** John. Phono preamps have no eyes. They see even less than you
They have no shocks. Please stop waffling.jan didden
Jan, think of my efforts to improve the phono system as a better way to handle potholes and speed bumps in an automobile. Automobile suspensions were an early design problem that took analog computers (with op amps) to emulate. This is how I think about the '2 stage' solution. At this very moment, I have an all IC phono stage in review at 'Stereophile'. And you talk to me about my avoiding IC op amps! Well, my $40,000 preamp is all discrete! ;-) Same basic topology as the IC version.
PMA said:
Yeah, I'm not a professional. However a preamp I built several years back sent two preamps that achieved a class A rating in Stereophile packing. My dad loves nothing better than to tell me how much better his audiophile gear sounds than the stuff I build. But, he couldn't this time.
Yes I've built IC ( high speed video buffer ) based preamps that got displaced by my dad's audiophile gear. But, my discrete no global feedback preamp saved the day.
So, I'm kind of anti-op-amp or pro good overtones ... can't decide which yet. Maybe both.
Johnl, I appreciate your input, in any case. I could care less whether an op amp can be made that is almost perfect. I haven't found it yet, but I am still looking. Perhaps, the ADI op amp championed by Pavel will do the job. I HOPE SO, because I will change over to it immediately, if it does the trick. However, I will STILL use a 2 stage design. It just has too many advantages over a single OP AMP with RIAA compensation, that I used with the Levinson JC-2. Please note that the output stage is STILL weak, and has to be buffered. NOT GOOD.
Quote >
The exact schematic is essentially useless except to experts.
I do not intend to argue with amateurs.
This does not cut it for me you just lost quite a bit of points.
John Curl put in the challenge
5KHz on a phono stage with signal a full output.
Picture and what not of the real thing welcome.
(who be the first to post?)
I was given the impression that this tread is the follow up
For the Blowtorch Preamplifier
You would agree with me that under the spaghetti you could see a couple of IC
So what’s the argument about OP amps are baad?
I got no problems with OP amps or Solid State or Lumpa Lumpas
As long as the job get done who is to care.
I would like to see more of the first 100 pages of the Babble fish tread and same more of the circuit.
And if some one can do better please do post.
Al
The exact schematic is essentially useless except to experts.
I do not intend to argue with amateurs.
This does not cut it for me you just lost quite a bit of points.
John Curl put in the challenge
5KHz on a phono stage with signal a full output.
Picture and what not of the real thing welcome.
(who be the first to post?)
I was given the impression that this tread is the follow up
For the Blowtorch Preamplifier
You would agree with me that under the spaghetti you could see a couple of IC
So what’s the argument about OP amps are baad?
I got no problems with OP amps or Solid State or Lumpa Lumpas
As long as the job get done who is to care.
I would like to see more of the first 100 pages of the Babble fish tread and same more of the circuit.
And if some one can do better please do post.
Al
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Are you trying to show me something, Pavel, or did you not understand that an RC time constant AFTER the op amp output would continue the curve? Also, WHY should you NOT stop the drop? The added phase shift would HELP the phono response. Your response is only off 3dB or so at 200KHz. Why not stop it at 50KHz? Some do.
Pavel, let's get back to your inverting integrator. You still have not told me which type you are using. However, let me warn you in advance, that either integrator approach will pre-filter the input transient to be the same as the output. Unfortunately, a phono stage, in general, will NOT pre-filter the transient.
Belated Holiday response
Hi Jan,
PMA’s original post stated that vinyl distorts horribly with an implication about being able to listen around them. It just took me by surprise as my experience with vinyl doesn't find its issues that dramatic. I was curious about his front end electronics and tried to leave the well known cartridge, arm, TT issues out of it.
PMA's response was that the electronic were not the issue. My response to this was obviously not clear as to what I was getting at as I thought.
To answer your question first:
I'm not suggesting that the electronics should modify or correct for vinyl’s ills by undistorting it. Simply put, I'm suggesting that the electronics needs to present them honestly. Much the same as an amp or preamp can present a recording as fully realized, pure of tone with a sense of atmosphere and of body, while a slightly different component will somehow choke the life out of the piece leaving it a bit flat and not so pure. How a system processes the sound of vinyl’s distortions will affect ones perception of them.
I hope that is clear now. It was just a gut reaction to something thrown out that I didn't quite agree with.
Regards,
Mike
Hi Jan,
PMA’s original post stated that vinyl distorts horribly with an implication about being able to listen around them. It just took me by surprise as my experience with vinyl doesn't find its issues that dramatic. I was curious about his front end electronics and tried to leave the well known cartridge, arm, TT issues out of it.
PMA's response was that the electronic were not the issue. My response to this was obviously not clear as to what I was getting at as I thought.
