Sound Practices Mailing List Files - Volume 2
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: Re: [JN] 90 degree generation
Date: Sat, 17 Jun 2000 08:18:10 -0700
Source: Sound Digest Archive v02.n583
Hi All,
I haven't been following this thread closely and this may not be
relevant information pertaining the task at hand, but it would seem
appropriate to derive the three-phase signals using standard logic with
the apropriate filtering to turn the squarewaves to something resembling
sinewaves.
First 90 degree signals. A stable and reliable means for generating 90
degree signals is to use a twisted ring counter driven by a four-times
frequency source. This will give you all four phases directly without
any decoding and they are symmetrical signals. The outputs obviously
need some filtering if a sinewave signal is required. However, a motor
would likely be happy with squarewave drive, especially if driven by a
current source such as transistor collectors where the inductance of the
motor winding would do much of the filtering.
A twisted ring counter, for those not familiar, consists simply of JK
flipflops (FF) with the outputs connected to the inputs of the next
stage (Q to J and Qbar to K), then the outputs of the final FF
connected back around to the first FF except with the phase reversed (Q
to K and Qbar to J). The clock then is driven by a frequency N times
the divide integer (where N is the divide integer). As I recall, a
twisted ring counter divides by N-1 times the number of FFs (where N is
the number of stages). I haven't thought about it much for the past 25
or 30 years, but this is the general approach. Hmm, something bothers
me about that, as I seem to recall that two dual JK flipflops would
divide by four. Anyway, I have a little Siliconix book around somewhere
that goes into detail, if anyone is interested in more details.
A divide by six counter could be made in this manner to derive the 120
degree phase signals. I don't recall at the moment whether symmetrical
120 degree signals are available directly from the divide-by-six twisted
ring counter outputs. If not, they could be derived with simple logic
gating, or for that matter, from any divide-by-six counter. If decoding
is necessary, one of the programable divider chips would be a better
choice.
I once learned a very slick method of designing
quasi-random-count-sequence synchronous clocked counters. Using this
method synchronous counters could be easily and quickly designed for any
desired count sequence. This method allowed a counter to be designed to
generate a specific waveform directly eliminating the requirement for
output decoding. The method involved deriving some simple equations
specific to FF types (such as D, JK, etc) which were then multipliplied
with a Vietch diagram to derive the equations defining the counter
gating, directly. The Veitch diagram contained the desired count
sequence. Using this method, a simple counter could be quickly
designed which would give the three symmetrical phases directly from the
FF outputs without decoding. Another advantage was that designs for all
flipflop types could be quickly derived and the type yielding the most
simple gating could be specified for the final design. However, the
availability of programmable integrated counter chips quickly eliminated
the need for such design techniques. I would have to dig out my notes
on that as this was something I learned way back in the sixties and
never used much. It was so absolutely clever at the time that it amazed
even experienced senior logic designers. We were designing a color TV
sync generator at the time and it seemed appropriate to design the
divide chain to derive all the required pulses in the most simple
manner. Most Yahoos at the time would use ripple counters (ugh) and
decode logic. The sync generator chips became available around that
time, so the design was never completed.
If it turns out that the twisted ring counter gives the proper
three-phase signals directly then this would probably be the better way
to go. Sorry for the lack of precise details, but I am reaching back a
long time trying to remember something that I barely used even then.
Dan Marshall
=========================================================================
From: Tim Reese <tgrmail@nmr.MGH.harvard.EDU>
Subject: Re: [JN] 90 degree generation
Date: Sat, 17 Jun 2000 16:13:32 -0400 (EDT)
Source: Sound Digest Archive v02.n583
FWIW there is a digital synchronous motor drive circuit in Horowitz and
Hill "The Art of Electronics" that could be easily adapted to drive in
multiphase using flip-flop dividers (as suggested by Dan). Look for the
observatory dome motor controller.
hth tr
- ----------------------------------------------------------------------
Visit http://www.nmr.MGH.harvard.edu/~reese MRI, tube audio, reptiles
Tim Reese, MGH NMR Center reese@nmr.MGH.harvard.edu
=========================================================================
From: tube@jump.net
Subject: Re: [JN] 90 degree generation
Date: Sat, 17 Jun 2000 23:15:13 -0500
Source: Sound Digest Archive v02.n584
My idea along this line was to use a three stage Johnson counter, send
the output from each section to a flip-flop to "square up" the 3
outputs, and then phase-lock 3 sine-wave generators to the outputs.
That way you would have a pure sine-wave (turning square waves into
sine waves is not easy from what I can see). A single square wave
generator would then control the frequency of the 3 outputs, which
would be guaranteed to be 120 degrees apart. I didn't know if I could
get the phase locks workings, however, and 3 separate sine wave
generators sounded like a lot of work, so I abandoned the idea. You
appear to have several additional ideas for generating the signals, if
I understand you correctly.
We should probably keep all of these ideas in mind, because as this
list has shown, several heads brainstorming together usually produce
the best solutions!
Thanks,
Phil
"Daniel J. Marshall" wrote:
> Hi All,
>
> I haven't been following this thread closely and this may not be
> relevant information pertaining the task at hand, but it would seem
> appropriate to derive the three-phase signals using standard logic with
> the apropriate filtering to turn the squarewaves to something resembling
> sinewaves.
>
> First 90 degree signals. A stable and reliable means for generating 90
> degree signals is to use a twisted ring counter driven by a four-times
> frequency source. This will give you all four phases directly without
> any decoding and they are symmetrical signals. The outputs obviously
> need some filtering if a sinewave signal is required. However, a motor
> would likely be happy with squarewave drive, especially if driven by a
> current source such as transistor collectors where the inductance of the
> motor winding would do much of the filtering.
>
> A twisted ring counter, for those not familiar, consists simply of JK
> flipflops (FF) with the outputs connected to the inputs of the next
> stage (Q to J and Qbar to K), then the outputs of the final FF
> connected back around to the first FF except with the phase reversed (Q
> to K and Qbar to J). The clock then is driven by a frequency N times
> the divide integer (where N is the divide integer). As I recall, a
> twisted ring counter divides by N-1 times the number of FFs (where N is
> the number of stages). I haven't thought about it much for the past 25
> or 30 years, but this is the general approach. Hmm, something bothers
> me about that, as I seem to recall that two dual JK flipflops would
> divide by four. Anyway, I have a little Siliconix book around somewhere
> that goes into detail, if anyone is interested in more details.
>
> A divide by six counter could be made in this manner to derive the 120
> degree phase signals. I don't recall at the moment whether symmetrical
> 120 degree signals are available directly from the divide-by-six twisted
> ring counter outputs. If not, they could be derived with simple logic
> gating, or for that matter, from any divide-by-six counter. If decoding
> is necessary, one of the programable divider chips would be a better
> choice.
>
> I once learned a very slick method of designing
> quasi-random-count-sequence synchronous clocked counters. Using this
> method synchronous counters could be easily and quickly designed for any
> desired count sequence. This method allowed a counter to be designed to
> generate a specific waveform directly eliminating the requirement for
> output decoding. The method involved deriving some simple equations
> specific to FF types (such as D, JK, etc) which were then multipliplied
> with a Vietch diagram to derive the equations defining the counter
> gating, directly. The Veitch diagram contained the desired count
> sequence. Using this method, a simple counter could be quickly
> designed which would give the three symmetrical phases directly from the
> FF outputs without decoding. Another advantage was that designs for all
> flipflop types could be quickly derived and the type yielding the most
> simple gating could be specified for the final design. However, the
> availability of programmable integrated counter chips quickly eliminated
> the need for such design techniques. I would have to dig out my notes
> on that as this was something I learned way back in the sixties and
> never used much. It was so absolutely clever at the time that it amazed
> even experienced senior logic designers. We were designing a color TV
> sync generator at the time and it seemed appropriate to design the
> divide chain to derive all the required pulses in the most simple
> manner. Most Yahoos at the time would use ripple counters (ugh) and
> decode logic. The sync generator chips became available around that
> time, so the design was never completed.
>
> If it turns out that the twisted ring counter gives the proper
> three-phase signals directly then this would probably be the better way
> to go. Sorry for the lack of precise details, but I am reaching back a
> long time trying to remember something that I barely used even then.
>
> Dan Marshall
=========================================================================
From: TubeGarden@aol.com
Subject: Re: [JN] 90 degree generation
Date: Sun, 18 Jun 2000 00:57:08 EDT
Source: Sound Digest Archive v02.n584
In a message dated 6/17/00 9:22:41 PM US Mountain Standard Time,
tube@jump.net writes:
> three stage Johnson counter
Man,
Having ONE three stage Johnson should be enough for anyone!
