Aren't you exaggerating a bit?
PIM?
Hi Klaus and Pavel,
Your sims are quite interesting, but I'm not sure how to interpret the results. Are the ZC shifts a result of phase modulation or something else, a DC level shift, for example. To figure that out, you must look at the rising and falling ZC as well. As these shifts may be rather subtle, round-off errors of the simulator might compromise the results, in particular if they are based on only one or two points.
Therefore I prefer to make use of FFT's in order to calculate the phase shift more accuratly. As a FFT uses at least 1024 points, it's quite obvious that this method (due to averaging) is far less prone to round-off errors.
@Pavel
If time allows, just try: Y= phase(fft(v(out))) - phase(fft(v(in))) and narrow the X range by something like F+1e-12, F-1e-12.
Else, perhaps you can send me the *.CIR file for the 5532 (as used in post #6407) and I will run that sim.
Cheers,
Edmond.
Hi Klaus and Pavel,
Your sims are quite interesting, but I'm not sure how to interpret the results. Are the ZC shifts a result of phase modulation or something else, a DC level shift, for example. To figure that out, you must look at the rising and falling ZC as well. As these shifts may be rather subtle, round-off errors of the simulator might compromise the results, in particular if they are based on only one or two points.
Therefore I prefer to make use of FFT's in order to calculate the phase shift more accuratly. As a FFT uses at least 1024 points, it's quite obvious that this method (due to averaging) is far less prone to round-off errors.
@Pavel
If time allows, just try: Y= phase(fft(v(out))) - phase(fft(v(in))) and narrow the X range by something like F+1e-12, F-1e-12.
Else, perhaps you can send me the *.CIR file for the 5532 (as used in post #6407) and I will run that sim.
Cheers,
Edmond.
>Which is why tube amps and turntables work. Both have extremely low inter-channel phasing issues. Totally analog. Taken to another point of analysis, it shows why digital amps are generally considered...to the more learned ear...to 'suck'.<
KBK - If you actually look at the interchannel phase issues with a cantilever bouncing around a warped record I'm sure you will swamp the femto-seconds that everyone is throwing around.
KBK - If you actually look at the interchannel phase issues with a cantilever bouncing around a warped record I'm sure you will swamp the femto-seconds that everyone is throwing around.
Re: PIM?
@Pavel
If you are using the 5532/5534 model below don't bother to simulate distortions or any other time domain stuff. This macromodel (originating from TI) is garbage for anything but DC and AC analysis. It's essentially a diff stage with degeneration and resistive loads, biased by an ideal current source, followed by synthetic (POLY) gain and output stages. It also uses internally the 0 ground node
Compare this model with the internal schematic in the original Philips datasheet http://www.datasheetcatalog.org/datasheet/philips/NE5533A.pdf
BTW, you need to add a 22.5pF cap between model pins 6 and 7 to emulate a compensated NE5532.
If you have a validated 5532/5534 device level model, I would be interested myself.
.SUBCKT NE5534 1 2 3 4 5 6 7
*
C1 11 12 7.703E-12
DC 5 53 DX
DE 54 5 DX
DLP 90 91 DX
DLN 92 90 DX
DP 4 3 DX
EGND 99 0 POLY(2) (3,0) (4,0) 0 .5 .5
FB 7 99 POLY(5) VB VC VE VLP VLN 0 2.893E6 -3E6 3E6 3E6 -3E6
GA 6 0 11 12 1.382E-3
GCM 0 6 10 99 13.82E-9
IEE 10 4 DC 133.0E-6
HLIM 90 0 VLIM 1K
Q1 11 2 13 QX
Q2 12 1 14 QX
R2 6 9 100.0E3
RC1 3 11 723.3
RC2 3 12 723.3
RE1 13 10 329
RE2 14 10 329
REE 10 99 1.504E6
RO1 8 5 50
RO2 7 99 25
RP 3 4 7.757E3
VB 9 0 DC 0
VC 3 53 DC 2.700
VE 54 4 DC 2.700
VLIM 7 8 DC 0
VLP 91 0 DC 38
VLN 0 92 DC 38
.MODEL DX D(IS=800.0E-18)
.MODEL QX NPN(IS=800.0E-18 BF=132)
.ENDS
Edmond Stuart said:
@Pavel
If you are using the 5532/5534 model below don't bother to simulate distortions or any other time domain stuff. This macromodel (originating from TI) is garbage for anything but DC and AC analysis. It's essentially a diff stage with degeneration and resistive loads, biased by an ideal current source, followed by synthetic (POLY) gain and output stages. It also uses internally the 0 ground node
Compare this model with the internal schematic in the original Philips datasheet http://www.datasheetcatalog.org/datasheet/philips/NE5533A.pdfBTW, you need to add a 22.5pF cap between model pins 6 and 7 to emulate a compensated NE5532.
