLATE --- SUPPLY
INo-+ +-GRID | #1
| | CATH |
)|( | |
IT )|( --- bias |
)|( - batt |
| | | |
| +---+----------+
|
GND
> hell take it back two stages dc (direct coupled) and IT couple your
> first stage and you are back at ground potential.
>
>
there's an interesting topology.
i'd call it "full-circle".
since your positive reference for the output stage is GND
and your negative reference for input stage is GND.
sorta blows the grid/plate bias for the 2nd stage, though.
hmmm... how would we do it?
+----------+--- *GND*
| |
)__ spkr |
auto ) |
former ) |
) |
| ----- DC
PLATE --- SUPPLY
+--GRID | #3
| CATH |
| | |
| +----------+ Note *negative* wrt GND
| |
| +----------+
| | |
| ) |
| ) |
| ) |
| ) |
+----| ----- DC
PLATE --- SUPPLY
+---GRID | #2
| CATH |
| | |
| +--+-----------+ Note *negative* wrt GND
| |
|--- bias
| -
| | +----------+ Note *positive* wrt GND
| | | |
| )||( |
| )||( |
| )||( |
|__)||( |
| ----- DC
PLATE --- SUPPLY
INo---+-GRID | #1
| CATH |
( | |
( --- bias |
( - batt |
| | |
+---+----------+
|
GND
if i drew this out on paper, i could do it in a circle,
and have the bottom connect to the top....
cool!
> the problems are
>
> dc will flow through the speaker coil
>
right.
big problem, i think.
fwiw, the DC voltage drop across the choke should not be very high, though. and even less at the out
put tap point.
> (makes me think field coil speaker?)
>
as far as i know, field coil speaker use a separate dc source
to excite the field magnet.
the voice coil gets the ac.
i'd imagine that any audio modulation on the field would show
up in the speaker output.
but i don't know what the sensitivity would be thru the field
winding.
i use some old field-coil speakers in guitar amps that i built.
the field coil is used as a filter choke in the power supply.
i'd imagine that there is a fair amount of ripple current
thru the field, yet i don't hear it.
that's why i doubt the field sensitivity is very high...
> i have yet to wind an tapped choke for impedance matching that impresses me
> that will carry dc...
>
hmmm...
> (don't even mention caps here)
>
ok. i'll do it a little bit further down the page... ;)
> its basically a good idea that won't work as i see it, but there may be a
> creative way around it... so i figure i would toss it out there...
>
i assume you feel it's a good idea because you avoid the
primary-secondary coupling, and the compromises involved with
leakage inductances/capacitances, etc.
i still wonder why the parafeeder haven't latched onto this approach.
with parafeed you get rid of dc, so why would you bother to provide
galvanic isolation to the secondary.
an autoformer would do just as well, if not better.
who knows, it might make a parafeeder out of you, dave...
it's a big compromise, but you're probably the only one set up to
build an autoformer output.
what are you trading. a "selectable" capacitor for the parasitics
that you are "stuck-with" in the OPT...
gotta get back to work, now...
bob.d.
=========================================================================
From: "Spence Barton" <ence-ack@rio.com>
Subject: Re: backwards amp... wuz [JN] What power supply
Date: Wed, 10 Jan 2001 12:48:46 -0800
Source: Sound Digest Archive v02.n780
>>
>> i use some old field-coil speakers in guitar amps that i built.
>> the field coil is used as a filter choke in the power supply.
>>
>> i'd imagine that there is a fair amount of ripple current
>> thru the field, yet i don't hear it.
>>
>> that's why i doubt the field sensitivity is very high...
Heres my theory...
When there is ripple on the supply to the field coil it is not heard at all
in the absence of signal because the voice coil has no current through it
save what is induced by the field coil and so is not magnetized and feels no
force from the ripple in the field. When there is a signal though voice
coil, the ripple does affect cone movement and is heard because it now has a
magnetized voice coil to work on. So not only is there hum but it amplitude
modulates the audio signal. Ick. ( Could be worse, I guess, if it were FM.)
Therefore, I think you have to have a very pure field current supply. This
is a somewhat pesky problem - because there is no audible hum with no signal
one might think everything was totally fine. I would guess if you had a
ripple equal to 2% of the DC voltage on the field coil it would be same as
having a ripple component equal to 2% of the signal to the voice coil in
terms of sensitivity but in the latter case you don't get the AM so it
probably would be easier to listen to. Plus it would be there all the time
and therefore be easier for the brain to ignore than the ripple plus a bunch
of side bands that come and go with the signal envelope.
Some of this comes from an e-mail exchange with the awesome Finn Hammer who
built the giant field coil woofer - field coil, voice coil, cone and wooden
frame all in his home shop. No longer on the list. At the time he said he
was being distracted from audio by the deep inner need to build big Tesla
coils.
spence
=========================================================================
From: "Paul Croft" <pcroft@iximd.com>
Subject: RE: backwards amp... wuz [JN] What power supply
Date: Wed, 10 Jan 2001 13:22:10 -0500
Source: Sound Digest Archive v02.n780
OHhhhh, Bob,
When you talk like this, the earth moves for us!!!!
Cheers,
Paul
> -----Original Message-----
> From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
> Behalf Of Danielak, Robert M
> Sent: Wednesday, January 10, 2001 11:19 AM
> To: 'sound@deliverator.io.com'
> Subject: RE: backwards amp... wuz [JN] What power supply
>
>
> a picture's worth a thousand words.
> let me see if i got you right.
>
> > take a three stage all dc gain structure with a grid choke on
> the input and
> > a transformer on the output with positive supplies on the
> plates across the
> > board.
> >
> >
> > reverse i all...
> >
> LOL
>
> > move the grid choke to the output and tap it for your
> > impedance match and ground it... stack negative supplies in the
> cathodes of
> > each previous stage, and then you need an input trannie on the
> first stage
> > to block
> > dc...
> >
> oooooooh. *negative* supplies. how do you make those?!?
> doncha need them reverse rectifiers or sumthin' ? ;)
>
> actually, it's just a matter of where you put the *ground*
>
> see below:
>
>
>
> +----------+--- *GND*
> | |
> )__ spkr |
> auto ) |
> former ) |
> ) |
> | ----- DC
> PLATE --- SUPPLY
> +--GRID | #3
> | CATH |
> | | |
> | +----------+
> | |
> | +----------+
> | | |
> | ) |
> | ) |
> | ) |
> | ) |
> +----| ----- DC
> PLATE --- SUPPLY
> +--GRID | #2
> | CATH |
> | | |
> | +----------+
> | |
> | +----------+
> | | |
> | ) |
> | ) |
> | ) |
> | ) |
> +----| ----- DC
> PLATE --- SUPPLY
> INo-+ +-GRID | #1
> | | CATH |
> )|( | |
> IT )|( --- bias |
> )|( - batt |
> | | | |
> | +---+----------+
> |
> GND
>
>
> > hell take it back two stages dc (direct coupled) and IT couple your
> > first stage and you are back at ground potential.
> >
> >
> there's an interesting topology.
> i'd call it "full-circle".
> since your positive reference for the output stage is GND
> and your negative reference for input stage is GND.
>
> sorta blows the grid/plate bias for the 2nd stage, though.
>
> hmmm... how would we do it?
>
> +----------+--- *GND*
> | |
> )__ spkr |
> auto ) |
> former ) |
> ) |
> | ----- DC
> PLATE --- SUPPLY
> +--GRID | #3
> | CATH |
> | | |
> | +----------+ Note *negative* wrt GND
> | |
> | +----------+
> | | |
> | ) |
> | ) |
> | ) |
> | ) |
> +----| ----- DC
> PLATE --- SUPPLY
> +---GRID | #2
> | CATH |
> | | |
> | +--+-----------+ Note *negative* wrt GND
> | |
> |--- bias
> | -
> | | +----------+ Note *positive* wrt GND
> | | | |
> | )||( |
> | )||( |
> | )||( |
> |__)||( |
> | ----- DC
> PLATE --- SUPPLY
> INo---+-GRID | #1
> | CATH |
> ( | |
> ( --- bias |
> ( - batt |
> | | |
> +---+----------+
> |
> GND
>
>
> if i drew this out on paper, i could do it in a circle,
> and have the bottom connect to the top....
>
> cool!
>
> > the problems are
> >
> > dc will flow through the speaker coil
> >
> right.
>
> big problem, i think.
>
> fwiw, the DC voltage drop across the choke should not be very
> high, though. and even less at the output tap point.
>
> > (makes me think field coil speaker?)
> >
> as far as i know, field coil speaker use a separate dc source
> to excite the field magnet.
>
> the voice coil gets the ac.
>
> i'd imagine that any audio modulation on the field would show
> up in the speaker output.
>
> but i don't know what the sensitivity would be thru the field
> winding.
>
> i use some old field-coil speakers in guitar amps that i built.
> the field coil is used as a filter choke in the power supply.
>
> i'd imagine that there is a fair amount of ripple current
> thru the field, yet i don't hear it.
>
> that's why i doubt the field sensitivity is very high...
>
> > i have yet to wind an tapped choke for impedance matching that
> impresses me
> > that will carry dc...
> >
> hmmm...
>
> > (don't even mention caps here)
> >
> ok. i'll do it a little bit further down the page... ;)
>
> > its basically a good idea that won't work as i see it, but
> there may be a
> > creative way around it... so i figure i would toss it out there...
> >
> i assume you feel it's a good idea because you avoid the
> primary-secondary coupling, and the compromises involved with
> leakage inductances/capacitances, etc.
>
> i still wonder why the parafeeder haven't latched onto this approach.
>
> with parafeed you get rid of dc, so why would you bother to provide
> galvanic isolation to the secondary.
>
> an autoformer would do just as well, if not better.
