Idlers vs Direct Drive vs Belt Drive

Audiophile Bill

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Hi End by definition is a tiny percentage of listeners to begin with and then we are talking about small percentage of products in that already minuscule market. Leaving aside how the numbers are measured and they really mean, I doubt that any of us are susceptible to an overall change change of 0.1 hz and even a bigger no. but to how and how often that adjustment is made. Its like feedback in electronics, you get some great measurements but it doesn't mean that you can't hear the effects of feedback.

david

If that were true though, how would you discern a change of speed accuracy at that level? If there is a device constantly monitoring and changing the rotational speed that prevents a TT deviating by imperceptible gradations of pitch, then you would not hear it.
 

ddk

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If that were true though, how would you discern a change of speed accuracy at that level? If there is a device constantly monitoring and changing the rotational speed that prevents a TT deviating by imperceptible gradations of pitch, then you would not hear it.

Same way we hear what feedback does to the sound. As I mentioned one time 0.1% (if its really case and not just a partial measurement) overall change or if it just off by that amount it will not be perceptible but many similar changes add up to a bigger total. What one hears and how its heard is different from person to person and system to system. Like an air conditioner that you don't hear or notice in a busy, noisy environment but you'll start hearing the blower as the environment becomes quieter as a constant and continuos noise but as things really quiet down you'll hear that the blower noise is no longer continuos, it has a discernible rhythm/pattern. Some hate it while others are totally impervious but both can agree about the cool air, of course not the temperature!

(Edit-Addition) Basically you won't notice a 0.1% inaccuracy but you'll hear when something is adjusting for that deviation in two directions, i.e. speed up, stop; slow down, stop!

david
 
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Audiophile Bill

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Same way we hear what feedback does to the sound. As I mentioned one time 0.1% (if its really case and not just a partial measurement) overall change or if it just off by that amount it will not be perceptible but many similar changes add up to a bigger total. What one hears and how its heard is different from person to person and system to system. Like an air conditioner that you don't hear or notice in a busy, noisy environment but you'll start hearing the blower as the environment becomes quieter as a constant and continuos noise but as things really quiet down you'll hear that the blower noise is no longer continuos, it has a discernible rhythm/pattern. Some hate it while others are totally impervious but both can agree about the cool air, of course not the temperature!

david

I like the analogy but I can't subscribe to it as the fluctuations even if happening on a very regular basis will still be inaudible as the pitch is not changing by perceptible margins no matter how often. If however the deviation is large enough to be perceptible, then we have an issue.
 

ddk

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I like the analogy but I can't subscribe to it as the fluctuations even if happening on a very regular basis will still be inaudible as the pitch is not changing by perceptible margins no matter how often. If however the deviation is large enough to be perceptible, then we have an issue.
If you're thinking of it as just a minute deviation of pitch as a constant, then yes no one can hear it. What you hear is the effect of mechanically speeding up then breaking, speeding up breaking, speeding up breaking, on and on and on to achieve the 0.1% number that affects the sound quality, and on many different levels not just pitch.

david
 

ddk

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Feedback reduces distortion.
Keith.

Not the point, its the way it does it and what it imposes on the sound. There's enough material out there on the audible effects of feedback, whatever the benefits. Everything is a compromise Keith you can't argue perfection in any of this, just the types and how much compromise.

david
 

ddk

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If you're thinking of it as just a minute deviation of pitch as a constant, then yes no one can hear it. What you hear is the effect of mechanically speeding up then breaking, speeding up breaking, speeding up breaking, on and on and on to achieve the 0.1% number that affects the sound quality, and on many different levels not just pitch.

david

Actually its more like speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break,speed up- break - slow down - break, speed up- break - slow down - break,speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, speed up- break - slow down - break, ….

david
 

PeterA

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Not the point, its the way it does it and what it imposes on the sound. There's enough material out there on the audible effects of feedback, whatever the benefits. Everything is a compromise Keith you can't argue perfection in any of this, just the types and how much compromise.

david

If good measurements are the goal, then perhaps the compromise is slight. If good sound is the goal, then perhaps the compromise is great. It is clear from this discussion and many others, that we are discussing individual priorities as much as anything.