Al
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: Re: [JN] 90 degree generation
Date: Sun, 18 Jun 2000 11:01:12 -0700
Source: Sound Digest Archive v02.n584
> Why bother with the phaselocking? Just pass the 3 digital signals
> through "matched" low pass filters, like the switched-cap variety. These
> are usually spec'ed to be within a percent or 2, which should be fine.
>
> JL
Yes, that what I would do. I thought of suggesting this, but recall
someone suggesting a very wide frequency range as a requirement which
makes the low pass filters a bit of a pain to deal with, but probably
less than trying to phase lock three oscillators over a wide range. For
a phono drive motor, I am not sure why a wide range would be
necessary. Low pass filters are a snap and can be derived in minutes
using tables from Geffe's filter book "Simplified Modern Filter
Design". Only simple math is required.
On a similar note, a very low distortion fixed-frequency sine wave can
be made, for things like distortion measurements, by designing a 600 ohm
elliptic-function (Cauer) filter connected directly to the 600 ohm sig
gen output. The cutoff frequency can be selected to where the first
null occurs at the 2nd harmonic, then the following nulls predistorted
to occur at the highter harmonics. The rejection at the null points is
extremely high. If you start with a low distortion generator such as
the 200CD, or the like, distortion will be below the threshold of
measurement for most spectrum ananlyzers.
DM
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] 90 degree generation
Date: Sun, 18 Jun 2000 11:09:22 -0400
Source: Sound Digest Archive v02.n584
tube@jump.net wrote:
>
> My idea along this line was to use a three stage Johnson counter, send
> the output from each section to a flip-flop to "square up" the 3
> outputs, and then phase-lock 3 sine-wave generators to the outputs.
> That way you would have a pure sine-wave (turning square waves into
> sine waves is not easy from what I can see). A single square wave
> generator would then control the frequency of the 3 outputs, which
> would be guaranteed to be 120 degrees apart. I didn't know if I could
> get the phase locks workings, however, and 3 separate sine wave
> generators sounded like a lot of work, so I abandoned the idea. You
> appear to have several additional ideas for generating the signals, if
> I understand you correctly.
Why bother with the phaselocking? Just pass the 3 digital signals
through "matched" low pass filters, like the switched-cap variety. These
are usually spec'ed to be within a percent or 2, which should be fine.
JL
>
> We should probably keep all of these ideas in mind, because as this
> list has shown, several heads brainstorming together usually produce
> the best solutions!
>
> Thanks,
> Phil
>
> "Daniel J. Marshall" wrote:
>
> > Hi All,
> >
> > I haven't been following this thread closely and this may not be
> > relevant information pertaining the task at hand, but it would seem
> > appropriate to derive the three-phase signals using standard logic with
> > the apropriate filtering to turn the squarewaves to something resembling
> > sinewaves.
> >
> > First 90 degree signals. A stable and reliable means for generating 90
> > degree signals is to use a twisted ring counter driven by a four-times
> > frequency source. This will give you all four phases directly without
> > any decoding and they are symmetrical signals. The outputs obviously
> > need some filtering if a sinewave signal is required. However, a motor
> > would likely be happy with squarewave drive, especially if driven by a
> > current source such as transistor collectors where the inductance of the
> > motor winding would do much of the filtering.
> >
> > A twisted ring counter, for those not familiar, consists simply of JK
> > flipflops (FF) with the outputs connected to the inputs of the next
> > stage (Q to J and Qbar to K), then the outputs of the final FF
> > connected back around to the first FF except with the phase reversed (Q
> > to K and Qbar to J). The clock then is driven by a frequency N times
> > the divide integer (where N is the divide integer). As I recall, a
> > twisted ring counter divides by N-1 times the number of FFs (where N is
> > the number of stages). I haven't thought about it much for the past 25
> > or 30 years, but this is the general approach. Hmm, something bothers
> > me about that, as I seem to recall that two dual JK flipflops would
> > divide by four. Anyway, I have a little Siliconix book around somewhere
> > that goes into detail, if anyone is interested in more details.
> >
> > A divide by six counter could be made in this manner to derive the 120
> > degree phase signals. I don't recall at the moment whether symmetrical
> > 120 degree signals are available directly from the divide-by-six twisted
> > ring counter outputs. If not, they could be derived with simple logic
> > gating, or for that matter, from any divide-by-six counter. If decoding
> > is necessary, one of the programable divider chips would be a better
> > choice.
> >
> > I once learned a very slick method of designing
> > quasi-random-count-sequence synchronous clocked counters. Using this
> > method synchronous counters could be easily and quickly designed for any
> > desired count sequence. This method allowed a counter to be designed to
> > generate a specific waveform directly eliminating the requirement for
> > output decoding. The method involved deriving some simple equations
> > specific to FF types (such as D, JK, etc) which were then multipliplied
> > with a Vietch diagram to derive the equations defining the counter
> > gating, directly. The Veitch diagram contained the desired count
> > sequence. Using this method, a simple counter could be quickly
> > designed which would give the three symmetrical phases directly from the
> > FF outputs without decoding. Another advantage was that designs for all
> > flipflop types could be quickly derived and the type yielding the most
> > simple gating could be specified for the final design. However, the
> > availability of programmable integrated counter chips quickly eliminated
> > the need for such design techniques. I would have to dig out my notes
> > on that as this was something I learned way back in the sixties and
> > never used much. It was so absolutely clever at the time that it amazed
> > even experienced senior logic designers. We were designing a color TV
> > sync generator at the time and it seemed appropriate to design the
> > divide chain to derive all the required pulses in the most simple
> > manner. Most Yahoos at the time would use ripple counters (ugh) and
> > decode logic. The sync generator chips became available around that
> > time, so the design was never completed.
> >
> > If it turns out that the twisted ring counter gives the proper
> > three-phase signals directly then this would probably be the better way
> > to go. Sorry for the lack of precise details, but I am reaching back a
> > long time trying to remember something that I barely used even then.
> >
> > Dan Marshall
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] 90 degree generation
Date: Mon, 19 Jun 2000 08:39:52 -0400
Source: Sound Digest Archive v02.n585
"Daniel J. Marshall" wrote:
>
> > Why bother with the phaselocking? Just pass the 3 digital signals
> > through "matched" low pass filters, like the switched-cap variety. These
> > are usually spec'ed to be within a percent or 2, which should be fine.
> >
> > JL
>
> Yes, that what I would do. I thought of suggesting this, but recall
> someone suggesting a very wide frequency range as a requirement which
> makes the low pass filters a bit of a pain to deal with, but probably
> less than trying to phase lock three oscillators over a wide range. For
> a phono drive motor, I am not sure why a wide range would be
> necessary. Low pass filters are a snap and can be derived in minutes
> using tables from Geffe's filter book "Simplified Modern Filter
> Design". Only simple math is required.
I suppose one could be really clever and figure out how to clock a
switched-cap filter from the same master oscillator that's generating
the drive signals.
JL
>
> On a similar note, a very low distortion fixed-frequency sine wave can
> be made, for things like distortion measurements, by designing a 600 ohm
> elliptic-function (Cauer) filter connected directly to the 600 ohm sig
> gen output. The cutoff frequency can be selected to where the first
> null occurs at the 2nd harmonic, then the following nulls predistorted
> to occur at the highter harmonics. The rejection at the null points is
> extremely high. If you start with a low distortion generator such as
> the 200CD, or the like, distortion will be below the threshold of
> measurement for most spectrum ananlyzers.
>
> DM
=========================================================================
From: Allen Wright <AllenVSE@compuserve.com>
Subject: [JN] 90 degree generation for TT sync motor
Date: Fri, 16 Jun 2000 06:21:42 -0400
Source: Sound Digest Archive v02.n581
Gang,
Someone recently (J-M leC?) was asking for a way to do this accurately
- - I found a simple circuit in a back issue of Electronics World.
If you contact me off line and supply a fax # I'll fax you the concept.
Allen (VSE)
=========================================================================
From: tube@jump.net
Subject: Re: [JN] 90 degree generation for TT sync motor
Date: Fri, 16 Jun 2000 10:04:35 -0500
Source: Sound Digest Archive v02.n581
Allen,
J-M wanted 3 signals, 120 degrees between each, and I thought it could
be done by using 2 90 degree signals to generate the 3 signals. I still
think it can be done, but it will take me a while to do it. The hard
part is to get variable frequency and variable amplitude, both of which
would be nice for turntables. I'm still open to suggestion, however
since I could also use a 3-phase supply. I don't have a "convenient"
fax #, but since the UT library is nearby, you could just post the year
and issue of Electronics World, and I can look it up next time I go
there!