>
> who knows, it might make a parafeeder out of you, dave...
>
> it's a big compromise, but you're probably the only one set up to
> build an autoformer output.
>
> what are you trading. a "selectable" capacitor for the parasitics
> that you are "stuck-with" in the OPT...
>
> gotta get back to work, now...
>
> bob.d.
>
>
>
>
=========================================================================
From: Dan Marshall <mdaniel7@uswest.net>
Subject: Re: backwards amp... wuz [JN] What power supply
Date: Wed, 10 Jan 2001 14:55:24 +0000
Source: Sound Digest Archive v02.n780
Hi All,
Spence Barton wrote:
>
> >>
> >> i use some old field-coil speakers in guitar amps that i built.
> >> the field coil is used as a filter choke in the power supply.
> >>
> >> i'd imagine that there is a fair amount of ripple current
> >> thru the field, yet i don't hear it.
> >>
> >> that's why i doubt the field sensitivity is very high...
>
> Heres my theory...
>
> When there is ripple on the supply to the field coil it is not heard at all
> in the absence of signal because the voice coil has no current through it
> save what is induced by the field coil and so is not magnetized and feels no
> force from the ripple in the field.
Not so. Audible hum is not a function of whether the VC has current
through it. It is a direct relationship between the field-induced hum
voltage vs the VC circuit resistance, including the amp output Z. If
ripple current exists in the field coil, it will induce a voltage into
the VC by transformer action. When the VC is connected to an amp, which
is roughly equivalent to shorting the VC terminals (or if the terminals
are shorted together), the induced voltage will result in a hum current
flowing through the voice coil, which will be translated to cone
movement, or audible hum.
> When there is a signal though voice
> coil, the ripple does affect cone movement and is heard because it now has a
> magnetized voice coil to work on. So not only is there hum but it amplitude
> modulates the audio signal. Ick. ( Could be worse, I guess, if it were FM.)
The induced hum would be the same (to a first-order approximation)
whether a VC signal is present or not, assuming the hum component in the
field is constant vs signal level. The important factor being that the
ripple component in the field current will induce a voltage into the
voice coil, which will cause a VC current as a result of the near short
circuit presented by the amplifier output. As above, this is a function
of the field-induced VC voltage and the total VC circuit resistance.
Also of importance, the field, being an inductor, will tend to result in
a relatively constant current, even in the presence of some ripple
voltage from the first filter cap. At least the hum current is very
considerably less than the ripple voltage across the field. This in
itself will tend to minimize the field-induced hum.
Many speaker, such as the Jensen A-12, have hum-bucking coils built into
the field structure. This is a small coil which is connected in series
with the VC. With the proper number of turns, an equivalent value of
hum voltage will be induced into the hum-bucking coil as into the VC.
Properly phased and connected in series with the VC, this voltage will
effectively cancel (or buck) the hum induced into the VC by ripple
current in the field. The A-12 also has a rather heavy copper shorted
turn built into the pole piece which acts to short the ripple magnetism
from the field, as well as to negate the demagnetizing effects from the
VC current. BTW, these old speakers are quite amazing.
> Therefore, I think you have to have a very pure field current supply. This
> is a somewhat pesky problem - because there is no audible hum with no signal
> one might think everything was totally fine. I would guess if you had a
> ripple equal to 2% of the DC voltage on the field coil it would be same as
> having a ripple component equal to 2% of the signal to the voice coil in
> terms of sensitivity but in the latter case you don't get the AM so it
> probably would be easier to listen to. Plus it would be there all the time
> and therefore be easier for the brain to ignore than the ripple plus a bunch
> of side bands that come and go with the signal envelope.
From above, I would tend to think that either you have hum, or you
don't, irrespective of the signal level. Also, if you have 2% ripple
voltage across the field coil, the ripple current would be much less, as
the field coil is an inductor, which, as we know, attempts to keep
current constant. Of course, if the PS ripple voltage increases at high
level signals, then you have a somewhat different situation. This is
assuming no hum-bucking coil is provided. If one is provided, then the
ripple cancellation of the HB coil would tend to track these increases.
If B+ current increases at high signal levels, as with, say, an AB2
amplifier, this may cause some modulation, perhaps acting somewhat as a
volume expander on loud passages, assuming the time constants don't
cause too much delay. If the field is sufficiently strong to saturate
the front plate, then these effects would be minimized. With high power
(AB2) amplifiers it would be better to provide a separate field supply.
Also, I would think that a series field/filter coil would be inviting
problems with a SE amp, esp at very low frequencies where ripple values
reflected from the load are of a greater magnitude than the rectified
line ripple.
Dan Marshall
> Some of this comes from an e-mail exchange with the awesome Finn Hammer who
> built the giant field coil woofer - field coil, voice coil, cone and wooden
> frame all in his home shop. No longer on the list. At the time he said he
> was being distracted from audio by the deep inner need to build big Tesla
> coils.
>
> spence
=========================================================================
From: "Henry Platt" <hnplatt@massed.net>
Subject: Re: backwards amp... wuz [JN] What power supply
Date: Wed, 10 Jan 2001 19:22:59 -0400
Source: Sound Digest Archive v02.n781
Try using the field coil as a plate choke ;-)
- ----------
>From: Dan Marshall <mdaniel7@uswest.net>
>To: Spence Barton <ence-ack@rio.com>
>Cc: Joenet <sound@lists.io.com>
>Subject: Re: backwards amp... wuz [JN] What power supply
>Date: Wed, Jan 10, 2001, 10:55 AM
>
> Hi All,
>
> Spence Barton wrote:
>>
>> >>
>> >> i use some old field-coil speakers in guitar amps that i built.
>> >> the field coil is used as a filter choke in the power supply.
>> >>
>> >> i'd imagine that there is a fair amount of ripple current
>> >> thru the field, yet i don't hear it.
>> >>
>> >> that's why i doubt the field sensitivity is very high...
>>
>> Heres my theory...
>>
>> When there is ripple on the supply to the field coil it is not heard at all
>> in the absence of signal because the voice coil has no current through it
>> save what is induced by the field coil and so is not magnetized and feels no
>> force from the ripple in the field.
>
> Not so. Audible hum is not a function of whether the VC has current
> through it. It is a direct relationship between the field-induced hum
> voltage vs the VC circuit resistance, including the amp output Z. If
> ripple current exists in the field coil, it will induce a voltage into
> the VC by transformer action. When the VC is connected to an amp, which
> is roughly equivalent to shorting the VC terminals (or if the terminals
> are shorted together), the induced voltage will result in a hum current
> flowing through the voice coil, which will be translated to cone
> movement, or audible hum.
>
>> When there is a signal though voice
>> coil, the ripple does affect cone movement and is heard because it now has a
>> magnetized voice coil to work on. So not only is there hum but it amplitude
>> modulates the audio signal. Ick. ( Could be worse, I guess, if it were FM.)
>
> The induced hum would be the same (to a first-order approximation)
> whether a VC signal is present or not, assuming the hum component in the
> field is constant vs signal level. The important factor being that the
> ripple component in the field current will induce a voltage into the
> voice coil, which will cause a VC current as a result of the near short
> circuit presented by the amplifier output. As above, this is a function
> of the field-induced VC voltage and the total VC circuit resistance.
>
> Also of importance, the field, being an inductor, will tend to result in
> a relatively constant current, even in the presence of some ripple
> voltage from the first filter cap. At least the hum current is very
> considerably less than the ripple voltage across the field. This in
> itself will tend to minimize the field-induced hum.
>
=========================================================================
From: "Ellen Oler" <ellenoler@earthlink.net>
Subject: RE: backwards amp... wuz [JN] What power supply
Date: Wed, 10 Jan 2001 20:45:05 -0500
Source: Sound Digest Archive v02.n781
Excerpting just the auto former output section:
hmmm... how would we do it?
+----------+--- *GND*
| |
)__ spkr |
auto ) |
former ) |
) |
| ----- DC
PLATE --- SUPPLY
+--GRID | #3
| CATH |
| | |
| +----------+ Note *negative* wrt GND
| |
and focusing on the autoformer and speaker current loop:
+------+---GND-------)|
| )|K
)____________________)|
)
)
)
Then:
The DC current flowing through the speaker coil will relate ONLY to the
ratio of the DC resistances in the speaker coil and the DC resistance in
TOPMOST SECTION ONLY of the autoformer.
As long as the DCR of this TOP SECTION is reduced to be negligible compared
to the voice coil DCR, MOST of the current (equal to the total current
flowing through the output tube) will be flowing through the autoformer
portion of this loop.
Implies fine wire in the voice coil and honkin' fat wire in the TOP SECTION
ONLY of the autoformer.
Intuitively, we can easily see this: as long as there is negligible DCR
between the top of the autoformer and the tap then there will be a
negligible DC drop and negligible DC current through the voice coil.
Since there is a step-down in this auto former, only a relatively small
section at the "top" needs to be wound this way (phat), I think. 1/18th of
the total for a 2K5:8 tranny.
- -j
=========================================================================
From: dslagle@earthlink.net (dave slagle)
Subject: RE: backwards amp... wuz [JN] What power supply
Date: Thu, 11 Jan 2001 07:51:41 -0500
Source: Sound Digest Archive v02.n781
j...
60 ma through the tube...
16 ohm voice coil
.25 ohm secondary (thats low!... maybe a foil secondary???)
you still get 1ma of current through the speaker coil
i suspect that this wont do much damage even to a lowther coil, but it will
offset the driver from its normal position, i suspect depending on the
surround adding non-linearity to the cone excursion??? or maybe given that
its non-linear as it is, it could help things out? that whole air is
easier to expand than it is to compress (or is it the other way around.)
still worth some thought... speaker guru's?
i also love the idea of a f/c plate choke... definately out of the box thinking
dave
=========================================================================
From: Conrad Drake <conrad@directwest.iinet.net.au>
Subject: RE: backwards amp... wuz [JN] What power supply
Date: Fri, 12 Jan 2001 07:00:55 +0800
Source: Sound Digest Archive v02.n782
> hmmm... how would we do it?