To answer your question first:
I'm not suggesting that the electronics should modify or correct for vinyl’s ills by undistorting it. Simply put, I'm suggesting that the electronics needs to present them honestly. Much the same as an amp or preamp can present a recording as fully realized, pure of tone with a sense of atmosphere and of body, while a slightly different component will somehow choke the life out of the piece leaving it a bit flat and not so pure. How a system processes the sound of vinyl’s distortions will affect ones perception of them.
I hope that is clear now. It was just a gut reaction to something thrown out that I didn't quite agree with.
Regards,
Mike
John, I understand your concerns. In this particular case, I would not disclose more about the circuit. It is a professional product, that I have been selling to a demanding customer repeatedly for some 15 years. It covers 6 frequency decades and is tuned to 3 ranges, depending on lowest and highest operating frequencies required. The results over years are excellent, under conditions with very high level of EMI interference, transient input overload, etc.
The sensor that provides input signal for the integrator is very robust and low-impedance. It is highly improbable and almost impossible for the integrator to modify its output transient. The sensors + integrators are calibrated by comparative method with fast certified reference shunt and they obtain test approval finally. For several reasons, the rogowski coil + integrator method is more versatile than the shunt method.
Let me just say that if we take a GENERIC inverting integrator of either RL or RC configuration, the input pulse will be pre-filtered by the passive network, BEFORE it reaches the input stage of the op amp. Therefore, you are not performing the 'miracle' that you think you are doing with your op amp design. Of course, if you only amplified the coil's output, then you would be on to something, and I would thank you for it. However, from my position, your 'real' impulse at the input of any op amp you might have chosen is 2 times slower than my TIM(30,30) pulse although my TIM(30,30) would turn back into a risetime limited square wave, if it went into YOUR inverting integrator before it reached your op amp input, which would be quite easy for you to handle.
Why don't you try to do what you are successful at doing, with a non-inverting quasi integrator, or a typical phono stage like you showed on your graph, and see what happens?
Why don't you try to do what you are successful at doing, with a non-inverting quasi integrator, or a typical phono stage like you showed on your graph, and see what happens?
I am certainly doing no miracles, as they are impossible. We know the RC coil output (without integrator), we know the RC coil + integrator output voltage, we have both curves digitized in files and we can calculate errors. We can also compare RC coil + integrator output with certified reference. That's enough to assure required accuracy and to recognize possible errors.
I will not make the circuit with non-inverting integrator of the RIAA preamp style, as it is wrong solution for my application.
I showed the RC coil integrator for the reason to refute myths about feedback.
The input transient of the inverting integrator is NOT filtered. The output current (not voltage) of the inverting integrator, that is charging the feedback capacitor, MUST have exactly same shape as input transient voltage (before integrator input) divided by input integrator resistor value. If not, then the output integrator VOLTAGE is distorted and we are able to measure it both by numerical integration comparative method and reference shunt comparative method.
That's my closing remark to the RC coil inverting integrator topic.
I will not make the circuit with non-inverting integrator of the RIAA preamp style, as it is wrong solution for my application.
I showed the RC coil integrator for the reason to refute myths about feedback.
The input transient of the inverting integrator is NOT filtered. The output current (not voltage) of the inverting integrator, that is charging the feedback capacitor, MUST have exactly same shape as input transient voltage (before integrator input) divided by input integrator resistor value. If not, then the output integrator VOLTAGE is distorted and we are able to measure it both by numerical integration comparative method and reference shunt comparative method.
That's my closing remark to the RC coil inverting integrator topic.
Mike I see, yes that's also largely my take. Electronics cannot somehow cutout the distotion and let through the sound. Whatever the shortcomings are of vinyl, determined by the mechanical process, you'll hear them with any good preamp. Which is OK; I enjoy LPs as much as anyone.
John's analogy of a car steering around potholes is obviously wrong and might perpetuate some mythical aspects of amps that's, IMHO, misleading.
jan didden
OK let's make a summary here. We have a nice discussion about technology - especially integrators & errors - and about distortion which we measure in the 4th digit behind the comma.
I think we should come to the point which is when do I stop and bring the amplifier to a product and how does it sound! Some are stating out that they briefly heard the difference between 0.000x and 0.0000y in distortion?
How does the phono stage sound regarding the liveness of musical performance?
Once again a statement from the conductor Eliahu Inbal:
"I take seat in the taxi and a symphony was playing. Car stereo and you know it has high distortion but the liveness of the system was so gripping..."
I think we should come to the point which is when do I stop and bring the amplifier to a product and how does it sound! Some are stating out that they briefly heard the difference between 0.000x and 0.0000y in distortion?
How does the phono stage sound regarding the liveness of musical performance?
Once again a statement from the conductor Eliahu Inbal:
"I take seat in the taxi and a symphony was playing. Car stereo and you know it has high distortion but the liveness of the system was so gripping..."
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