Thanks,
Phil
Allen Wright wrote:
> Gang,
> Someone recently (J-M leC?) was asking for a way to do this accurately
> - I found a simple circuit in a back issue of Electronics World.
>
> If you contact me off line and supply a fax # I'll fax you the concept.
>
> Allen (VSE)
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] 90 degree generation for TT sync motor
Date: Fri, 16 Jun 2000 12:10:30 -0400
Source: Sound Digest Archive v02.n581
There was a reference in PCIM magazine to patent #6,040,989 that
supposedly generates a 3-phase signal from 2 PWM chips. I haven't
checked it out myself.
JL
tube@jump.net wrote:
>
> Allen,
>
> J-M wanted 3 signals, 120 degrees between each, and I thought it could
> be done by using 2 90 degree signals to generate the 3 signals. I still
> think it can be done, but it will take me a while to do it. The hard
> part is to get variable frequency and variable amplitude, both of which
> would be nice for turntables. I'm still open to suggestion, however
> since I could also use a 3-phase supply. I don't have a "convenient"
> fax #, but since the UT library is nearby, you could just post the year
> and issue of Electronics World, and I can look it up next time I go
> there!
>
> Thanks,
> Phil
>
> Allen Wright wrote:
>
> > Gang,
> > Someone recently (J-M leC?) was asking for a way to do this accurately
> > - I found a simple circuit in a back issue of Electronics World.
> >
> > If you contact me off line and supply a fax # I'll fax you the concept.
> >
> > Allen (VSE)
=========================================================================
From: Martin/Campbell family <martincampbell@apex.net.au>
Subject: Re: [JN] 90 degree generation for TT sync motor
Date: Sat, 17 Jun 2000 12:10:41 +1000
Source: Sound Digest Archive v02.n582
I have some chips that generate low distortion, stable sine waves with 90
degree shifts. The frequency is selected with different capacitor values.
I had planned to make a Lingo-like power supply for my Linn Sondek but now
am using a different TT. I am happy to sell the chips and other bits and
pieces and throw in the literature I collected on this to anyone who wants
to finish off my abandoned project. I had planned to have fixed caps to
generate one speed (45rpm) and switches to parallel some other caps to get a
lower frequency for 33rpm. The two signals were then to go to two small
power opamps which would drive the low voltage windings of two small
toroidal mains transformers to get the higher voltages for the motor
windings.
- --
Peter Campbell
=========================================================================
From: Christian Rintelen <rintelen@datacomm.ch>
Subject: Re: [JN] 90 degree generation for TT sync motor
Date: Sat, 17 Jun 2000 14:44:58 +0200
Source: Sound Digest Archive v02.n582
You may want to check how it's done on the pulley-driven EMT turntables; they
have 3-phase AC motors. Check out this japanese site with the original
schematic: http://www2.cds.ne.jp/~yogawa/emt930/emt930_CIRCUIT.gif
Christian
tube@jump.net wrote:
> Allen,
>
> J-M wanted 3 signals, 120 degrees between each, and I thought it could
> be done by using 2 90 degree signals to generate the 3 signals. I still
> think it can be done, but it will take me a while to do it. The hard
> part is to get variable frequency and variable amplitude, both of which
> would be nice for turntables. I'm still open to suggestion, however
> since I could also use a 3-phase supply. I don't have a "convenient"
> fax #, but since the UT library is nearby, you could just post the year
> and issue of Electronics World, and I can look it up next time I go
> there!
>
> Thanks,
> Phil
>
> Allen Wright wrote:
>
> > Gang,
> > Someone recently (J-M leC?) was asking for a way to do this accurately
> > - I found a simple circuit in a back issue of Electronics World.
> >
> > If you contact me off line and supply a fax # I'll fax you the concept.
> >
> > Allen (VSE)
- --
Konzept und Text: Christian Rintelen
Dufourstrasse 165 - CH-8008 Zurich - Switzerland
Voice: +41 1 420 11 55 - Fax: +41 1 420 11 57
mailto:rintelen@datacomm.ch
=========================================================================
From: tube@jump.net
Subject: Re: [JN] 90 degree generation for TT sync motor
Date: Sat, 17 Jun 2000 22:10:42 -0500
Source: Sound Digest Archive v02.n584
Thanks, I will remember that in case I can't get the integrator method
going. Of course, if I can't do that I may not be able to do the PWM
method either!
Phil
John Levreault wrote:
> There was a reference in PCIM magazine to patent #6,040,989 that
> supposedly generates a 3-phase signal from 2 PWM chips. I haven't
> checked it out myself.
>
> JL
>
> tube@jump.net wrote:
> >
> > Allen,
> >
> > J-M wanted 3 signals, 120 degrees between each, and I thought it could
> > be done by using 2 90 degree signals to generate the 3 signals. I still
> > think it can be done, but it will take me a while to do it. The hard
> > part is to get variable frequency and variable amplitude, both of which
> > would be nice for turntables. I'm still open to suggestion, however
> > since I could also use a 3-phase supply. I don't have a "convenient"
> > fax #, but since the UT library is nearby, you could just post the year
> > and issue of Electronics World, and I can look it up next time I go
> > there!
> >
> > Thanks,
> > Phil
> >
> > Allen Wright wrote:
> >
> > > Gang,
> > > Someone recently (J-M leC?) was asking for a way to do this accurately
> > > - I found a simple circuit in a back issue of Electronics World.
> > >
> > > If you contact me off line and supply a fax # I'll fax you the concept.
> > >
> > > Allen (VSE)
=========================================================================
From: tube@jump.net
Subject: Re: [JN] 90 degree generation for TT sync motor
Date: Sat, 17 Jun 2000 22:21:53 -0500
Source: Sound Digest Archive v02.n584
Would those be the Burr-Brown 4423 quadrature oscillators? Nice chips,
and now expensive (I saw $70) now that they are no longer made! These
can be simulated with the normal state-variable active filters, albeit
without the nice on-chip matched capacitors. These will probably work
for someone who wants to have just one or two frequencies, with a
limited adjustment range. I'm hoping to get a range from 2 Hz to 200
kHz, which will probably need a different arrangement, so I will have
to pass myself.
Thanks,
Phil
Martin/Campbell family wrote:
> I have some chips that generate low distortion, stable sine waves with 90
> degree shifts. The frequency is selected with different capacitor values.
> I had planned to make a Lingo-like power supply for my Linn Sondek but now
> am using a different TT. I am happy to sell the chips and other bits and
> pieces and throw in the literature I collected on this to anyone who wants
> to finish off my abandoned project. I had planned to have fixed caps to
> generate one speed (45rpm) and switches to parallel some other caps to get a
> lower frequency for 33rpm. The two signals were then to go to two small
> power opamps which would drive the low voltage windings of two small
> toroidal mains transformers to get the higher voltages for the motor
> windings.
> --
> Peter Campbell
=========================================================================
From: tube@jump.net
Subject: Re: [JN] 90 degree generation for TT sync motor
Date: Sat, 17 Jun 2000 22:32:39 -0500
Source: Sound Digest Archive v02.n584
Wow! That's very interesting. Not just because of the circuit, which I
mostly can't understand, but because of the 3-phase motor. I read just
recently that 3-phase motors and generators have (theoretically) zero
cogging and pulsing, because the 3 phases always balance each other in
terms of pushing and pulling. Apparently 3-phase generators are a LOT
smoother in operation than single phase generators. I just assumed,
however, that all 3-phase motors were large, and therefore not really
suited for turntables. Apparently not! Who knows, maybe this will turn
out to be the best solution in terms of getting the smoothest motor
operation.
Phil
Christian Rintelen wrote:
> You may want to check how it's done on the pulley-driven EMT turntables; they
> have 3-phase AC motors. Check out this japanese site with the original
> schematic: http://www2.cds.ne.jp/~yogawa/emt930/emt930_CIRCUIT.gif
> Christian
>
> tube@jump.net wrote:
>
> > Allen,
> >
> > J-M wanted 3 signals, 120 degrees between each, and I thought it could
> > be done by using 2 90 degree signals to generate the 3 signals. I still
> > think it can be done, but it will take me a while to do it. The hard
> > part is to get variable frequency and variable amplitude, both of which
> > would be nice for turntables. I'm still open to suggestion, however
> > since I could also use a 3-phase supply. I don't have a "convenient"
> > fax #, but since the UT library is nearby, you could just post the year
> > and issue of Electronics World, and I can look it up next time I go
> > there!