>
> +----------+--- *GND*
> | |
> )__ spkr |
> auto ) |
> former ) |
> ) |
> | ----- DC
> PLATE --- SUPPLY
> +--GRID | #3
> | CATH |
> | | |
> | +----------+ Note *negative* wrt GND
> | |
>
What is the Vdc(speaker)?
DC current: 100mA, DCR 1K -> total DC voltage 100V. Speaker
winding will be at least 10x thicker -> 1/10th resistance. So
DCR(speaker) = 1K x 1/30 x 1/10 => 0.33V
I cannot believe that someone hasn't suggested it yet, but why
not
+__ spkr___+
) |
) |
+----------+--- *GND*
) |
auto ) |
former ) |
| ----- DC
PLATE --- SUPPLY
+--GRID | #3
| CATH |
| | |
| +----------+ Note *negative* wrt GND
| |
Which does take some extra wire:
If we've got 4k:4ohm step down that's sqrt(1000) turns or about
30:1
So the "overhead" of getting the DC out of the spkr is about 3%.
But, the real question is: if we have to wire the "speaker" part
of the "auto"former with a separate guage to the "plate" part,
how is this different to a conventional transformer?
Yours,
Conrad Drake
- --
Direct West Invs. P/L Solutions for Embedded Systems.
conrad@directwest.ii.net (ph)+61 40 747 1611
http://directwest.ii.net (fx)+61 8 9285 1011
12 Gayton Road, City Beach, WA 6015 AUSTRALIA
=========================================================================
From: Martin Seddon <mseddon@iinet.net.au>
Subject: RE: backwards amp... wuz [JN] What power supply
Date: Sun, 14 Jan 2001 00:04:24 +0800
Source: Sound Digest Archive v02.n783
Conrad wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>
I cannot believe that someone hasn't suggested it yet, but why
not
+__ spkr___+
) |
) |
+----------+--- *GND*
) |
auto ) |
former ) |
| ----- DC
PLATE --- SUPPLY
+--GRID | #3
| CATH |
| | |
| +----------+ Note *negative* wrt GND
| |
Which does take some extra wire:
If we've got 4k:4ohm step down that's sqrt(1000) turns or about
30:1
So the "overhead" of getting the DC out of the spkr is about 3%.
But, the real question is: if we have to wire the "speaker" part
of the "auto"former with a separate guage to the "plate" part,
how is this different to a conventional transformer?
<<<<<<<<<<<<<<<<<<<<<<<<<
Very neat - thanks Conrad. Auto former to 'normal' transformer in one
move. I guess a conventionally wired autoformer step down winding would
have to be heavier gauge for power balance.
But who need the amp backwards? - be like me - run your speakers at B+ ;-)
Martin
=========================================================================
From: dslagle@earthlink.net (dave slagle)
Subject: [JN] bad caps... bad bad caps....
Date: Thu, 25 Feb 1999 10:43:43 -0500
Source: Sound Digest Archive v02.n061
hey the ulbrich trannies showed up yesterday, and quickly were clipped into
system... and whaddya know more of those nasty nasty defib caps reared
their ugly sound... went back the the trannies that were in there and the
defib sound was gone...
I was crushed again...back in went the ulbrich's and moved on... so I did
a little balancing act and pulled out the first defibs on the 45 for an
elna... hmmm we are getting somewhere... next the second defibs were
replaced with a solen... yuck there was the solen sound I have grown to
dislike... so in went some big 'ol oils... ahhh now we are getting
somewhere...still not balanced, but getting there
I have to say that I have never heard such differences before... it hurts
my head... the amount the sound can change with swapping one pair of
caps...this has never happened to me before...
I honestly don't know what to make of it... I guess I could consider
myself lucky since there will be no hair-splitting deciding if there was a
change... just deciding which cap combo i prefer...
strange!
dave
=========================================================================
From: Steve Van Osdell <svanos@queencity.com>
Subject: [JN] Bad luck with my 2nd amp
Date: Fri, 18 Aug 2000 07:49:05 -0400
Source: Sound Digest Archive v02.n632
I finished my second amp last night and was ready to listen to some
stereo, but had a piece of bad luck. The potted military power
transformer was bad. Dead short in it (it appears) - blew the fuse as
the variac passed 30 volts.
I was wondering if some of you iron collectors out there might have one
like it before I got shopping for two new transformers (I'd have to
replace the other one too for looks).
Here are the number written on it....
Here is the number...Q-880-51 Transformer Tech TTI-5136
If anyone has an extra one they'd part with, please let me know asap,
and how much.
Thanks, Steve
=========================================================================
From: Patrick Currie <tubesguy@chorus.net>
Subject: Re: [JN] Bad luck with my 2nd amp
Date: Fri, 18 Aug 2000 08:18:16 -0500 (CDT)
Source: Sound Digest Archive v02.n632
>I finished my second amp last night and was ready to listen to some
>stereo, but had a piece of bad luck. The potted military power
>transformer was bad. Dead short in it (it appears) - blew the fuse as
>the variac passed 30 volts.
>
>I was wondering if some of you iron collectors out there might have one
>like it before I got shopping for two new transformers (I'd have to
>replace the other one too for looks).
>
>Here are the number written on it....
>Here is the number...Q-880-51 Transformer Tech TTI-5136
>
>If anyone has an extra one they'd part with, please let me know asap,
>and how much.
>
>Thanks, Steve
Steve -
What are the voltages? Maybe one of us has two of something else that
would work. - Pat
=========================================================================
From: "John Hancock" <John_Hancock@swissre.com>
Subject: [JN] bad physics and worse physics
Date: Wed, 14 Apr 1999 14:42:49 +0100
Source: Sound Digest Archive v02.n124
Christian Rintelen wrote:
>check this out -- but be warned, it's waaaay over the top....
>
snip...
>
>(To quote from the abstract: "The Vacuum Triode Amplifier (VTA)
>
snip...
That was hilarious. God bless them. I wonder if they have a recipe for
gold as well.
Well, I finally had a chance to check out the Joe list again after a
vacation and a busy period at work. Some people asked about my post
regarding the accelerating expansion of the universe. The question was how
could the universe be accelerating and my answer is I don't have a clue.
Back when I was working at Fermilab (13 years ago--I've since switched to
economics as a profession so now my knowledge is pretty much limited to
what I read in Scientific American and Astronomy magazine), there was a lot
of work being done that speculated that the expansion of the universe
accelerated in the early stages of history immediately following the big
bang. The acceleration would go along way in explaining a number of
stylized facts about the universe that are difficult to explain under the
current rules of physics. In particular, it would explain why the current
rate of expansion is so close to the critical rate at which the universe
will asymptotically stop expanding--rather than either expanding forever if
the current rate of expansion was just a little bit higher or else
collapsing back onto itself if the rate of expansion was just a little bit
slower. The acceleration would also explain why matter is distributed
throughout space so uniformly, rather than being clumped together. The
theories being thrown around at the time speculated that particles
exhibited a property called super symmetry--that is, at very high energies,
like after the big bang, all particles behave identically and so behave in
a manner similar to antigravity. Only after the particles cool do they
exhibit spin which differentiates the particles and leads to the strong and
weak forces, etc. These theories, though, only predicted an acceleration
in the very early history of the universe, so it was a bit of a surprise to
find that the universe may still be accelerating. One theory I have been
hearing about to explain this is that there is a vacuum energy--empty space
has mass. This mass impels space to expand. As space expands, there is
more of it, so the expansion accelerates. Now, why space having mass would
cause it to accelerate, I have no idea.
One other thing, if the discovery that the expansion is accelerating holds
up, Einstein would be right about his cosmological constant, but for the
wrong reason. Einstein came up with the constant to explain how the
universe could be static when gravity should cause it to collapse. Twenty
years later, Hubble discovered that the universe was in fact expanding.
Hope somebody finds this interesting and also hope that my litlle knowledge
of physics is not worse than no knowledge of physics, ie. VTA above.
John
=========================================================================
From: Jonathan Morrison <ppdiva@rcn.com>
Subject: Re: [JN] bad physics and worse physics
Date: Thu, 15 Apr 1999 12:06:38 -0400
Source: Sound Digest Archive v02.n125
At 05:07 PM 4/15/99 +0200, Adnan Arduman wrote:
>Don't you think this is a better example for this list? And also there is
>the fact that most of the Joes don't use combs (this is only a wild guess)
>:^)
>
>Adnan
Especially the ones that touch B+ ... JDM
=========================================================================
From: "John Hancock" <John_Hancock@swissre.com>
Subject: [JN] bad physics and worse physics
Date: Thu, 15 Apr 1999 13:22:34 +0100
Source: Sound Digest Archive v02.n125
Some more questions on physics:
Bart wrote:
>Is infinity purely an abstract mathematical concept which does not exist
in
>nature?
Nope, it exists, at least in terms of possibilites. Think about all the
ways you could comb your hair. Quantum theory works the same way.
>If not, then anything, no matter how low the probability, that can exist
/
>happen will exist / happen and be happenning somewhere as we speak.
>
>Somewhere Elvis will be marrying me to.....
>
>etc., etc.
>
>Whats the logic error?
This is a common misconception. You could comb your hair for all eternity,
but there are also an infinite number of ways to comb your hair, so your
hair will never be combed exactly the same way twice. The question here is
intuitively which infinity is bigger? Believe it or not, there are answers
to that question. Try algebraic topology or measure theory if you want to
know more.
>If the universe and time aren't infinite then how do you fall off the edge
>and to where / when?
