Zero Distortion: Tango Time
- Thread starter bonzo75
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Even worst, they can read the specification sheets and find that there is a servo in the turntable motor.
Surely. But fortunately most manufacturers are more clever than that.
People who are worried about feedback and use turntables using an AC motor driven directly by the mains should consider that unless their amplifiers are class A they can have terrible feedback in their systems - transients will affect mains voltage that will instantaneously change motor torque ...
David,
Thanks , I never considered that absolute accuracy to .01 % is an important matter. I am just addressing technical aspects of feedback and its correlation with subjective sound. The same reasoning you apply to feedback could be applied to driving synchronous motors with three phase supplies or a de-phasing capacitor using a single phase : considering that one of them is the wrong way of doing things just because we prefer one of them.
Any way can you address my question concerning if "the negative effects of feedback loops and servo controllers are easily demonstrable and audible" in capstan tape machines?
I can't answer that Francisco, never ran any tests with tape decks and been decades since I had R2R at home. Just remember that the cheap Japanese ones were advertised with Quartz control or something to that effect.
david
Surely. But fortunately most manufacturers are more clever than that.
People who are worried about feedback and use turntables using an AC motor driven directly by the mains should consider that unless their amplifiers are class A they can have terrible feedback in their systems - transients will affect mains voltage that will instantaneously change motor torque ...
You forget about the magical power cords to smooth out any motor related issues
!david
In fact top reel machines such as the Studer A80, the A820 or the Ampex ATR 102 have servo-controlled, direct-drive-capstan tape transports. My Studer A80 using a few Tapeproject master tapes is still my analog reference for ears and brain calibration.
My point is that usually we have good and poor implementations of techniques, but we should avoid diabolization of concepts. Twenty years ago many people were against using digital circuits with DACs to build wave synthetizers to drive AC motors in turntables - probably because of experience wih poor designs, that could radiate high amounts of RF noise through power cables and the motor. Today we see manufacturers and modifiers using these same digital techniques to drive three phase motors of high quality turntables with great success.
In fact top reel machines such as the Studer A80, the A820 or the Ampex ATR 102 have servo-controlled, direct-drive-capstan tape transports. My Studer A80 using a few Tapeproject master tapes is still my analog reference for ears and brain calibration.
My point is that usually we have good and poor implementations of techniques, but we should avoid diabolization of concepts. Twenty years ago many people were against using digital circuits with DACs to build wave synthetizers to drive AC motors in turntables - probably because of experience wih poor designs, that could radiate high amounts of RF noise through power cables and the motor. Today we see manufacturers and modifiers using these same digital techniques to drive three phase motors of high quality turntables with great success.
Which TTs use this technique?
In fact top reel machines such as the Studer A80, the A820 or the Ampex ATR 102 have servo-controlled, direct-drive-capstan tape transports. My Studer A80 using a few Tapeproject master tapes is still my analog reference for ears and brain calibration.
My point is that usually we have good and poor implementations of techniques, but we should avoid diabolization of concepts. Twenty years ago many people were against using digital circuits with DACs to build wave synthetizers to drive AC motors in turntables - probably because of experience wih poor designs, that could radiate high amounts of RF noise through power cables and the motor. Today we see manufacturers and modifiers using these same digital techniques to drive three phase motors of high quality turntables with great success.
i guess the real question is whether reality is the reference? or the source? do the drives on platters for cutting heads on lathe's have speed controls? my (admittedly minimal) understanding is that they are all direct drive. with servo's.
so if the master recorders, and the lathe's, are both servo controlled, how does a tt not using a servo somehow stay pure? does it fix the problem? or is there not a problem?
and.....maybe......it's all execution.
just say'n.
i got no answers.
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FYI
I did it in DIY
I used (& other EMT lovers) this technique on my very old lady EMT930 (mono) with the famous AC three phase motor.
Eliminate the motor "resistor& capa" & connect "MITSUBISHI Inverter type FR-S520S" (input 1 phase & output three phases) with Mitsubishi "RF noise filter".
... it was a musical succes ....
Significant less motor vibrations, RPM tuning & constant, no mechanical brake-felt .....
Karel
(foto: EMT930/Mitsubishi FR/Pultec10 RIAA (disconnect EMT RIAA mono)
You can power multiple pole motors that are AC from a power amp with transformers on output, and a sine wave generator (multi channel with different phase rotation outputs). There is no speed feedback that way, as the amps feedback is purely to stop it from exploding - it maintains whatever frequency you want and won’t adjust for speed. The benefit is that you have perfectly available current and shaped sine waves. What you get from the wall varies a lot, and motor phase shift caps are pretty weak (increasing size doesn’t help).