> >
> > Thanks,
> > Phil
> >
> > Allen Wright wrote:
> >
> > > Gang,
> > > Someone recently (J-M leC?) was asking for a way to do this accurately
> > > - I found a simple circuit in a back issue of Electronics World.
> > >
> > > If you contact me off line and supply a fax # I'll fax you the concept.
> > >
> > > Allen (VSE)
>
> --
> Konzept und Text: Christian Rintelen
> Dufourstrasse 165 - CH-8008 Zurich - Switzerland
> Voice: +41 1 420 11 55 - Fax: +41 1 420 11 57
> mailto:rintelen@datacomm.ch
=========================================================================
From: "Christian Rintelen"<rintelen@datacomm.ch>
Subject: Re: [JN] 90 degree generation for TT sync motor
Date: Sun, 18 Jun 2000 11:00:47 MEST
Source: Sound Digest Archive v02.n584
The description "small" doesn't really fit on the EMT's motor - it's approx 3"
in diameter and 4 1/2 inches long; output power must be around 1 HP.... Others
would drive a vacuum cleaner with such a beast! The EMTs are definitely over-engineered
by today's standards. However, if you have an idler wheel driving your platter,
you better want something dead quiet...
In the mid 80s EMT's sister company Thorens used a smaller 3-phase AC motor
on their belt driven Reference turntable, this time with an electronic circuit
generating the 3 phases from 1-phase 230 VAC.
I've never heard of a broken EMT's phase "generator" (no wonder - look at how
simple it was done!) whereas the Thorens' electronic 3-phase-generator had a
reputation of braking and running out of adjustment. Looks as if progress led
in the wrong way once again...
Christian
>Wow! That's very interesting. Not just because of the circuit, which I
>mostly can't understand, but because of the 3-phase motor. I read just
>recently that 3-phase motors and generators have (theoretically) zero
>cogging and pulsing, because the 3 phases always balance each other in
>terms of pushing and pulling. Apparently 3-phase generators are a LOT
>smoother in operation than single phase generators. I just assumed,
>however, that all 3-phase motors were large, and therefore not really
>suited for turntables. Apparently not! Who knows, maybe this will turn
>out to be the best solution in terms of getting the smoothest motor
>operation.
>
>Phil
>
>Christian Rintelen wrote:
>
>> You may want to check how it's done on the pulley-driven EMT turntables;
they
>> have 3-phase AC motors. Check out this japanese site with the original
>> schematic: http://www2.cds.ne.jp/~yogawa/emt930/emt930_CIRCUIT.gif
>> Christian
>>
>> tube@jump.net wrote:
>>
>> > Allen,
>> >
>> > J-M wanted 3 signals, 120 degrees between each, and I thought it could
>> > be done by using 2 90 degree signals to generate the 3 signals. I still
>> > think it can be done, but it will take me a while to do it. The hard
>> > part is to get variable frequency and variable amplitude, both of which
>> > would be nice for turntables. I'm still open to suggestion, however
>> > since I could also use a 3-phase supply. I don't have a "convenient"
>> > fax #, but since the UT library is nearby, you could just post the year
>> > and issue of Electronics World, and I can look it up next time I go
>> > there!
>> >
>> > Thanks,
>> > Phil
>> >
>> > Allen Wright wrote:
>> >
>> > > Gang,
>> > > Someone recently (J-M leC?) was asking for a way to do this accurately
>> > > - I found a simple circuit in a back issue of Electronics World.
>> > >
>> > > If you contact me off line and supply a fax # I'll fax you the concept.
>> > >
>> > > Allen (VSE)
=========================================================================
From: Martin/Campbell family <martincampbell@apex.net.au>
Subject: Re: [JN] 90 degree generation for TT sync motor
Date: Mon, 19 Jun 2000 09:33:01 +1000
Source: Sound Digest Archive v02.n584
They are from Thaler Corp.
- --
Peter Campbell
> From: tube@jump.net
> Date: Sat, 17 Jun 2000 22:21:53 -0500
> To: Martin/Campbell family <martincampbell@apex.net.au>
> Cc: sound@lists.io.com
> Subject: Re: [JN] 90 degree generation for TT sync motor
>
> Would those be the Burr-Brown 4423 quadrature oscillators? Nice chips,
> and now expensive (I saw $70) now that they are no longer made! These
> can be simulated with the normal state-variable active filters, albeit
> without the nice on-chip matched capacitors. These will probably work
> for someone who wants to have just one or two frequencies, with a
> limited adjustment range. I'm hoping to get a range from 2 Hz to 200
> kHz, which will probably need a different arrangement, so I will have
> to pass myself.
>
> Thanks,
> Phil
>
> Martin/Campbell family wrote:
>
>> I have some chips that generate low distortion, stable sine waves with 90
>> degree shifts. The frequency is selected with different capacitor values.
>> I had planned to make a Lingo-like power supply for my Linn Sondek but now
>> am using a different TT. I am happy to sell the chips and other bits and
>> pieces and throw in the literature I collected on this to anyone who wants
>> to finish off my abandoned project. I had planned to have fixed caps to
>> generate one speed (45rpm) and switches to parallel some other caps to get a
>> lower frequency for 33rpm. The two signals were then to go to two small
>> power opamps which would drive the low voltage windings of two small
>> toroidal mains transformers to get the higher voltages for the motor
>> windings.
>> --
>> Peter Campbell
>
=========================================================================
From: "Mai, Jeff" <Jeff.Mai@sunmed.com>
Subject: [JN] 90's music (was New sound studio)
Date: Thu, 17 Aug 2000 10:37:07 -0600
Source: Sound Digest Archive v02.n630
The Soft Bulletin was a great album! For those interested in popular music,
here are some personal favorites from the past decade you may have missed:
My Bloody Valentine - Loveless
This topped a number of "best of the decade" lists I've come across. I feel
it's worthy of the praise. It is usually pigeonholed with "shoegazing" but
it doesn't deserve to be judged by that categorization.
Spiritualized - Lazer Guided Melodies - Pure Phase - Ladies and gentlemen we
are floating in space
Any of the three are beautiful masterpieces. If you only check out one
selection from this short list, make it one of these three.
Mercury Rev - Yerself Is Steam - Deserter's Songs
If you liked The Soft Bulletin, check out Deserter's Songs. It was produced
by a member of the Lips. Yerself Is Steam (which was deleted but may be
reissued) is a must if you're into psychedelic music.
Massive Attack - Mezzanine
This one blots out all light! Murky. A very punchy and satisfying trip hop
record.
Portishead - Dummy - ( self titled )
These (along with the Bjork albums) are the records that expanded my
horizons beyond straight ahead rock music.
Bjork - Post - Homogenic
Very innovative electronic pop!
Strangely, these all pretty much slid below the radar screen here in the US,
but were acclaimed elsewhere.
Anyone else have any recommendations?
=========================================================================
From: "Henry Platt" <hnplatt@massed.net>
Subject: Re: [JN] 90's music (was New sound studio)
Date: Thu, 17 Aug 2000 14:23:35 -0400
Source: Sound Digest Archive v02.n631
Hi.
Mr. Bungle - "California" 99 release. Amazing. I love the song entitled
"The Holy Filament" ;-) I didn't think they could do it live but they pulled
it off at Lupo's in Providence. Mike Patten is something else. Their second
mid-nineties CD whose name escapes me is also fantatic.
Also The High Llamas - "Snowbug" and "Cold and Bouncy"
A very tripped out (Haven't used that phrase in about three decades!) UK
based group that seems to have been influenced somewhat by Brian Wilson's
late 60's
post Pet Sounds stuff. Very well recorded with live instruments and all
kinds of analog synth burblings and warblings. Very strange stuff that
sounds amazing in triode. These are both available on limited edition LP's
and are worth seeking out, to quote a line from The High Llamas.
Henry Platt
- ----------
>From: "Mai, Jeff" <Jeff.Mai@sunmed.com>
>To: sound@lists.io.com
>Subject: [JN] 90's music (was New sound studio)
>Date: Thu, Aug 17, 2000, 12:37 PM
>
> The Soft Bulletin was a great album! For those interested in popular music,
> here are some personal favorites from the past decade you may have missed:
>
> My Bloody Valentine - Loveless
> This topped a number of "best of the decade" lists I've come across. I feel
> it's worthy of the praise. It is usually pigeonholed with "shoegazing" but
> it doesn't deserve to be judged by that categorization.
>
> Spiritualized - Lazer Guided Melodies - Pure Phase - Ladies and gentlemen we
> are floating in space
> Any of the three are beautiful masterpieces. If you only check out one
> selection from this short list, make it one of these three.