The universe could be finite, but have no edge--just like a sphere is
finite, but has no edge. The universe could just fold back into itself.
This could only happen, though if there is a fourth dimension. The
implications of this are pretty cool. It would mean that what we think are
different galaxies in the sky are really the same galaxies viewed from
different angles at different times. There will be an interesting
experiment carried out once this new NASA satellite (I have forgotten the
name) goes into orbit. The satellite will be examining the low frequency
radiation left over from the big bang. If the universe is finite (and not
too large) then there should be circles of repeating patterns in the
radiation. If the circles repeat one time, then the universe is large
enough that light could travel the length of the universe twice during the
lifetime of the universe. If the circles repeat more than that, the
universe is smaller. If the circles don't repeat, then the universe is
larger.
>What was before time?
>
>Is there a DOG?
OK, now we've wondered into religion. I'll stay away from that one. Once
again--I ain't no expert. Even when I was a physicist, I worked in high
energy physics, not cosmology, so take my wisdoms with a grain of salt. I
am now an economist and economics is one of those subjects that everyone
feels they are an expert on even without knowing much about the topic. I
really get pissed off some times about the economic logic being profligated
by the likes of Ross Perot and just about every European politician and I'm
sure a real physicist would cringe at my pop-physics understandings of
these topics. But, it is fun to ponder...
John
=========================================================================
From: Adnan Arduman <adnana@turk.net>
Subject: Re: [JN] bad physics and worse physics
Date: Thu, 15 Apr 1999 17:07:55 +0200
Source: Sound Digest Archive v02.n125
>Nope, it exists, at least in terms of possibilites. Think about all the
>ways you could comb your hair. Quantum theory works the same way.
Or, think about the number of different amplifiers with different sonic
characters you can build out of a single schematic just by playing with
components and their combinations.
This is the beauty of our hobby.
Don't you think this is a better example for this list? And also there is
the fact that most of the Joes don't use combs (this is only a wild guess)
:^)
Adnan
visit my personal "NUANCE & FLUENCE" web site:
http://www.arduman.com/aa
tel: +90-216-310 44 70 (w)
fax: +90-216-343 42 01
e-mail: adnana@turk.net
=========================================================================
From: Zyxtan@aol.com
Subject: Re: [JN] bad physics and worse physics
Date: Thu, 15 Apr 1999 13:19:23 EDT
Source: Sound Digest Archive v02.n126
In a message dated 4/15/99 11:11:08 AM US Eastern Standard Time,
ppdiva@rcn.com writes:
> Especially the ones that touch B+ ... JDM
and B+ is connected to one of Tom Danley's "widow maker " 4,400uF capacitors.
paul(zyxtan@aol.com)
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: Re: [JN] bad physics and worse politics
Date: Thu, 15 Apr 1999 15:13:11 +0200
Source: Sound Digest Archive v02.n125
> De : John Hancock <John_Hancock@swissre.com>
> Date : jeudi 15 avril 1999 14:22
> OK, now we've wondered into religion. I'll stay away from that one.
<CUT>
> I
> really get pissed off some times about the economic logic being
profligated
> by the likes of Ross Perot and just about every European politician
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
And you should stay away also on that subject!
This is out of the subject here and I prefer to know what you think about a
tube amplifier or about a loudspeaker than "about every European
politician"...
Best regards from Europe!
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: "John Hancock" <John_Hancock@swissre.com>
Subject: Re: [JN] bad physics and worse politics
Date: Fri, 16 Apr 1999 09:16:31 +0100
Source: Sound Digest Archive v02.n126
Jean-Michel,
Please don't take what I wrote personally. I have an even lower opinion of
US politicians. I could spend equal time denigrating them if it would
please you. The only reason why I singled out European politicians is that
US politicians don't tend to have policies, instead they have "values." US
politicians, to a large extent, leave the policies to professional
economists and instead focus on uncovering scandals about one another.
It's a perverse system, but in the end it works out better than you might
think. Please understand, what I said was not a dig against Europe, I
quite like living here and I live here by choice--I wasn't transfered on
some expat contract, I found my own way here.
John
> OK, now we've wondered into religion. I'll stay away from that one.
<CUT>
> I
> really get pissed off some times about the economic logic being
profligated
> by the likes of Ross Perot and just about every European politician
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
And you should stay away also on that subject!
This is out of the subject here and I prefer to know what you think about a
tube amplifier or about a loudspeaker than "about every European
politician"...
Best regards from Europe!
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: "hopper chu" <achu@medcaminc.com>
Subject: RE: [JN] Bad power tranny?
Date: Wed, 6 Dec 2000 09:44:36 -0800
Source: Sound Digest Archive v02.n753
Hi Dave,
(1) have you try another 5U4?
(2) 470 uF strike me as being a bit much as the first filter (might be
taxing your choke and tyranny over the years).
regards
hopper
=========================================================================
From: Dan Marshall <mdaniel7@uswest.net>
Subject: Re: [JN] Bad power tranny?
Date: Wed, 06 Dec 2000 09:52:52 +0000
Source: Sound Digest Archive v02.n753
Hi Dave,
From the symptoms you described I don't see how it could be a PT fault
other than possibly of the 5 V winding being leaky to ground, causing
the B+ current to be too high. The plates glowing red is indicative of
excessive dc load current. Since you have eliminated the rectifier tube
and filter cap by substituting others, this leaves the choke as the most
likely suspect, or perhaps a bad rectifer tube socket.
Inspect the rectifier socket carefully for cracks, or burnt areas.
Occasionally they will arc over and make a low resistance path.
Assuming the socket is OK, the first test would be to remove the
rectifer tube, turn it on, and see whether it still blows fuses, or if
the PT overheats. If it blows the fuse, or overheats, the PT is likely
bad, though I doubt that it will, since the glowing plates indicates
excessive dc current. Assuming it doesn't blow the fuse, check the
transformer secondary voltages. If they are OK and the transformer
does not overheat or blow fuses, it is probably OK, except for the
possibly of an internal 5 V to ground leakage, which would cause the B+
current to be excessive. So check to see whether this may be the case.
If this is the case you might just add a second small 5 V filament
transformer, or perhaps go to SS rectifiers, though this would give you
a fair bit higher B+ voltage.
Next, check the choke for leakage to ground and check its dc resistance
to see if it has changed, assuming you know its original resistance.
If it has leakage to ground, you have found your problem. If it has
shorted turns, it will look essentially like a short, in which case the
B+ will be quite a bit higher than normal, perhaps exceeding the filter
caps rated voltage thus causing excessive leakage current. Check the B+
at initial turn-on, before it blows the fuse, and see whether the B+ is
excessive. If so perhaps the choke has shorted turns. Otherwise, a
short/gnd has occurred somewhere.
DM
Dave Stagner wrote:
>
> I need some help debugging a power supply... i suspect i have a blown
> power transformer, but i'd like some confirmation from my symptoms.
>
> The power xformer is a big UTC welded steel can thing that has been in use
> on this amp for ~3 years. The power supply circuit is a basic choke
> supply, 5U4 into a huge low-DCR choke, followed by a 470uf cap. Grounding
> is a 12ga copper buss wire from the input jacks to the HT center tap on
> the power xformer. The AC line follows standard safety procedures
> (three-prong cord, chassis grounded, surge suppressor). Fuses are 3A
> slow-blow. Overall, the supply makes about 310v, and has powered stereo
> PP 6B4Gs for years without ever getting hot or behaving at all strangely.
> Until now.
>
> When i turn it on, the rectifier tube gets VERY hot quickly - the plates
> glow cherry red. After a little while (no longer than 30 seconds), the
> fuse blows. This seems like a short, so i've systematically disconnected
> everything downstream or parallel (filament supplies, output xformers,
> additional filter stages). All that's left is HT to the rectifier tube,
> then the choke, the cap, and a 330k wirewound resistor from the cap to the
> ground buss. I've tried swapping rectifiers, caps, even wire. Careful
> checking with a VOM can't find any unexpected continuities in this
> simplified circuit. The cap has a charge and is draining normally across
> the bleed resistor after the fuse blows.
>
> So now i suspect the power transformer. Does it seem like i'm on the
> right track? Please tell me before i have to drill new holes in the
> chassis to accomodate a new xformer...
> --
> Dave Stagner <dstagner@talkware.net>
> Universal Talkware Corporation
> 10 Second St. NE Suite 400, Minneapolis MN 55413
> ph: 612-843-6749 fax: 612-843-6707
=========================================================================
From: Dave Stagner <dstagner@talkware.net>
Subject: [JN] Bad power tranny?
Date: Wed, 6 Dec 2000 10:22:24 -0600
Source: Sound Digest Archive v02.n753
I need some help debugging a power supply... i suspect i have a blown
power transformer, but i'd like some confirmation from my symptoms.
The power xformer is a big UTC welded steel can thing that has been in use
on this amp for ~3 years. The power supply circuit is a basic choke
supply, 5U4 into a huge low-DCR choke, followed by a 470uf cap. Grounding
is a 12ga copper buss wire from the input jacks to the HT center tap on
the power xformer. The AC line follows standard safety procedures
(three-prong cord, chassis grounded, surge suppressor). Fuses are 3A
slow-blow. Overall, the supply makes about 310v, and has powered stereo
PP 6B4Gs for years without ever getting hot or behaving at all strangely.
Until now.
When i turn it on, the rectifier tube gets VERY hot quickly - the plates
glow cherry red. After a little while (no longer than 30 seconds), the
fuse blows. This seems like a short, so i've systematically disconnected
everything downstream or parallel (filament supplies, output xformers,
additional filter stages). All that's left is HT to the rectifier tube,
then the choke, the cap, and a 330k wirewound resistor from the cap to the
ground buss. I've tried swapping rectifiers, caps, even wire. Careful
checking with a VOM can't find any unexpected continuities in this
simplified circuit. The cap has a charge and is draining normally across
the bleed resistor after the fuse blows.