If you have a validated 5532/5534 device level model, I would be interested myself.
.SUBCKT NE5534 1 2 3 4 5 6 7
*
C1 11 12 7.703E-12
DC 5 53 DX
DE 54 5 DX
DLP 90 91 DX
DLN 92 90 DX
DP 4 3 DX
EGND 99 0 POLY(2) (3,0) (4,0) 0 .5 .5
FB 7 99 POLY(5) VB VC VE VLP VLN 0 2.893E6 -3E6 3E6 3E6 -3E6
GA 6 0 11 12 1.382E-3
GCM 0 6 10 99 13.82E-9
IEE 10 4 DC 133.0E-6
HLIM 90 0 VLIM 1K
Q1 11 2 13 QX
Q2 12 1 14 QX
R2 6 9 100.0E3
RC1 3 11 723.3
RC2 3 12 723.3
RE1 13 10 329
RE2 14 10 329
REE 10 99 1.504E6
RO1 8 5 50
RO2 7 99 25
RP 3 4 7.757E3
VB 9 0 DC 0
VC 3 53 DC 2.700
VE 54 4 DC 2.700
VLIM 7 8 DC 0
VLP 91 0 DC 38
VLN 0 92 DC 38
.MODEL DX D(IS=800.0E-18)
.MODEL QX NPN(IS=800.0E-18 BF=132)
.ENDS
scott wurcer said:
Thanks, Scott.
It's sad that some here don't understand that those who measure and apply science also listen, are intensely interested in understanding why components sound the way they do, and do allow for the possibility that there are things we do not yet understand.
Cheers,
Bob
Re: PIM?
I think I sorted out this type of problems (had the same suspicions). See attached test circuit. Enough testpoints (even in the zoomed area more than 1 per pixel), enough precision (LTspice can do double precision, ".option numdgt=15").
The circuit produces only expanding 3rd harmonic of a 4kHz sine, in high amounts with higher levels. There is no DC offset, and the signal is perfectly symmetric. That signal is fed into the allpass (RC-LP @ 10kHz), which has significantly different group delay shift at the 3rd at 12kHz. The left-shifted (in time, about 60deg) 3rd is very visible, yielding those ZC shifts because its level increases.
Still in the FFT data all steps yield exactly the same results of phase relationships between fundamental and harmonic (and between output and generator), regardless of level, as is the THD data of allpass out vs generator.
So my conclusion from observing such ZC shifts, provided that trivial error sources are absent (DC, even order stuff etc, which is hard to achieve in practise), is not necessarily that there is true phase distortion (signal dependent phase changes). When there is phase shift actually coming from things like shifted pole frequencies from non-linear caps, these seem to add/subtract to the basic effect, making it hard to identify or correlate these ZC shift graphs to anything meaningful. That my 2cts only...
- Klaus
Hi Edmond,Edmond Stuart said:
I think I sorted out this type of problems (had the same suspicions). See attached test circuit. Enough testpoints (even in the zoomed area more than 1 per pixel), enough precision (LTspice can do double precision, ".option numdgt=15").
The circuit produces only expanding 3rd harmonic of a 4kHz sine, in high amounts with higher levels. There is no DC offset, and the signal is perfectly symmetric. That signal is fed into the allpass (RC-LP @ 10kHz), which has significantly different group delay shift at the 3rd at 12kHz. The left-shifted (in time, about 60deg) 3rd is very visible, yielding those ZC shifts because its level increases.