>
> Mercury Rev - Yerself Is Steam - Deserter's Songs
> If you liked The Soft Bulletin, check out Deserter's Songs. It was produced
> by a member of the Lips. Yerself Is Steam (which was deleted but may be
> reissued) is a must if you're into psychedelic music.
>
> Massive Attack - Mezzanine
> This one blots out all light! Murky. A very punchy and satisfying trip hop
> record.
>
> Portishead - Dummy - ( self titled )
> These (along with the Bjork albums) are the records that expanded my
> horizons beyond straight ahead rock music.
>
> Bjork - Post - Homogenic
> Very innovative electronic pop!
>
> Strangely, these all pretty much slid below the radar screen here in the US,
> but were acclaimed elsewhere.
>
> Anyone else have any recommendations?
>
>
=========================================================================
From: TubeGarden@aol.com
Subject: Re: [JN] 90's music (was New sound studio)
Date: Thu, 17 Aug 2000 15:48:17 EDT
Source: Sound Digest Archive v02.n631
Hi Joes,
I enjoy the rec.audio.pro R.A.P. CD in BLUE set. Lots of cosmological band
width. solo width, too
Also Joni Mitchell's both sides now - more sound, less processing
bass extreme cookbook is two electric bass players - really shows off my
hundreds of milliwatts
global warming - sonny rollins has more fun than even rudy village gate can
capture
the CDs that come with BBC, Music, Classical CD, all those mags help get my
spectrum spread as well
samplers - was good decade for samplers - i buy lots of samplers - samplers
plenty good - me like
VALENTINA LISITSA - all her CDs came and went, but IF your system can handle
a powerful six foot blond Russian goddess making the grand piano spasm in
orgasm, find them :)
TUBA! tuba sextet
Bergen Wind Quintet
The RCA jazz reissues by decade
Ringo - Vertical Man - "I wanna get lost in your rock'n'roll" is just a fine
couple a minutes on Earth
And Drift Away ...
Al B^}
=========================================================================
From: Raymond Koonce <rkoonce@tyler.net>
Subject: [JN] 91A
Date: Thu, 13 Sep 2001 20:24:58 -0500
Source: Sound Digest Archive v02.n969
Hi Joes, Kurt, Tom, Bob,
Here's a link to my stereo 91A clone. Take a look and tell me what you
think. http://www.tyler.net/rkoonce/red300b.html
Regards,
Raymond
=========================================================================
From: Tom =?ISO-8859-1?Q?Andr=E9?= Hansen <fishfish@yifan.net>
Subject: Re: [JN] 91A
Date: Fri, 14 Sep 2001 04:51:16 +0200
Source: Sound Digest Archive v02.n969
Wow! It looks great Raymond.
I'm ashamed of the ones I'm building. Using an old big gray/green box
(old Telefunken amp) ... hehe.
- --
Tom André Hansen
=========================================================================
From: Raymond Koonce <rkoonce@tyler.net>
Subject: Re: [JN] 91A
Date: Fri, 14 Sep 2001 09:26:17 -0500
Source: Sound Digest Archive v02.n971
Hi Robert,
Thanks, I like it:-) For the grounding scheme, I use 12 gauge copper
(the bare ground stripped from a length of Romex). I run a bar of it
across one side the motor run caps and I make a pass near the tube
sockets, bent at about a 90 degree angle towards the rear of the amp and
grounded to the chassis between the input jacks. I grind an area of the
chassis to bare metal and use a star washer and bolt to get a good
connection. Everything grounds to this wire including the mains
ground. I used a voltage divider to raise the 6SJ7 cathodes about 40V
above ground and the hum is very low, much lower even than my 2A3 amp.
Regards,
Raymond
rchamber@norwich.edu wrote:
>
> Hi Raymond-
>
> Very nice work and craft, and a very distinct esthetic! Reminds me a bit
> of the 50s hot rod shows - all that gleaming red and chrome acorn nuts!
>
> Just wondering if you could describe for us what you use for the ground
> bus, and also describe its configuration, i.e. routing and chassis and
> mains ground point(s)
>
> Regards,
>
> Robert
>
>
> Raymond Koonce
> <rkoonce@tyler To: Joe List <sound@lists.io.com>,
> .net> rg@tyler.net, Kurt Steffensen
> Sent by: <kurt-steffensen@teliamail.dk>, "Tom André
> owner-sound@li Hansen" <fishfish@yifan.net>,
> sts.io.com rblemker@mail.com
> cc:
> Subject: [JN] 91A
> 09/13/01 09:24
> PM
>
>
>
> Hi Joes, Kurt, Tom, Bob,
>
> Here's a link to my stereo 91A clone. Take a look and tell me what you
> think. http://www.tyler.net/rkoonce/red300b.html
>
> Regards,
>
> Raymond
=========================================================================
From: "Paul Croft" <pcroft@iximd.com>
Subject: RE: [JN] 91A
Date: Fri, 14 Sep 2001 12:11:00 -0400
Source: Sound Digest Archive v02.n971
Hi Raymond,
Wow, this is beautiful!
Cheers,
Paul
> -----Original Message-----
> From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
> Behalf Of Raymond Koonce
> Sent: Thursday, September 13, 2001 9:25 PM
> To: Joe List; rg@tyler.net; Kurt Steffensen; Tom André Hansen;
> rblemker@mail.com
> Subject: [JN] 91A
>
>
> Hi Joes, Kurt, Tom, Bob,
>
> Here's a link to my stereo 91A clone. Take a look and tell
> me what you
> think. http://www.tyler.net/rkoonce/red300b.html
>
> Regards,
>
> Raymond
>
=========================================================================
From: rchamber@norwich.edu
Subject: Re: [JN] 91A
Date: Fri, 14 Sep 2001 13:00:47 GMT
Source: Sound Digest Archive v02.n971
Hi Raymond-
Very nice work and craft, and a very distinct esthetic! Reminds me a bit
of the 50s hot rod shows - all that gleaming red and chrome acorn nuts!
Just wondering if you could describe for us what you use for the ground
bus, and also describe its configuration, i.e. routing and chassis and
mains ground point(s)
Regards,
Robert
Raymond Koonce
<rkoonce@tyler To: Joe List <sound@lists.io.com>,
.net> rg@tyler.net, Kurt Steffensen
Sent by: <kurt-steffensen@teliamail.dk>, "Tom André
owner-sound@li Hansen" <fishfish@yifan.net>,
sts.io.com rblemker@mail.com
cc:
Subject: [JN] 91A
09/13/01 09:24
PM
Hi Joes, Kurt, Tom, Bob,
Here's a link to my stereo 91A clone. Take a look and tell me what you
think. http://www.tyler.net/rkoonce/red300b.html
Regards,
Raymond
=========================================================================
From: "Vernon Brown" <vhbrown@mediaone.net>
Subject: RE: [JN] 91A
Date: Fri, 14 Sep 2001 15:13:14 -0400
Source: Sound Digest Archive v02.n971
Beautiful! I particularly like the way the caps are mounted by clamping
them from beneath against the bottom ridge of the cap. This must have
required very precise holes. How did you cut them?
Regards,
Sandy Brown
> -----Original Message-----
> From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
> Behalf Of Raymond Koonce
> Sent: Thursday, September 13, 2001 9:25 PM
> To: Joe List; rg@tyler.net; Kurt Steffensen; Tom Andre Hansen;
> rblemker@mail.com
> Subject: [JN] 91A
>
>
> Hi Joes, Kurt, Tom, Bob,
>
> Here's a link to my stereo 91A clone. Take a look and tell me what you
> think. http://www.tyler.net/rkoonce/red300b.html
>
> Regards,
>
> Raymond
>
>
=========================================================================
From: Raymond Koonce <rkoonce@tyler.net>
Subject: Re: [JN] Sv: 91A
Date: Fri, 14 Sep 2001 19:43:30 -0500
Source: Sound Digest Archive v02.n973
Still waiting. Hope they come soon.
Thanks for your thoughtful comments Kurt. We're really hurting here.
Regards,
Raymond
Kurt Steffensen wrote:
> > Hi Joes, Kurt, Tom, Bob,
> >
> > Here's a link to my stereo 91A clone. Take a look and tell me what you
> > think. http://www.tyler.net/rkoonce/red300b.html
>
> I think GREAT :-)
>
> Looks very cool and glinsey.
>
> Still waiting for the FullMusic 300B's ?