So now i suspect the power transformer. Does it seem like i'm on the
right track? Please tell me before i have to drill new holes in the
chassis to accomodate a new xformer...
- --
Dave Stagner <dstagner@talkware.net>
Universal Talkware Corporation
10 Second St. NE Suite 400, Minneapolis MN 55413
ph: 612-843-6749 fax: 612-843-6707
=========================================================================
From: Dave Stagner <dstagner@talkware.net>
Subject: Re: [JN] Bad power tranny?
Date: Wed, 6 Dec 2000 11:17:41 -0600
Source: Sound Digest Archive v02.n753
On Wed, Dec 06, 2000 at 12:03:58PM -0500, Roscoe Primrose spake thusly:
> Dave Stagner wrote:
>
> >
> > When i turn it on, the rectifier tube gets VERY hot quickly - the plates
> > glow cherry red. After a little while (no longer than 30 seconds), the
> > fuse blows. This seems like a short, so i've systematically disconnected
> > everything downstream or parallel (filament supplies, output xformers,
> > additional filter stages). All that's left is HT to the rectifier tube,
> > then the choke, the cap, and a 330k wirewound resistor from the cap to the
> > ground buss. I've tried swapping rectifiers, caps, even wire. Careful
> > checking with a VOM can't find any unexpected continuities in this
> > simplified circuit. The cap has a charge and is draining normally across
> > the bleed resistor after the fuse blows.
>
> I'm guessing it's not the transformer if the rectifier is glowing red,
> sounds like too much current downstream of the rectifier. Possibly an
> insulation breakdown in the choke that you can't detect with the low
> voltage from your VOM. Can you hook your VOM up to measure the current
> output from the recitifier?
I'm not sure... the DCR on the choke seems okay (77 ohms), but of course
the VOM doesn't put hundreds of volts on it. And it's not grounded
anywhere, so at worst it would stop the choke action... the only load to
ground now is a 330k resistor, which shouldn't pass much current at 310v
(or the 450 or so volts if the choke is failing so it behaves like cap
input). On the other hand, if the choke is shorting to its housing, which
is bolted to the chassis, and only doing so under high voltage conditions,
that could explain it.
- --
Dave Stagner <dstagner@talkware.net>
Universal Talkware Corporation
10 Second St. NE Suite 400, Minneapolis MN 55413
ph: 612-843-6749 fax: 612-843-6707
=========================================================================
From: russ arbuthnot <russ3@southern.com>
Subject: Re: [JN] Bad power tranny?
Date: Wed, 6 Dec 2000 11:22:47 -0600
Source: Sound Digest Archive v02.n753
Dave, when i built my first amp, I accidentally had the center tap of the
5V filiment supply to my rectifier grounded. I had the cherry plates and
the blown fuses just like you mentioned until i figured it out.
Unfortunately, if your amp has been working for years in its current
configuration, I doubt this is the problem.
Russ
On Wed, 6 Dec 2000, Tim Reese wrote:
> Dave, following the usual disclaimer that I'm only a hack at this stuff,
> I'd first pull the rectifier and power up the transformer with no load.
> If the fuse blows, I'd say that's conclusive that you have a shorted
> transformer. With no load, I'd then measure the AC volts across the HT
> checking for symmetry with the center tap. I've seen this before - an
> internal short in one half of the HT winding makes the CT no longer at
> center. Also made the PT hot like a stove... and changes the B+ volts.
>
> Not sure how this fits with your red plate symptoms though. I'd be more
> suspect of a shorted choke or cap downstream in that case.
>
> hth tr
> ----------------------------------------------------------------------
> Visit http://www.nmr.MGH.harvard.edu/~reese MRI, tube audio, reptiles
> Tim Reese, MGH NMR Center reese@nmr.MGH.harvard.edu
>
> >I need some help debugging a power supply... i suspect i have a blown
> >power transformer, but i'd like some confirmation from my symptoms.
> >
> >The power xformer is a big UTC welded steel can thing that has been in use
> >on this amp for ~3 years. The power supply circuit is a basic choke
> >supply, 5U4 into a huge low-DCR choke, followed by a 470uf cap. Grounding
> >is a 12ga copper buss wire from the input jacks to the HT center tap on
> >the power xformer. The AC line follows standard safety procedures
> >(three-prong cord, chassis grounded, surge suppressor). Fuses are 3A
> >slow-blow. Overall, the supply makes about 310v, and has powered stereo
> >PP 6B4Gs for years without ever getting hot or behaving at all strangely.
> >Until now.
> >
> >When i turn it on, the rectifier tube gets VERY hot quickly - the plates
> >glow cherry red. After a little while (no longer than 30 seconds), the
> >fuse blows. This seems like a short, so i've systematically disconnected
> >everything downstream or parallel (filament supplies, output xformers,
> >additional filter stages). All that's left is HT to the rectifier tube,
> >then the choke, the cap, and a 330k wirewound resistor from the cap to the
> >ground buss. I've tried swapping rectifiers, caps, even wire. Careful
> >checking with a VOM can't find any unexpected continuities in this
> >simplified circuit. The cap has a charge and is draining normally across
> >the bleed resistor after the fuse blows.
> >
> >So now i suspect the power transformer. Does it seem like i'm on the
> >right track? Please tell me before i have to drill new holes in the
> >chassis to accomodate a new xformer...
> >--
> >Dave Stagner <dstagner@talkware.net>
> >Universal Talkware Corporation
> >10 Second St. NE Suite 400, Minneapolis MN 55413
> >ph: 612-843-6749 fax: 612-843-6707
> >
>
=========================================================================
From: Tim Reese <tgrmail@nmr.MGH.harvard.EDU>
Subject: Re: [JN] Bad power tranny?
Date: Wed, 6 Dec 2000 11:45:51 -0500 (EST)
Source: Sound Digest Archive v02.n753
Dave, following the usual disclaimer that I'm only a hack at this stuff,
I'd first pull the rectifier and power up the transformer with no load.
If the fuse blows, I'd say that's conclusive that you have a shorted
transformer. With no load, I'd then measure the AC volts across the HT
checking for symmetry with the center tap. I've seen this before - an
internal short in one half of the HT winding makes the CT no longer at
center. Also made the PT hot like a stove... and changes the B+ volts.
Not sure how this fits with your red plate symptoms though. I'd be more
suspect of a shorted choke or cap downstream in that case.
hth tr
- ----------------------------------------------------------------------
Visit http://www.nmr.MGH.harvard.edu/~reese MRI, tube audio, reptiles
Tim Reese, MGH NMR Center reese@nmr.MGH.harvard.edu
>I need some help debugging a power supply... i suspect i have a blown
>power transformer, but i'd like some confirmation from my symptoms.
>
>The power xformer is a big UTC welded steel can thing that has been in use
>on this amp for ~3 years. The power supply circuit is a basic choke
>supply, 5U4 into a huge low-DCR choke, followed by a 470uf cap. Grounding
>is a 12ga copper buss wire from the input jacks to the HT center tap on
>the power xformer. The AC line follows standard safety procedures
>(three-prong cord, chassis grounded, surge suppressor). Fuses are 3A
>slow-blow. Overall, the supply makes about 310v, and has powered stereo
>PP 6B4Gs for years without ever getting hot or behaving at all strangely.
>Until now.
>
>When i turn it on, the rectifier tube gets VERY hot quickly - the plates
>glow cherry red. After a little while (no longer than 30 seconds), the
>fuse blows. This seems like a short, so i've systematically disconnected
>everything downstream or parallel (filament supplies, output xformers,
>additional filter stages). All that's left is HT to the rectifier tube,
>then the choke, the cap, and a 330k wirewound resistor from the cap to the
>ground buss. I've tried swapping rectifiers, caps, even wire. Careful
>checking with a VOM can't find any unexpected continuities in this
>simplified circuit. The cap has a charge and is draining normally across
>the bleed resistor after the fuse blows.
>
>So now i suspect the power transformer. Does it seem like i'm on the
>right track? Please tell me before i have to drill new holes in the
>chassis to accomodate a new xformer...
>--
>Dave Stagner <dstagner@talkware.net>
>Universal Talkware Corporation
>10 Second St. NE Suite 400, Minneapolis MN 55413
>ph: 612-843-6749 fax: 612-843-6707
>
=========================================================================
From: Roscoe Primrose <roscoe@aiko.com>
Subject: Re: [JN] Bad power tranny?
Date: Wed, 06 Dec 2000 12:03:58 -0500
Source: Sound Digest Archive v02.n753
Dave Stagner wrote:
>
> When i turn it on, the rectifier tube gets VERY hot quickly - the plates
> glow cherry red. After a little while (no longer than 30 seconds), the
> fuse blows. This seems like a short, so i've systematically disconnected
> everything downstream or parallel (filament supplies, output xformers,
> additional filter stages). All that's left is HT to the rectifier tube,
> then the choke, the cap, and a 330k wirewound resistor from the cap to the
> ground buss. I've tried swapping rectifiers, caps, even wire. Careful
> checking with a VOM can't find any unexpected continuities in this
> simplified circuit. The cap has a charge and is draining normally across
> the bleed resistor after the fuse blows.
I'm guessing it's not the transformer if the rectifier is glowing red,
sounds like too much current downstream of the rectifier. Possibly an
insulation breakdown in the choke that you can't detect with the low
voltage from your VOM. Can you hook your VOM up to measure the current
output from the recitifier?
Peace
- --
Roscoe Primrose -- mailto:roscoe@aiko.com --
http://www.aiko.com/roscoe
"Once in a while you get shown the light
In the strangest of places if you look at it right." Robert Hunter
"640K ought to be enough for anybody" , Bill Gates, 1981
=========================================================================
From: "Danielak, Robert M" <robert.m.danielak@lmco.com>
Subject: RE: [JN] Bad power tranny?