Still in the FFT data all steps yield exactly the same results of phase relationships between fundamental and harmonic (and between output and generator), regardless of level, as is the THD data of allpass out vs generator.
So my conclusion from observing such ZC shifts, provided that trivial error sources are absent (DC, even order stuff etc, which is hard to achieve in practise), is not necessarily that there is true phase distortion (signal dependent phase changes). When there is phase shift actually coming from things like shifted pole frequencies from non-linear caps, these seem to add/subtract to the basic effect, making it hard to identify or correlate these ZC shift graphs to anything meaningful. That my 2cts only...
- Klaus
Attachments
Hi Klaus,
Thanks for input. I'm glad you came to the same conclusion. This also explains why I got a complete different outcome when a I looked at the true phase modulation (only femtoseconds)
Only one remark about the number of data points. I didn't mean the number of points available, rather used for calculation. So in case of looking only at the ZC, this is just one data point. That my 1ct only...
Cheers,
Edmond.
Thanks for input. I'm glad you came to the same conclusion. This also explains why I got a complete different outcome when a I looked at the true phase modulation (only femtoseconds)
Only one remark about the number of data points. I didn't mean the number of points available, rather used for calculation. So in case of looking only at the ZC, this is just one data point. That my 1ct only...
Cheers,
Edmond.
John, again I don't understand what you are saying. Bob referenced Barrie's work and pointed out that they don't disagree. All these works are available for free and people can read them and make up their own minds. Fundamental new insights are NOT being made here.
There is absolutely nothing to dislike about Barrie at one point even I think he was using zero feedback amplifiers.
There is absolutely nothing to dislike about Barrie at one point even I think he was using zero feedback amplifiers.
I have made up MY mind, and I won't comment about Cordell's work, since I have not tried to duplicate a 'dud' test and in professional fairness (unlike many here) will not pick it apart, before I do. I will just suspend judgement on his measurements, like I do ABX testing.
PMA is on the right track, showing, even if exaggerated, what PIM should do. Of course, it HAS to 'stand out' or everyone would ignore it, as usual. Keep up the good work, PMA.
PMA is on the right track, showing, even if exaggerated, what PIM should do. Of course, it HAS to 'stand out' or everyone would ignore it, as usual. Keep up the good work, PMA.
john curl said:
John,
Despite your protests otherwise, Barrie Gilbert's work does NOT support your argument. You are just trying to ride the coat tails of his brilliance. You are name-dropping to try to support your position. I believe in Barrie Gilbert and I like Barrie Gilbert. His work does not disagree with what I wrote 20 years prior.
Bob
Since I 'NAIL' you (and Scott) on just about everything, you should not 'guess' as to what I read or understand. Barrie Gilbert is no friend of mine, but he makes a strong mathematical point and prediction that PMA is finding in his simulations.
What do you mean that SPICE models are not virtually perfect? That is what you told me, in the past.
Bob Cordell, please remember our 16 page REBUTTAL to you and your modification of technical reality to suit your needs and ego, back in 1980. We did not invest the time and effort in TIM for 10 years to have some upstart tell us where the bear sits, when he did not know, himself. And you still have far to go, in my opinion.
We have not formally rebutted you yet in regards to PIM, but it will come, I am fairly sure.
Now, why don't you leave us alone to research PIM in our own way? Why bother PMA, me, or anyone else interested in it? This is the 'Blowtorch' thread, not one of your numerous other theads here, why do you come here to insult us? Are we getting close to something important?
What do you mean that SPICE models are not virtually perfect? That is what you told me, in the past.
Bob Cordell, please remember our 16 page REBUTTAL to you and your modification of technical reality to suit your needs and ego, back in 1980. We did not invest the time and effort in TIM for 10 years to have some upstart tell us where the bear sits, when he did not know, himself. And you still have far to go, in my opinion.
We have not formally rebutted you yet in regards to PIM, but it will come, I am fairly sure.
Now, why don't you leave us alone to research PIM in our own way? Why bother PMA, me, or anyone else interested in it? This is the 'Blowtorch' thread, not one of your numerous other theads here, why do you come here to insult us? Are we getting close to something important?
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