I appreciate David's perspective because he seems to have both broad and deep experience with a large number of different turntables.
 

Mike Lavigne

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I think at some point you do run into speed issues on the media side of things chasing this stuff.

when I compare my Studer A-820's speed on a source tape to my DD NVS tt on the mastered from the same tape pressing, that is where the rubber hits the road. every step in the chain making and dubbing the tape, as well as mastering the pressing, all is part of the picture.

at that point we all get to have our own taste and prism to view what we hear and judge. trying to assign and count angels on the head of a pin.

no wrong and no right.

my money is on the speed of the Studer as the least compromised truth. but that's just my 2 cents. YMMV.
 

Audiophile Bill

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If you're thinking of it as just a minute deviation of pitch as a constant, then yes no one can hear it. What you hear is the effect of mechanically speeding up then breaking, speeding up breaking, speeding up breaking, on and on and on to achieve the 0.1% number that affects the sound quality, and on many different levels not just pitch.

david

What other than pitch is affected by the minute variations?
 

ddk

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I think at some point you do run into speed issues on the media side of things chasing this stuff.

when I compare my Studer A-820's speed on a source tape to my DD NVS tt on the mastered from the same tape pressing, that is where the rubber hits the road. every step in the chain making and dubbing the tape, as well as mastering the pressing, all is part of the picture.

at that point we all get to have our own taste and prism to view what we hear and judge. trying to assign and count angels on the head of a pin.

no wrong and no right.

my money is on the speed of the Studer as the least compromised truth. but that's just my 2 cents. YMMV.

At this point in time Mike even the best tt setup in the world will fall short of high end tape machines and master tapes, specifically in the "Natural" dept.! The purpose of the OP wasn't bashing one strategy in favor of another and imposing an absolute, it all comes down to each product and individual tastes, but a discussion of each one's qualities. I maintain that everything is compromised just differently, belt drive is susceptible to a variety of ills that the designer must overcome like anything else. I'm with you, at the end of the day what counts is the owner's satisfaction that counts.

david
 

ddk

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If good measurements are the goal, then perhaps the compromise is slight. If good sound is the goal, then perhaps the compromise is great. It is clear from this discussion and many others, that we are discussing individual priorities as much as anything.

I appreciate David's perspective because he seems to have both broad and deep experience with a large number of different turntables.

Measurements are deceptive Peter, we don't know what's omitted nor do we know what is our threshold of acceptance for any given type of distortion, individual and/or accumulative. Looking at some nos. in isolation is meaningless if trying to ascertain overall sound quality, measurements have their place and are necessary but they don't convey what I need as a listener. Specially in this case that every little thing counts big.

david
 

ddk

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Feedback reduces distortion, without feedback you are just adding distortion,imposing distortion on the sound.
Keith.

Are you saying that feedback is always good and has no downside?

Feedback is a type of distortion, replacing one type with another isn't the same as eliminating distortions.

david
 

ddk

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What other than pitch is affected by the minute variations?

Detail, tonal depth and harmonic contrast, sense of realism, i.e. "Natural" to name a few. To clarify all 3 different design types are susceptible to the side effects of Servo control.


david
 

PeterA

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I maintain that everything is compromised just differently, belt drive is susceptible to a variety of ills that the designer must overcome like anything else.

david

David, could you please describe the issues unique to belt drive turntables and how they can be overcome? I presume the type of belt and weight/inertia of the platter are of particular importance.

Also, I'm curious if you have any experience with the Kronos turntables. The two counterrotating platter design is unusual and I wonder if it does indeed address issues that effect other turntables while not introducing new concerns. I guess these platters could be driven with other drive types, so this question may be beyond the scope of this thread.
 