Date: Wed, 06 Dec 2000 12:28:29 -0500
Source: Sound Digest Archive v02.n753
i'd have to second tim's approach.
pull the rectifier and measure the HV AC.
not sure how a short in the secondary would cause the rectifiers to glow red.
but perhaps a short in the primary (shorting out some # of turns).
this would cause the output voltage to rise and perhaps overdissipate the
rectifier....
perhaps also a short from the rectifier filament or filament winding to ground.
also trace out the associated wiring for possible shorts.
you could also check the cap.
put an ohmmeter across and see if it continues to climb in impedance...
i should also mention that the 5u4 probably does not like the turn-on surge that it gets
with a 470uF cap (given the low DCR choke).
also, 240mA + is also very near the rating of a single 5u4
and what is the voltage rating of the cap?
the turn-on surge must be over 450V (since the 330k bleeder is not enough
to wet the choke).
these last few comments are simple general guidelines, that i'm sure you are aware of.
5u4's are rugged and cheap, and it's worked til now.
but they might be contributing factors.
but usually i find a wiring or component lead short somewhere..
bob.d.
> ----------
> From: Tim Reese[SMTP:tgrmail@nmr.MGH.harvard.EDU]
> Sent: Wednesday, December 06, 2000 11:45 AM
> To: dstagner@talkware.net
> Cc: sound@lists.io.com
> Subject: Re: [JN] Bad power tranny?
>
> Dave, following the usual disclaimer that I'm only a hack at this stuff,
> I'd first pull the rectifier and power up the transformer with no load.
> If the fuse blows, I'd say that's conclusive that you have a shorted
> transformer. With no load, I'd then measure the AC volts across the HT
> checking for symmetry with the center tap. I've seen this before - an
> internal short in one half of the HT winding makes the CT no longer at
> center. Also made the PT hot like a stove... and changes the B+ volts.
>
> Not sure how this fits with your red plate symptoms though. I'd be more
> suspect of a shorted choke or cap downstream in that case.
>
> hth tr
> ----------------------------------------------------------------------
> Visit http://www.nmr.MGH.harvard.edu/~reese MRI, tube audio, reptiles
> Tim Reese, MGH NMR Center reese@nmr.MGH.harvard.edu
>
> >I need some help debugging a power supply... i suspect i have a blown
> >power transformer, but i'd like some confirmation from my symptoms.
> >
> >The power xformer is a big UTC welded steel can thing that has been in use
> >on this amp for ~3 years. The power supply circuit is a basic choke
> >supply, 5U4 into a huge low-DCR choke, followed by a 470uf cap. Grounding
> >is a 12ga copper buss wire from the input jacks to the HT center tap on
> >the power xformer. The AC line follows standard safety procedures
> >(three-prong cord, chassis grounded, surge suppressor). Fuses are 3A
> >slow-blow. Overall, the supply makes about 310v, and has powered stereo
> >PP 6B4Gs for years without ever getting hot or behaving at all strangely.
> >Until now.
> >
> >When i turn it on, the rectifier tube gets VERY hot quickly - the plates
> >glow cherry red. After a little while (no longer than 30 seconds), the
> >fuse blows. This seems like a short, so i've systematically disconnected
> >everything downstream or parallel (filament supplies, output xformers,
> >additional filter stages). All that's left is HT to the rectifier tube,
> >then the choke, the cap, and a 330k wirewound resistor from the cap to the
> >ground buss. I've tried swapping rectifiers, caps, even wire. Careful
> >checking with a VOM can't find any unexpected continuities in this
> >simplified circuit. The cap has a charge and is draining normally across
> >the bleed resistor after the fuse blows.
> >
> >So now i suspect the power transformer. Does it seem like i'm on the
> >right track? Please tell me before i have to drill new holes in the>
> >chassis to accomodate a new xformer...
> >--
> >Dave Stagner <dstagner@talkware.net>
> >Universal Talkware Corporation
> >10 Second St. NE Suite 400, Minneapolis MN 55413
> >ph: 612-843-6749 fax: 612-843-6707
> >
>
=========================================================================
From: Roscoe Primrose <roscoe@aiko.com>
Subject: Re: [JN] Bad power tranny?
Date: Wed, 06 Dec 2000 12:30:42 -0500
Source: Sound Digest Archive v02.n753
Dave Stagner wrote:
> On the other hand, if the choke is shorting to its housing, which
> is bolted to the chassis, and only doing so under high voltage conditions,
> that could explain it.
>
This is what I was suggesting as a possibility...
Peace
- --
Roscoe Primrose -- mailto:roscoe@aiko.com --
http://www.aiko.com/roscoe
"Once in a while you get shown the light
In the strangest of places if you look at it right." Robert Hunter
"640K ought to be enough for anybody" , Bill Gates, 1981
=========================================================================
From: AnnaLogg@aol.com
Subject: [JN] Bad URL
Date: Sun, 28 Feb 1999 15:44:59 EST
Source: Sound Digest Archive v02.n064
In a message dated 99-02-28 13:25:40 EST, I wrote:
> Yes, I heard that this group (which is only of interest to US citizens) at
> www.defendyourprivacy.com is an excellent and respected organization. In
> additon to t
Sorry. That URL doesn't work. I was working from an obviously faulty memory
- -- heard it on the radio in the car and wrote it down there; I'll check it out
and repost it (probably tomorrow) for those who are interested.
Anna
=========================================================================
From: DocGaw@cs.com
Subject: [JN] Bad weekend- Blown TAD 2001 and 2002
Date: Sun, 30 Jan 2000 15:17:27 EST
Source: Sound Digest Archive v02.n426
My wife got me to take my equipment apart this weekend to dust behind it. It
didn't really need it, but I did find a two year old magazine I thought I had
lost.
Anyway, on putting the system back together, on turning on the units. I blew
the membranes to t TAD 2001 and a 2002 driver. Does anybody know where I can
purchase them other thanTAD which wants a small fortune?
Bill Gaw
=========================================================================
From: "Peter Empson" <empson@lineone.net>
Subject: [JN] Bahnsen cornerhorns
Date: Tue, 7 Aug 2001 22:08:17 +0100
Source: Sound Digest Archive v02.n941
I have just seen the pictures from the Århus Festival, thanks for posting
them for those of us who couldn't attend (maybe next year...).
Anyway, the photos of the Bahnsen cornerhorns look stunning.
Is there any info about these on the web?
I am curious to know where the bass horn vents, is it from underneath? What
are they made from? What drivers?
Any information would be gratefully received.
Apologies in advance if they have been covered in previous threads.
Peter.
=========================================================================
From: "Peter Empson" <empson@lineone.net>
Subject: Re: [JN] Bahnsen cornerhorns
Date: Tue, 7 Aug 2001 22:59:07 +0100
Source: Sound Digest Archive v02.n941
Bjorn and Jan,
Thanks for the link, I'll go have a look now.
Peter.
=========================================================================
From: =?iso-8859-1?Q?Bj=F8rn_Aaholm?= <boulevarden@get2net.dk>
Subject: SV: [JN] Bahnsen cornerhorns
Date: Tue, 7 Aug 2001 23:23:59 +0200
Source: Sound Digest Archive v02.n941
Hi Peter.
Peter Bahnsen has a website about his horns:
http://www.bahnsenengineering.dk/
The bass horn vents underneath, by the vertical "seperators" you can
see by the floor.
You should find extensive info on his site.
Regards,
Bjørn Aaholm
=========================================================================
From: "John K. Dahlman" <jkdahlman@home.com>
Subject: Re: SV: [JN] Bahnsen cornerhorns
Date: Wed, 8 Aug 2001 00:49:08 -0400
Source: Sound Digest Archive v02.n941
Hi all. Showed my long suffering wife these, and I quote "If you can build
something that looks like that you can have them anywhere in the house you'd
like." The ultimate DIY horn? I gotta try! How often am I going to get the
green light on something like this? Any ideas out there?
Have fun,
John
On Tuesday 07 August 2001 17:23, you wrote:
> Hi Peter.
>
> Peter Bahnsen has a website about his horns:
> http://www.bahnsenengineering.dk/
>
> The bass horn vents underneath, by the vertical "seperators" you can
> see by the floor.
>
> You should find extensive info on his site.
>
> Regards,
> Bjørn Aaholm
=========================================================================
From: Dragos Bora <dsbora@mic.ro>
Subject: [JN] Balanced outputs & inputs and the phase splitter stage
Date: Mon, 16 Aug 1999 18:10:44 +0300
Source: Sound Digest Archive v02.n248
Dear sirs,
I would like to know if it is possible to input the signal from the
balanced ouputs of my DAC (PARASOUND D/AC 1500)
after the phase splitter stage of a push-pull power amplifier, knowing that
the balanced signal is already phase-shifted.
I want to try this in a tube amp and in a solid state one.
I know that problems may appear at least from adapting the impedances.
That's why I am asking if someone has some ideas on this.
Thank you for your kind answer.
Yours much obliged,
Dragos BORA
=========================================================================
From: Grover Gardner <groverg@postoffice.att.net>
Subject: Re: [JN] Balanced outputs & inputs and the phase splitter stage
Date: Tue, 17 Aug 1999 20:50:59 -0400
Source: Sound Digest Archive v02.n250
Dragos, have you looked at TubeCad Journal, the on-line magazine at
www.glassware.com? They have a series of articles on balanced line circuits,
including some comments about using balanced preamps to drive a PP circuit.