>
> - Kurt
=========================================================================
From: "Kurt Steffensen" <kurt-steffensen@teliamail.dk>
Subject: Sv: [JN] 91A
Date: Sat, 15 Sep 2001 01:51:04 +0200
Source: Sound Digest Archive v02.n973
Hi Tom André.
> Wow! It looks great Raymond.
>
> I'm ashamed of the ones I'm building. Using an old big gray/green box
> (old Telefunken amp) ... hehe.
You should't be..
Old Telefunken amps go for zillion Dollars at eBay.
;-)
- - Kurt
=========================================================================
From: "Kurt Steffensen" <kurt-steffensen@teliamail.dk>
Subject: [JN] Sv: 91A
Date: Sat, 15 Sep 2001 01:52:52 +0200
Source: Sound Digest Archive v02.n973
> Hi Joes, Kurt, Tom, Bob,
>
> Here's a link to my stereo 91A clone. Take a look and tell me what you
> think. http://www.tyler.net/rkoonce/red300b.html
I think GREAT :-)
Looks very cool and glinsey.
Still waiting for the FullMusic 300B's ?
- - Kurt
=========================================================================
From: Tom =?ISO-8859-1?Q?Andr=E9?= Hansen <fishfish@yifan.net>
Subject: Re: Sv: [JN] 91A
Date: Sat, 15 Sep 2001 02:38:47 +0200
Source: Sound Digest Archive v02.n973
Kurt Steffensen wrote:
>
>>You should't be..
>>Old Telefunken amps go for zillion Dollars at eBay.
>>;-)
>>
>>- Kurt
>
This one wouldn't ... not much original (or working) inside when I got
it. Not going to see the tubes glow, but it will be nice and cat safe :)
- --
Tom André Hansen
=========================================================================
From: David Barnett <d_n_b@swbell.net>
Subject: Re: [JN] 91A
Date: Sat, 15 Sep 2001 13:29:29 -0500
Source: Sound Digest Archive v02.n974
On Thu, 13 Sep 2001 20:24:58 -0500, Raymond Koonce <rkoonce@tyler.net>
wrote:
>Here's a link to my stereo 91A clone. Take a look and tell me what you
>think. http://www.tyler.net/rkoonce/red300b.html
What iron did you use?
What are the four transformers or chokes in the upper left hand corner
of the inside photo, filaments?
- --dnb
=========================================================================
From: Raymond Koonce <rkoonce@tyler.net>
Subject: Re: [JN] 91A
Date: Sat, 15 Sep 2001 14:54:37 -0500
Source: Sound Digest Archive v02.n975
Hi David,
I used all Hammond iron, the 1627SE outputs and the 278CX power transformer
(400-0-400 @ 465ma, runs very cool). I think they're reasonably priced
outstanding performers. The four transformers underneath are a 5VCT 3A for
the rectifier tube, two 5V 2A for the 300Bs and a 6.3V filament transformer
for the input tubes. There are also two 10 Hy 125mA chokes bolted to the back
of the chassis box. I switch the filaments on first, wait about a minute or
so and then switch on the high voltage. I use the reverse sequence to switch
off and let the caps drain.
Regards,
Raymond
David Barnett wrote:
> On Thu, 13 Sep 2001 20:24:58 -0500, Raymond Koonce <rkoonce@tyler.net>
> wrote:
>
> >Here's a link to my stereo 91A clone. Take a look and tell me what you
> >think. http://www.tyler.net/rkoonce/red300b.html
>
> What iron did you use?
>
> What are the four transformers or chokes in the upper left hand corner
> of the inside photo, filaments?
>
> --dnb
=========================================================================
From: "Jim Dudley" <jimd@polaris.net>
Subject: Re: [JN] 91A
Date: Sat, 15 Sep 2001 22:00:27 -0400
Source: Sound Digest Archive v02.n975
Raymond,
How did you mount the big caps on top? I've got some Aeroxvox caps with no
mtg hardware and need to do the same.
TIA,
Jim D.
=========================================================================
From: tubeman@mindless.com
Subject: [JN] 96/24 vs 44/16
Date: Sun, 11 Jul 1999 14:41:46 -0400 (EDT)
Source: Sound Digest Archive v02.n202
Telecom privatization has come to Switzerland and now I can actually afford to receive the Joenet at
home. I hope I haven't usurped somebody elses "tubeman" title (see email address). I'm really jus
t a pretender to the throne...
I read with interest the 96/24 debate and I'd like to make a few relevant points: there are GOOD rea
sons why 96/24 recordings should sound better even if you can't hear past 20kHz and your DA converte
r is noisy!
Point 1: No brick-wall filters. Before AD conversion, the input signal needs to be run through a l
ow-pass filter to get rid of signals above the sampling frequency/2.2. So for 44kHz, you need to fi
lter out everything coming from the mic feed above 20kHz or else you'll get noise in the digital sig
nal. Naturally, if you want an analog filter that cuts out everything above 20kHz, this filter is g
oing to also do things to the signal below 20kHz. By going to a 96kHz sample rate, you move out the
low-pass filtering requirement to 44kHz. It doesn't matter whether your DA converter is noisy or no
t, you'll hear that!
Point 2: Noise is ADDITIVE. This is a basic point, but I think some people are missing it. Digiti
zing an analog signal creates quantization noise. This noise is in addition to the noise of your DA
converter. Unless you've got an EXTREMELY noisy DA converter, you're going to notice the differenc
e between 24 vs 16 bits. A noisy DA converter would have noise about the same order of magnitude as
the quantization noise of a 16 bit recording. Switch from a 16 bit recording to a 24 bit recording
on this bad DA converter and you have halved the noise!
By the way, the example that someone listed about the dcs sample-rate converter was a bad example if
they were converting up from 16 bits because the quantization noise from 16 bit AD conversion is st
ill there. Even if they were converting down from 24 bits, there are still a lot of unknowns about
the truncation process (eg. noise shaping) to make any comparisons iffy.
Point 3: Digital to Analog chips are really Digital to Digital chips. DA chips take an I2S signal
and convert it to a step signal: think stairs versus ramp. These steps add a lot of noise above 20k
Hz (in the case of a 44kHz sample rate). You still need to run this step signal through an analog l
ow-pass filter to get rid of the steps. You can hear the impact of these filters below 20kHz. Over
-sampling digital filters lessen this problem by upsampling the original signal, thereby making the
step size smaller. For a 44kHz sample rate, upsampled 8 times to 264 kHz, you only need to filter o
ut the digital noise above 240kHz. However, the up-sample process creates problems of its own. The
re really is no "right" way to upsample and the better upsampling algorithms are too mathematically
intense to implement real time in a cheap upsampling chip. A 96kHz sample rate moves this problem ou
t to where your ear is not sensitive. To be fair though, I suspect that this third point i!
s the least important of the three.
I hope someone finds this interesting, John
- ----------------------------------------------------------------
Get your free email from AltaVista at http://altavista.iname.com
=========================================================================
From: Scott Grammer <tubedude@sunnetusa.net>
Subject: Re: [JN] 96/24 vs 44/16
Date: Sun, 11 Jul 1999 15:37:30 -0400
Source: Sound Digest Archive v02.n202
Jim de Kort wrote:
> (snip)
>
> If you have say a 10kHz sine with on it a superimposed 30kHz dip or peak or
> whatever which forms the tone being recorded. A 44kHz sample rate might
> just sample before or after the top of the peak. This means you will not
> get the same signal on the output as was recorder.(snip)
Right. It would end up just the same as if you had heard that signal being
perfectly reproduced through the air; Your eardrums would respond to the 10k
part of the signal, and not the 30k part.
S.G.
- --
TubeDude's Webpage of Vacuum Tube Lore! http://www.cdc.net/~tubedude/
Smoke Free Youth! http://www.cdc.net/~tubedude/smokefreeyouth.html
The Price of Privacy. http://www.cdc.net/~tubedude/privacy.html
Chaos, panic, & disorder - my work here is done.
=========================================================================
From: Jim de Kort <jim@vt52.com>
Subject: Re: [JN] 96/24 vs 44/16
Date: Sun, 11 Jul 1999 21:05:52 +0200
Source: Sound Digest Archive v02.n202
Hi,
Anyone think of this reason..
The more samples you take the better you can reproduce the recorded signal.
If you have say a 10kHz sine with on it a superimposed 30kHz dip or peak or
whatever which forms the tone being recorded. A 44kHz sample rate might
just sample before or after the top of the peak. This means you will not
get the same signal on the output as was recorder.
The higher the sample rate, the better the reproduction of the original
signal, not just the max high frequency that is able to be recreated.
I think sample rate is more important than the number of bits (between 20
and 24 anyway).