Audiophile Bill

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Detail, tonal depth and harmonic contrast, sense of realism, i.e. "Natural" to name a few. To clarify all 3 different design types are susceptible to the side effects of Servo control.


david

Thanks, David. Very interesting observations - I assumed it would only impact on pitch.
 

spiritofmusic

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I can't make any technical comment, but Vic the designer of the direct rim drive Trans Fi Salvation tt, via experimenting w/various dd Technics' and idler Garrards and Lencos, and starting w/a base belt drive Michell Gyro, found that moving away from belt was his solution to what he felt were issues that he disliked in the belt Gyro, but he didn't get on w/the sound of his intermediate stage direct rim drive w/digital servo feedback. He always felt that measuring and correcting speed led to a kind of coldness or hollowness in the sound. And this seemed to replicate what he was unhappy w/in the dd Technics. His aim was then to find a way to emulate the verve and propulsion of the classic idler Garrards and Lencos, but eliminating what he felt were their inherent weaknesses.
Only when he managed to combine a high mass platter, very high torque motor, and motor design to drain vibrations as fully as poss away from the platter/stylus interface, did he find that at a Real World price he was able to get the speed/pitch stability of the best dd's, the verve of the best idlers but eliminating traditional rumble issues.
 

Audiophile Bill

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The primary goal for a turntable design is absolute speed control,
To quote again from the GPA design paper,
It must be understood that record grooves contain only amplitude information and no frequencyinformation. The frequency information of the record is generated by the speed turned by theplayback device. Any deviations, changes or errors in the speed accuracy during playback willchange the pitch of the signal retrieved by altering its recorded frequency. Simple fact, the moreaccurately you turn the record the more accurate the frequency/pitch reproduced and hence thelower the level of distortion and the greater the level of realism. This is why we viewed superiorspeed control essential to assuring superior playback performance.




Keith.

I think we all get that Keith - this has not added to our debate here. David is saying that the regular interventions of servo can detract from the overall sound irrespective of whether it reaches an accurate absolute figure.
 

ddk

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David, could you please describe the issues unique to belt drive turntables and how they can be overcome? I presume the type of belt and weight/inertia of the platter are of particular importance.

Also, I'm curious if you have any experience with the Kronos turntables. The two counterrotating platter design is unusual and I wonder if it does indeed address issues that effect other turntables while not introducing new concerns. I guess these platters could be driven with other drive types, so this question may be beyond the scope of this thread.

Would have been easier to ask me what isn't a problem to overcome Peter than the other way around :)! All the various designs are there claiming to counteract something, better designers eliminate more and create fewer artifacts than the worse ones. Speed control is important to every design type and servo control is but one method used across the board in all 3 types with the same downsides that need to be managed. Inertia through mass and lowering of friction is another method, as is the combination. Materials, acoustic feedback, resonance, etc., etc., etc. come into play with all designs. What I can tell you is that for me and my aesthetic priorities, within the Reference groups, I've come across more successful idler & belt driven designs that DD.

In case of the Kronos the designer was tackling what he thought was important to him and the overall sq of his table, was he successful? I don't know. Has he created the best? No, but its a very fine sounding turntable with few noticeable shortcomings.

david
 

ddk

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I think we all get that Keith - this has not added to our debate here. David is saying that the regular interventions of servo can detract from the overall sound irrespective of whether it reaches an accurate absolute figure.
+1

david
 

Audiophile Bill

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The primary goal for a turntable design is absolute speed control,
To quote again from the GPA design paper,
It must be understood that record grooves contain only amplitude information and no frequencyinformation. The frequency information of the record is generated by the speed turned by theplayback device. Any deviations, changes or errors in the speed accuracy during playback willchange the pitch of the signal retrieved by altering its recorded frequency. Simple fact, the moreaccurately you turn the record the more accurate the frequency/pitch reproduced and hence thelower the level of distortion and the greater the level of realism. This is why we viewed superiorspeed control essential to assuring superior playback performance.




Keith.


I think also to reiterate my previous post it is not absolute speed accuracy that is important unless you have perfect pitch. It is wow and flutter that causes the problem.
 
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