- --
Grover Gardner
groverg@postoffice.att.net
=========================================================================
From: Peter Allen <ptrallen@melbpc.org.au>
Subject: [JN] Balanced Power at home
Date: Tue, 02 Feb 1999 14:43:36 +1100
Source: Sound Digest Archive v02.n021
- --=====================_23586565==_.ALT
Content-Type: text/plain; charset="us-ascii"
Guys:
Can we have a brains trust on the feasibility of (getting a registered
electrician to) creating one balanced circuit in a home for audio purposes.
Is it valid, has anyone done it with good results, or is it just a w.... ell a
waste of time?
The naive in me hopes that it only needed a transformer and you could then set
up a
dedicated circuit just for your audio.
Thanks for your considerations.
- -peter
Lance Dow in London started it all off:
If you want to find out about balanced power, check out EquiTech at;
www.equitech.com/
This page has an index to a number of articles on the subject. They're
not too technical and they're well illustrated so you can follow what's
being said.
A year-or-so ago I downloaded and read HUGE amounts on balanced power
from the EquiTech site and spent weeks contemplating a DIY version of their
conditioner. I wasn't sure just how accurately the two phases needed
to be for a start - whether I could use a pair of 240:120 step-downs
with the primaries in parallel and the secondaries in series to give a
centre-tapped 240v (+/- 120v). Or whether I need something more
specialised (both secondaries exactly the same on a common core).
My concern was just how well matched the two halves of the transformer
needed to be. Obvious you get the best result when they match
perfectly, but how far can they slip before you lose it completely?
The articles weren't technical enough to give me this info, nor could
I glean it from the specs of their commercial transformers. My gut
feeling is that you get a large proportion of the benefit by just
having it balanced about earth, with the best cancellation etc coming
when the balance is perfect. Unfortunately, I didn't have a spare
isolation tranny to play around with.
Perhaps the arrangement might contravene local wiring regulations.
Peter Allen: editor, Melbourne Audio Club News
_______________________________________
*25th Anniversary year* Do visit us
http://vicnet.net.au/~macinc
- --=====================_23586565==_.ALT
Content-Type: text/html; charset="us-ascii"
<html>
Guys:<br>
Can we have a brains trust on the feasibility of (getting a registered
electrician to) creating one balanced circuit in a home for audio
purposes. <br>
Is it valid, has anyone done it with good results, or is it just a w....
ell a waste of time?<br>
The naive in me hopes that it only needed a transformer and you could
then set up a <br>
dedicated circuit just for your audio.<br>
<br>
Thanks for your considerations.<br>
- -peter<br>
<br>
Lance Dow in London started it all off: <br>
If you want to find out about balanced power, check out
EquiTech at; <br>
<a href="http://www.equitech.com/" eudora="autourl"><font color="#0000FF"><u>www.equitech.com/
</a></font></u>
<br>
<br>
This page has an index to a number of articles on the subject.
They're <br>
not too technical and they're well illustrated so you can follow
what's <br>
being said.<br>
<br>
A year-or-so ago I downloaded and read HUGE amounts on balanced power
<br>
from the EquiTech site and spent weeks contemplating a DIY version
of their <br>
conditioner. I wasn't sure just how accurately the two phases needed
<br>
to be for a start - whether I could use a pair of 240:120 step-downs
<br>
with the primaries in parallel and the secondaries in series to give a
<br>
centre-tapped 240v (+/- 120v). Or whether I need something more <br>
specialised (both secondaries exactly the same on a common core). <br>
<br>
My concern was just how well matched the two halves of the transformer
<br>
needed to be. Obvious you get the best result when they match <br>
perfectly, but how far can they slip before you lose it completely?
<br>
The articles weren't technical enough to give me this info, nor could
<br>
I glean it from the specs of their commercial transformers. My gut <br>
feeling is that you get a large proportion of the benefit by just <br>
having it balanced about earth, with the best cancellation etc coming
<br>
when the balance is perfect. Unfortunately, I didn't have a spare <br>
isolation tranny to play around with.<br>
<br>
Perhaps the arrangement might contravene local wiring regulations. <br>
<br>
<br>
<br>
<div>Peter Allen: editor, Melbourne Audio Club News</div>
<div>_______________________________________</div>
<div> *25th Anniversary
year*  
;
Do visit us</div>
http://vicnet.net.au/~macinc &n
bsp;
</html>
- --=====================_23586565==_.ALT--
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Balanced Power at home
Date: Tue, 02 Feb 1999 05:39:55 PST
Source: Sound Digest Archive v02.n022
Hi all,
>Can we have a brains trust on the feasibility of (getting a
>registered electrician to) creating one balanced circuit in
>a home for audio purposes.
Why not.
>Is it valid,
Yes.
>has anyone done it with good results,
No-one I know.
>or is it just a w.... ell a waste of time?
Hard to say. All concidered, with suitable treatements to the normal
mains I believe a similar effect can be obtained much cheaper.
>The naive in me hopes that it only needed a transformer
That is correct. But in order not to constrict dynamics of Amplifiers
connect you need a WHOPPING BIG MONSTER Transformer.
I mean not some wimpy 1KVA Unit, but something more close to 5-10KVA.
This will depend upon your Amplifiers of course.
>and you could then set up a dedicated circuit just for your audio.
Sure.
Kind regards Thorsten.
======================================
e-mail:
Thorsten@tnt-audio.com
Visit TNT-Audio on the Web - the only advertising
free audio web-zine.
http://www.tnt-audio.com
======================================
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
=========================================================================
From: David Bardes <David_Bardes@zd.com>
Subject: [JN] Re: Balanced Power at home
Date: Thu, 04 Feb 1999 14:30:44 -0800
Source: Sound Digest Archive v02.n028
Bruce,
May I be so bold as to ask "How Much?$?"
David
>I have gone to a balanced power line. It's quieter more and more details
>come through.
=========================================================================
From: "Bruce Nilson" <bnilson@FCB.COM>
Subject: Re: [JN] Balanced Power at home
Date: Thu, 04 Feb 1999 16:19:36 +0000
Source: Sound Digest Archive v02.n028
I have gone to a balanced power line. It's quieter more and more details
come through.
It goes from 240v to 60-0-60v with some filtering. A true seperate
ground makes the difference.
Another John Camille design.
Bruce Nilson
=========================================================================
From: David Bardes <David_Bardes@zd.com>
Subject: Re: [JN] Re: Balanced Power at home
Date: Thu, 04 Feb 1999 16:19:41 -0800
Source: Sound Digest Archive v02.n028
Ahh, not so bad. Much less expensive than the commercial balanced power
products.
>About $350-$400, using a combination of surplus and new parts.
David
=========================================================================
From: "Bruce Nilson" <bnilson@FCB.COM>
Subject: [JN] Re: Balanced Power at home
Date: Thu, 04 Feb 1999 17:03:06 +0000
Source: Sound Digest Archive v02.n028
- --------------F0A4D2BE321F89DA44F25CED
Content-Type: text/plain; charset=us-ascii; x-mac-type="54455854"; x-mac-creator="4D4F5353"
Content-Transfer-Encoding: 7bit
Bruce,
May I be so bold as to ask "How Much?$?"
David
About $350-$400, using a combination of surplus and new parts.
It's only good for about 4 amps I think.
- --------------F0A4D2BE321F89DA44F25CED
Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: 7bit
<HTML>
<I>Bruce,</I>
<P><I>May I be so bold as to ask "How Much?$?"</I>
<P><I>David</I>
<BR>
<P>About $350-$400, using a combination of surplus and new parts.
<BR>It's only good for about 4 amps I think.</HTML>
- --------------F0A4D2BE321F89DA44F25CED--
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] Balanced Power at home
Date: Thu, 04 Feb 1999 19:58:01 +0100
Source: Sound Digest Archive v02.n028
Why would you like to have a balanced system ?
Are you talking mains ?
Guido
At 14:43 2-2-99 +1100, Peter Allen wrote:
>>>>
<excerpt>Guys:
Can we have a brains trust on the feasibility of (getting a registered
electrician to) creating one balanced circuit in a home for audio
purposes.
Is it valid, has anyone done it with good results, or is it just a w....
ell a waste of time?
The naive in me hopes that it only needed a transformer and you could
then set up a
dedicated circuit just for your audio.
Thanks for your considerations.
- -peter
Lance Dow in London started it all off:
If you want to find out about balanced power, check out EquiTech at;
<<http://www.equitech.com/><underline><color><param>0000,0000,ffff</param>www.equitech.com/</color>
</underline>
This page has an index to a number of articles on the subject. They're
not too technical and they're well illustrated so you can follow what's
being said.
A year-or-so ago I downloaded and read HUGE amounts on balanced power
from the EquiTech site and spent weeks contemplating a DIY version of
their
conditioner. I wasn't sure just how accurately the two phases needed
to be for a start - whether I could use a pair of 240:120 step-downs
with the primaries in parallel and the secondaries in series to give a
centre-tapped 240v (+/- 120v). Or whether I need something more
specialised (both secondaries exactly the same on a common core).
My concern was just how well matched the two halves of the transformer
needed to be. Obvious you get the best result when they match
perfectly, but how far can they slip before you lose it completely?
The articles weren't technical enough to give me this info, nor could
I glean it from the specs of their commercial transformers. My gut
feeling is that you get a large proportion of the benefit by just
having it balanced about earth, with the best cancellation etc coming
when the balance is perfect. Unfortunately, I didn't have a spare
isolation tranny to play around with.
Perhaps the arrangement might contravene local wiring regulations.
Peter Allen: editor, Melbourne Audio Club News
_______________________________________ *25th Anniversary year*
Do visit us
<<http://vicnet.net.au/~macinc>http://vicnet.net.au/~macinc
</excerpt>
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] Balanced Power at home
Date: Sat, 06 Feb 1999 13:33:55 +0100
Source: Sound Digest Archive v02.n030
Hi Joes,
I believe the advantage of another transformer, separating or balancing the
mains, only is exploited if a transformer with low parasytic capacitance is
used
Such transformers can oten be found from the medical industry
Commonly available transformers have relative high capacitance (say up to 1
nF) between primary and secundary and as such have relative low coupling
impedance for common mode currents.