My EU0.02
Jim de Kort
jim@vt52.com
=========================================================================
From: Jim de Kort <jim@vt52.com>
Subject: Re: [JN] 96/24 vs 44/16
Date: Sun, 11 Jul 1999 21:52:32 +0200
Source: Sound Digest Archive v02.n202
Hi,
>> whatever which forms the tone being recorded. A 44kHz sample rate might
>> just sample before or after the top of the peak. This means you will not
>> get the same signal on the output as was recorder.(snip)
>Right. It would end up just the same as if you had heard that signal being
>perfectly reproduced through the air; Your eardrums would respond to the 10k
>part of the signal, and not the 30k part.
I was kinda saying the opposite. A lower sample rate can not accuratly
reproduce a signal since it is leaving a big portion of the signal away.
You take two samples which are X miliseconds apart. What happens to the
signal value in between these two points...? This si not reproduced or
recorded.
If you increase the sample rate, say to 192kHz, you will get a muh better
reproduction than by raising it from 20 to 24 bits.
Jim de Kort
jim@vt52.com
=========================================================================
From: Allen Wright <AllenVSE@compuserve.com>
Subject: Re: [JN] 96/24 vs 44/16
Date: Mon, 12 Jul 1999 06:38:40 -0400
Source: Sound Digest Archive v02.n203
Hi Ferenc,
>>> The only bottleneck is the RIAA correction because you need a balanced
output phono amp. Does anybody have a suggestion to buy or build a fully
balanced (balanced I/O) RIAA corrector? As I know Melos, BAT, Atma-Sphere
has one but I wonder if there is an actual user somewhere and what is
his/her opinion<<<
Our RTP5 or RTP3 fully balanced RIAA phono preamp that is/was originally
sold for the home market is being developed as a pro unit for EXACTLY this
purpose.
You can see several schematics at:
www.vacuumstate.com
under the "Schematics - RTP3/5" section. If you wanted to build one
yourself, we are about to supply full or partial kits, and have completed
units available to custom order. The unit will be switchable between "flat
eq" for studio mic preamp usage, NAB/CCIR eq for tape head playback for
mastering from analog tapes to digital, and RIAA eq for the job you have
mentioned.
I don't want to get too commercialized here, so please contact me privatly
for more details if you are interested.
Allen (Vacuum State electronics)
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] 96/24 vs 44/16
Date: Mon, 12 Jul 1999 08:21:34 -0400
Source: Sound Digest Archive v02.n203
tubeman@mindless.com wrote:
> Point 3: Digital to Analog chips are really Digital to Digital chips. DA chips take an I2S signa
l and convert it to a step signal: think stairs versus ramp. These steps add a lot of noise above 2
0kHz (in the case of a 44kHz sample rate). You still need to run this step signal through an analog
low-pass filter to get rid of the steps.
There are some who would disagree with this. See "Non-oversampling, Digital-filter-less DAC Concept"
by Ryohei Kusunoki at http://www.sakurasystems.com/
JL
=========================================================================
From: "Ferenc Koscso" <vektorbp@mail.datanet.hu>
Subject: Re: [JN] 96/24 vs 44/16
Date: Mon, 12 Jul 1999 10:14:46 +0200
Source: Sound Digest Archive v02.n203
> Telecom privatization has come to Switzerland and now I can actually afford
> to receive the Joenet at home. I hope I haven't usurped somebody elses
> "tubeman" title (see email address). I'm really just a pretender to the
throne...
>
> I read with interest the 96/24 debate and I'd like to make a few relevant
> points: there are GOOD reasons why 96/24 recordings should sound better
> even if you can't hear past 20kHz and your DA converter is noisy!
>
> Point 1: No brick-wall filters. Before AD conversion, the input signal
> needs to be run through a low-pass filter to get rid of signals above the
> sampling frequency/2.2. So for 44kHz, you need to filter out everything
> coming from the mic feed above 20kHz or else you'll get noise in the
> digital signal. Naturally, if you want an analog filter that cuts out
> everything above 20kHz, this filter is going to also do things to the
> signal below 20kHz. By going to a 96kHz sample rate, you move out the
> low-pass filtering requirement to 44kHz. It doesn't matter whether your DA
> converter is noisy or not, you'll hear that!
It is probably the most important! We have all the High Resolution dCS A/D,
D/A and Sample Rate Converter professional gears. We made quite a few
experiment in the past using different sampling rates (from 88.2 to 192
kHz/24 bit and DSD as well). If you do the A/D conversion 176/24 bit kHz and
then downconvert it to 44.1 kHz/16 bit, the recorded CD is much better, than
the 44.1 kHz sampled one (using the same setup and levels). The difference
is really speaks for itself. We were using a custom built DC coupled 2A3 amp
(originally JC Morrison design but modified) with KR 2A3 tube and 4 very
heavy power supply separately for all the input and output stage. The
speakers were Avantgarde Acoustics Trios with REL Stentor II subwoofers.
If you want to record (archive) your LPs digitally or making your own
recordings, for example the ultimate setup can be the following: dCS 904 A/D
- - sampled in DSD, using the Quad AES/EBU output send the signals to the
Tascam AES/EBU- TDIF converter, than TASCAM DA38 8 track tape recorder,
using all the eight tracks for the stereo DSD signal recording. In this
case you can record 2 LPs on one cheap Hi8 tape in the highest possible
mastering quality. We done that, that result is really stunning. The only
bottleneck is the RIAA correction because you need a balanced output phono
amp. Does anybody have a suggestion to buy or build a fully balanced (
balanced I/O) RIAA corrector? As I know Melos, BAT, Atma-Sphere has one but
I wonder if there is an actual user somewhere and what is his/her opinion.
Thanks for the bandwidth.
Ferenc Koscso
- --
VEKTOR SYSTEM HOUSE
>http://www.vektor.hu
BUDAPEST
Gyömröi u. 76-80.
H-1103
Hungary
T:+36 1 2621022
F:+36 1 2627083
Mobile:+36 309350606
Private Fax: +36 1 4035383
E-mail:>vektorbp@mail.datanet.hu
Mobile e-mail:>koscsof@westel900.net
=========================================================================
From: "John Hancock" <John_Hancock@swissre.com>
Subject: Re: [JN] 96/24 vs 44/16
Date: Mon, 12 Jul 1999 10:15:04 +0100
Source: Sound Digest Archive v02.n203
Jim de Kort wrote:
>> If you have say a 10kHz sine with on it a superimposed 30kHz dip or peak
or
>> whatever which forms the tone being recorded. A 44kHz sample rate might
>> just sample before or after the top of the peak. This means you will not
>> get the same signal on the output as was recorder.(snip)
Scott Grammer wrote:
>Right. It would end up just the same as if you had heard that signal being
>perfectly reproduced through the air; Your eardrums would respond to the
10k
>part of the signal, and not the 30k part.
Sorry Scott, but this is untrue. The 30kHz signal would be reflected by
the 44kHz sampling rate into a lower frequency signal (below 20kHz) and you
will hear it. This is called aliasing. Its why you have to run the analog
signal through a low-pass filter before digitizing to remove everything
above 22kHz. For practical purposes (ie perfect brick-wall filters don't
exist), you have to start filtering much lower than 22kHz--usually
significantly below 20kHz.
Everyone talks about sample rates as though Nyquist was all that matters.
There is much more to it than that. For a 44kHz sample rate, the realities
of the AD/DA process intrude into the signal well below 20kHz. A 96kHz
sample rate pushes reality farther out, where it is less offensive. With a
192kHz sample rate, you could probably avoid the anti-aliasing filter
entirely simply because most microphones aren't going to have any response
out to 96kHz. Now, I'm sure you KISS guys can appreciate the benefits of
removing a complicated filter from the signal path even if you can't hear
above 16kHz.
John
=========================================================================
From: Scott Grammer <tubedude@sunnetusa.net>
Subject: Re: [JN] 96/24 vs 44/16
Date: Mon, 12 Jul 1999 18:05:58 -0400
Source: Sound Digest Archive v02.n204
John Hancock wrote:
> Jim de Kort wrote:
> >> If you have say a 10kHz sine with on it a superimposed 30kHz dip or peak
> or
> >> whatever which forms the tone being recorded. A 44kHz sample rate might
> >> just sample before or after the top of the peak. This means you will not
> >> get the same signal on the output as was recorder.(snip)
>
> Scott Grammer wrote:
> >Right. It would end up just the same as if you had heard that signal being
> >perfectly reproduced through the air; Your eardrums would respond to the
> 10k
> >part of the signal, and not the 30k part.