If you’re using a single pole motor like Lenco, you can just get a regenerator that puts out a pure 50/60hz. There’s a company that makes one that was showing at RMAF. (Sadly I didn’t see a 100v version)
Carolus, how do you change phase on that FR-S520S? I don’t see the option in manual but maybe they have confusing way to say it? The device is obviously based on switching tech, so still a bit noisy.
If you’re using a single pole motor like Lenco, you can just get a regenerator that puts out a pure 50/60hz. There’s a company that makes one that was showing at RMAF. (Sadly I didn’t see a 100v version)
Carolus, how do you change phase on that FR-S520S? I don’t see the option in manual but maybe they have confusing way to say it? The device is obviously based on switching tech, so still a bit noisy.
In fact top reel machines such as the Studer A80, the A820 or the Ampex ATR 102 have servo-controlled, direct-drive-capstan tape transports. My Studer A80 using a few Tapeproject master tapes is still my analog reference for ears and brain calibration.
My point is that usually we have good and poor implementations of techniques, but we should avoid diabolization of concepts. Twenty years ago many people were against using digital circuits with DACs to build wave synthetizers to drive AC motors in turntables - probably because of experience wih poor designs, that could radiate high amounts of RF noise through power cables and the motor. Today we see manufacturers and modifiers using these same digital techniques to drive three phase motors of high quality turntables with great success.
My point was that with turntables even the best implementation of a feedback loop still has negative sonic impact.
What's the relevance of tape machines here? There's nothing in common between magnetic tape and the vinyl lp, what is it that you're comparing here?
david
Depending on the machine you'll find various types of direct drive turntables used with cutting heads, some use AC synchronous motors with no servo or feedback loop, ie shaft or idler drive and some places use direct drive Technics turntables. We know that not all masters are equal, plenty of bad ones out there and not having ever cut any lacquer myself I can't tell you if there's a negative impact from a servo driven turntable or not, but I do know that conditions for successful playback are quite different from cutting masters in fact mechanically they're inverse. This is why I never bought into the phony parallel tracking tonearms being closer to cutting heads argument.
david
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It's easy:
See "FR-S500 Instruction manual (basic)" page 8, motor three phase connections are "U-V-W" ....
With a first test run/rotation you can change two motor wiring phases & ipso facto the motor rotation.
With the appropriate RF-filter I had no issues about audible noise ......
It's music ... I like it.
I am thinking the same. Needle gliding uneven groove and smooth tape passing tape head is a different means of reading signal. Talking tape suppose to shut you up and not argue about its sq using feedback David. Because tape for us all audiophiles should be taken for granted even without listening as the ultimate in sound and the mother of all sound reproduction...hehe.
Tang
Not at all the same thing Francisco and you know it too
! You're faking here and deflecting with the tape machine examples.david
There is a lot in common - both media move a physical support at a speed that should be as regular as possible - any deviation will modulate the signal. If servos systematically introduce "nasty" variations in speed they would easily show and be listenable in tape.
Curiously tape drive has been fully studied in great depth by professionals and scientists that published and released valuable information, but vinyl is still in the phase where knowledge is mostly empirical or manufacturer property.
I am thinking the same. Needle gliding uneven groove and smooth tape passing tape head is a different means of reading signal. Talking tape suppose to shut you up and not argue about its sq using feedback David. Because tape for us all audiophiles should be taken for granted even without listening as the ultimate in sound and the mother of all sound reproduction...hehe.
Tang
Interesting - are you are considering that stylus drag reacts with the servo action? Although one of the processes is magnetic and the other electromechanical the only thing that distinguishes them in terms of mechanical interaction is vinyl friction.
Tape is considered an analog reference by most audiophiles as it is at the origin of the LP - unless we consider direct cut LPs.
Um, no.
I’ve never heard tape sound good before. I’m not saying it couldn’t, but no one has ever hit the play button and I was blown away. But I’ve only heard it a handful of times. And I am aware of the problem that some tapes don’t have the correct EQ settings so they’ll probably never sound “right” for many of us - the settings are long lost.
Why has it never sounded good? I don’t know that answer. I have no idea if it’s a mix of silly hackery done to some machines, the stereo being played on, or what.
I’ve never heard tape sound good before. I’m not saying it couldn’t, but no one has ever hit the play button and I was blown away. But I’ve only heard it a handful of times. And I am aware of the problem that some tapes don’t have the correct EQ settings so they’ll probably never sound “right” for many of us - the settings are long lost.
Why has it never sounded good? I don’t know that answer. I have no idea if it’s a mix of silly hackery done to some machines, the stereo being played on, or what.
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