Transformers with a low capacitance behave as a high impedance and therefor
reduce common mode currents
It is my believe and perception that more detail remains resolved
My 2 euro cent
Guido
At 16:19 4-2-99 +0000, Bruce Nilson wrote:
>I have gone to a balanced power line. It's quieter more and more details
>come through.
>It goes from 240v to 60-0-60v with some filtering. A true seperate
>ground makes the difference.
>Another John Camille design.
>
>
>Bruce Nilson
>
>
=========================================================================
From: "Remco Stoutjesdijk" <r.m.stoutjesdijk@student.utwente.nl>
Subject: [JN] balanced riaa preamp questions
Date: Thu, 25 Jan 2001 16:37:46 +0100
Source: Sound Digest Archive v02.n792
Hi,
I'm preparing to build a new balanced riaa preamp, and have a few questions:
- - is it worth it to follow the riaa curve to within, say 0.1 dB? I have a
fairly accurate unit right now, but I notice a lot of tonal differences
between records, especially in the bass region. It seems most records don't
follow the eq curve as well as the preamp. Dare I include some tonal
controls or will that ban me from the Joelist? ;)
- - are there any cool (unusual) designs out there? I have an all-transformer
design from Christian Rintelen and have taken a look at Allen Wright's
designs. These are almost orthagonal, I like that, it yields a lot of
insights. But I'd welcome some more suggestions.
TIA!
Remco
- --
http://listen.to/rmsaudio
=========================================================================
From: Christian Rintelen <christian@rintelen.ch>
Subject: Re: [JN] balanced riaa preamp questions
Date: Thu, 25 Jan 2001 21:24:37 +0100
Source: Sound Digest Archive v02.n793
To do the RIAA *differential i.e. mirrored for both phases* is possible, but
probably not adviseable... If the two RIAAs are not 100% identical, the errors
will add up and you'll deviate more than just 0.1 dB from the RIAA curve.
That's why I chose to leave the fully balanced path and float the LCR-RIAA.
Christian
Remco Stoutjesdijk wrote:
> I'm preparing to build a new balanced riaa preamp, and have a few questions:
>
> - is it worth it to follow the riaa curve to within, say 0.1 dB? I have a
> fairly accurate unit right now, but I notice a lot of tonal differences
> between records, especially in the bass region. It seems most records don't
> follow the eq curve as well as the preamp. Dare I include some tonal
> controls or will that ban me from the Joelist? ;)
=========================================================================
From: "=?ISO-8859-1?Q?Torbj=F8rn_Lien?=" <mdrivekl@online.no>
Subject: [JN] Balanced x-formers/was Help with 300B operating points please...
Date: Sat, 3 Apr 1999 22:51:18 +0200
Source: Sound Digest Archive v02.n108
Hello all
Pearl wrote:
> Hi All:
> The SE phenomena caused me to seriously rethink push-pull
> and I spent several years on that. The upshot is that single
> coil PP OTs are never wound so that they balance.. neither AC
> nor DC. Now, if one of the most crucial parts of the circuit >
simply does not work proporely, the entire can NEVER
> work properly. So, I figured out haw to buil PP OTs that
> ARE balanced. . .easire said than done and by a good long way . .
>
> Bill - PEARL
Ehm,- I'm intruiged! :)
Why don't you share your findings? Are they beond Reuben Lee?!
He did advocate this....(more or less, my interpretation....)
- -Since good pri to pri coupling is never perfect,- class "A"
output stage is the only thing to work with in PP...
- -In class "A" close pri-pricoupling is not essential. So now a
perfectly balanced x-former can be made, if using a
single C/double coil x-former type.
Of course later on there was the voltage-feedback/unity coupling
by McIntosh.And the "in same family" circlotrone-consept from
Electrovoice....
Regards,
T.Lien
>
>
>
=========================================================================
From: "PEARL Cust Serv" <custserv@pearl-hifi.com>
Subject: [JN] Bal'd Pwr, Grnds, Loops and the like
Date: Mon, 08 Feb 1999 18:20:17 -0700
Source: Sound Digest Archive v02.n034
Joes:
Here's a good URL, check it out:
http://www.equitech.com/articles/articles.htm
Bill Perkins, PEARL Inc.
2528 19 St. S.W., Calgary, Ab.,
Canada T2T 4X3
Ph. 1 403 244 4434 Fx. 1 403 244 9026
=========================================================================
From: "Nikita Kamka" <nikita@int.mew.co.jp>
Subject: Re: [JN] balloon 300B
Date: Wed, 6 Dec 2000 08:18:39 +0700
Source: Sound Digest Archive v02.n752
Hi!
- ----- Original Message -----
From: C.snoeren <c.snoeren@tip.nl>
>
> Ps. anyone heared (of) the brand new BALLOON 300B tubes?
>
Do you mean those taiwanese?
They said in japanese list, the soundit is not good, very disappointing,
except the retro-shape (and the price:)
Regards,
Nikita Kamka
=========================================================================
From: Norm Luttbeg <nluttbeg@politics.tamu.edu>
Subject: Re: [JN] balloon 300B
Date: Wed, 06 Dec 2000 13:22:24 -0500
Source: Sound Digest Archive v02.n753
on 12/5/00 8:18 PM, Nikita Kamka at nikita@int.mew.co.jp wrote:
> Hi!
>
> ----- Original Message -----
> From: C.snoeren <c.snoeren@tip.nl>
>>
>> Ps. anyone heared (of) the brand new BALLOON 300B tubes?
>>
>
> Do you mean those taiwanese?
> They said in japanese list, the soundit is not good, very disappointing,
> except the retro-shape (and the price:)
>
> Regards,
> Nikita Kamka
Apparently, AVVT also has a globe 2A3 which is also said to not be the equal
of the ST
Norm
=========================================================================
From: "Quest quest" <hoshum2@hotmail.com>
Subject: Re: [JN] balloon 300B
Date: Thu, 07 Dec 2000 06:55:13 -0800
Source: Sound Digest Archive v02.n755
Fellow Joes!
Yeash! These ballon shaped 300B tubes was originally designed and hand-made
by a Taiwanese Audio Shop owner who got most of his tube-making expertise
from some ex-NEC production line. Initial prototype includes WE205D, etc.
and they all performed well (remember: these are just clones of original WE
300B or WE205D just like any other else).
As he finally decided to mass-produce these tubes he negotiated with a few
ex-mil tube factories in Mainland China (noticeably from TianTsin, China) to
have them made under contract. Things went well and what you see now is the
mass-produced Chinese version of the Taiwanese "Full Music" 300B (original
Taiwanese versions are all hand-made and are not meant to be sold to the
public, mind you).
The very unfortunatly part is, like any other corporate contractors in
mainland, many of these guys also make some extras by going out of quotas
and sell the excess under a different brand name. (this is very common in
mainland these days, from fake shampoo bottles with different stuff other
than the "real" thing in it to fake Duracell batteries to God-knows-what.
Assuming that these balloon shaped tubes are highly popular, these side-line
guys will do anything just to make a buck.
Oh and BTW: from what I understand these tubes have a slightly different
characteristics compared to the original WE300B. I do not have the spec. at
this moment so plse don't ask me for it....
That's all the information I have for now.
Good luck!
Quest;^>
>From: Norm Luttbeg <nluttbeg@politics.tamu.edu>
>To: Nikita Kamka <nikita@int.mew.co.jp>, <c.snoeren@tip.nl>, Joelist
><sound@deliverator.io.com>
>Subject: Re: [JN] balloon 300B
>Date: Wed, 06 Dec 2000 13:22:24 -0500
>
>on 12/5/00 8:18 PM, Nikita Kamka at nikita@int.mew.co.jp wrote:
>
> > Hi!
> >
> > ----- Original Message -----
> > From: C.snoeren <c.snoeren@tip.nl>
> >>
> >> Ps. anyone heared (of) the brand new BALLOON 300B tubes?
> >>
> >
> > Do you mean those taiwanese?
> > They said in japanese list, the soundit is not good, very disappointing,
> > except the retro-shape (and the price:)
> >
> > Regards,
> > Nikita Kamka
>Apparently, AVVT also has a globe 2A3 which is also said to not be the
>equal
>of the ST
>
>Norm
>
_____________________________________________________________________________________
Get more from the Web. FREE MSN Explorer download : http://explorer.msn.com
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: [JN] balloon 300B *More info*
Date: Thu, 7 Dec 00 10:33:06 -0500
Source: Sound Digest Archive v02.n755
Gang,
Just a little more info...
Peter Chang is the person in charge and his email addres is:
allmusic@ms22.hinet.net
The company in Taiwan is AllMusic and the China company is Full Music. As
usual the tubes are only suppose to be All Music branded but we know how
that is. You can get the All Music version of these tubes from New
Sensor. I have the 101 and 205 and the 205 are real sweet but they are a
bit of the norm. Also these use UX-4 style basses insted of the UV-4
bases used in the original items (arg......).
The NOV issue of MJ has all the specs and differences for the tubes.
Gordon
>Yeash! These ballon shaped 300B tubes was originally designed and hand-made
>by a Taiwanese Audio Shop owner who got most of his tube-making expertise
>from some ex-NEC production line. Initial prototype includes WE205D, etc.
>and they all performed well (remember: these are just clones of original WE
>300B or WE205D just like any other else).
>
> As he finally decided to mass-produce these tubes he negotiated with a few
>ex-mil tube factories in Mainland China (noticeably from TianTsin, China) to
>have them made under contract. Things went well and what you see now is the
>mass-produced