>
> Sorry Scott, but this is untrue. The 30kHz signal would be reflected by
> the 44kHz sampling rate into a lower frequency signal (below 20kHz) and you
> will hear it. This is called aliasing. Its why you have to run the analog
> signal through a low-pass filter before digitizing to remove everything
> above 22kHz. For practical purposes (ie perfect brick-wall filters don't
> exist), you have to start filtering much lower than 22kHz--usually
> significantly below 20kHz.
Nah. Even first generation stuff was less than 1dB down at 20kHz. And even
cheap cd players have digital reconstruction filters that when combined with a
bit of analog filtering are only 0.1dB down at 20kHz, but better than 100dB
down at 22.05kHz.
Oversampling lets you run the anti-aliasing filter way up away from the audio
band. Please note that oversampling does not mean a higher recorded sample
rate! It just means that the a/d or d/a in question runs at a multiple of the
recorded sample rate, allowing the anti-aliasing filter (in the case of an a/d
convertor) or reconstruction filter (in the case of a d/a convertor) to be
relocated well outside the audio range to prevent ringing and ripples in the
bandpass range.
Say you ran your a/d convertor at 176.4kHz. You could begin your anti-aliasing
filter at 81kHz instead of 20.25kHz. Then, you just throw away three out of
every four samples, record the ones that are left, and voila, 44.1kHz! During
playback you can run you d/a clock at 176.4kHz, and send each sample from the
buffer memory (the RAM that sits between the transport and the d/a) four times.
You then can run your reconstruction filter at 81kHz and keep it well away from
the audio.
Guys, this is all old hat nowadays, and it all hit the market around 1986, when
the first of the "second generation" players were introduced.
> (snip)
I am moving my websites presently, and there exists on them an explanation of
all thisin detail. When Ihave them moved to the new server, I'll post the URL.
Cheers!
S.G.
- --
TubeDude's Webpage of Vacuum Tube Lore! http://www.cdc.net/~tubedude/
Smoke Free Youth! http://www.cdc.net/~tubedude/smokefreeyouth.html
The Price of Privacy. http://www.cdc.net/~tubedude/privacy.html
Chaos, panic, & disorder - my work here is done.
=========================================================================
From: "John Hancock" <John_Hancock@swissre.com>
Subject: Re: [JN] 96/24 vs 44/16
Date: Tue, 13 Jul 1999 13:06:23 +0100
Source: Sound Digest Archive v02.n204
Scott Grammer wrote:
>Oversampling lets you run the anti-aliasing filter way up away from the
audio
>band. Please note that oversampling does not mean a higher recorded sample
>rate! It just means that the a/d or d/a in question runs at a multiple of
the
>recorded sample rate, allowing the anti-aliasing filter (in the case of an
a/d
>convertor) or reconstruction filter (in the case of a d/a convertor) to be
>relocated well outside the audio range to prevent ringing and ripples in
the
>bandpass range.
>Say you ran your a/d convertor at 176.4kHz. You could begin your
anti-aliasing
>filter at 81kHz instead of 20.25kHz. Then, you just throw away three out
of
>every four samples, record the ones that are left, and voila, 44.1kHz!
During
>playback you can run you d/a clock at 176.4kHz, and send each sample from
the
>buffer memory (the RAM that sits between the transport and the d/a) four
times.
>You then can run your reconstruction filter at 81kHz and keep it well away
from
>the audio.
My apologies for the lack of diplomacy, but this is also untrue. If you
did what you describe during the AD process, you would still get aliasing.
Before you downsample to 44kHz, you still have to filter out everything
above 22kHz. The benefit of sampling at 176kHz and then downsampling to
44kHz is that you can do the filtering in the digital domain. And by the
way, have you ever looked at the impulse response of some of these
brick-door filters? It's not pretty. And another thing to keep in mind is
that with digital filters, simply saying X dB down doesn't tell the whole
picture. These filters generally add ripple to the frequency response (I'm
talking about frequency-domain ripple, not time-domain ripple) throughout
the whole spectrum:DC to 20kHz.
Second point: what you describe as upsampling, ie repeating the same value
a multiple of times, is not oversampling. Mathematically, it is exactly
equivalent to the original signal. Oversampling filters use various
interpolation algorithms to increase the number of samples--they don't just
repeat the original sample.
>Guys, this is all old hat nowadays, and it all hit the market around 1986,
when
>the first of the "second generation" players were introduced.
This is definitely not old hat. Go over to comp.dsp some time and count
the number of threads on interpolation/decimation. Like with tubes, there
is no single right way to do anything in DSP and what you can do is subject
to real-world constraints.
Again, I hope someone finds this interesting, John
=========================================================================
From: Simmonds Mathews <mathews@txc.com>
Subject: [JN] Re: 96/24 vs 44/16
Date: Tue, 13 Jul 1999 14:37:10 -0400
Source: Sound Digest Archive v02.n204
> ..........
>
> If you want to record (archive) your LPs digitally or making your own
> recordings, for example the ultimate setup can be the following: dCS 904 A/D
> - - sampled in DSD, using the Quad AES/EBU output send the signals to the
> Tascam AES/EBU- TDIF converter, than TASCAM DA38 8 track tape recorder,
> using all the eight tracks for the stereo DSD signal recording. In this
> case you can record 2 LPs on one cheap Hi8 tape in the highest possible
> mastering quality. .......
>
> Ferenc Koscso
>
What do you think of archiving on the TASCAM DA-45HR, a 24 bit (as claimed in the lit.)
DAT ?
Simmonds Mathews
=========================================================================
From: "John Hancock" <John_Hancock@swissre.com>
Subject: Re: [JN] 96/24 vs 44/16
Date: Tue, 13 Jul 1999 13:06:23 +0100
Source: Sound Digest Archive v02.n208
Scott Grammer wrote:
>Oversampling lets you run the anti-aliasing filter way up away from the
audio
>band. Please note that oversampling does not mean a higher recorded sample
>rate! It just means that the a/d or d/a in question runs at a multiple of
the
>recorded sample rate, allowing the anti-aliasing filter (in the case of an
a/d
>convertor) or reconstruction filter (in the case of a d/a convertor) to be
>relocated well outside the audio range to prevent ringing and ripples in
the
>bandpass range.
>Say you ran your a/d convertor at 176.4kHz. You could begin your
anti-aliasing
>filter at 81kHz instead of 20.25kHz. Then, you just throw away three out
of
>every four samples, record the ones that are left, and voila, 44.1kHz!
During
>playback you can run you d/a clock at 176.4kHz, and send each sample from
the
>buffer memory (the RAM that sits between the transport and the d/a) four
times.
>You then can run your reconstruction filter at 81kHz and keep it well away
from
>the audio.
My apologies for the lack of diplomacy, but this is also untrue. If you
did what you describe during the AD process, you would still get aliasing.
Before you downsample to 44kHz, you still have to filter out everything
above 22kHz. The benefit of sampling at 176kHz and then downsampling to
44kHz is that you can do the filtering in the digital domain. And by the
way, have you ever looked at the impulse response of some of these
brick-door filters? It's not pretty. And another thing to keep in mind is
that with digital filters, simply saying X dB down doesn't tell the whole
picture. These filters generally add ripple to the frequency response (I'm
talking about frequency-domain ripple, not time-domain ripple) throughout
the whole spectrum:DC to 20kHz.
Second point: what you describe as upsampling, ie repeating the same value
a multiple of times, is not oversampling. Mathematically, it is exactly
equivalent to the original signal. Oversampling filters use various
interpolation algorithms to increase the number of samples--they don't just
repeat the original sample.
>Guys, this is all old hat nowadays, and it all hit the market around 1986,
when
>the first of the "second generation" players were introduced.
This is definitely not old hat. Go over to comp.dsp some time and count
the number of threads on interpolation/decimation. Like with tubes, there
is no single right way to do anything in DSP and what you can do is subject
to real-world constraints.
Again, I hope someone finds this interesting, John
=========================================================================
From: Christian Rintelen <rintelen@datacomm.ch>
Subject: [JN] 9pin 6sn7?
Date: Mon, 29 Nov 1999 10:40:28 +0100
Source: Sound Digest Archive v02.n347
Some kind Joe recently posted the 6sn7's 9 pin equivalent. What was it
again (I lost the post)?
TIA, Christian
=========================================================================
From: Christian Rintelen <rintelen@datacomm.ch>
Subject: Re: [JN] 9pin 6sn7?
Date: Mon, 29 Nov 1999 16:25:30 +0100
Source: Sound Digest Archive v02.n347
Thanks to all Joes that responded (6cg7 and 6fq7)!
Christian
Tim Reese