Idlers vs Direct Drive vs Belt Drive

[rockitman]

I preferred the Caliburn for its more natural sound of a large orchestra. However the Caliburn was seating on a Hertzan RS150 active table and the AF1 on a classical stand.

Not a fair competition. The AF1 is quite off its potential not being on a Herzan TS150...sounds a lot more natural with the platform. I have been saying this for 2 years. I can't tell you how many times I come down to spin a record and say to myself something is wrong during the first cut played. Sure enough I forgot to turn the active isolation shelf ts150 on. Keep in mind the AF1 won't fit on the TS 150 by itself. It's foot print is to wide so one needs the HRS TechDas platform that has recessed feet or some other platform to fit the table on the ts150.

 

[audioblazer]

So the TT motor is not powerful enough to even take a light weight like Timeline strobe to maintain speed ?

We are digressing a bit, but...

Here's why the dot was all over the place, and why the TimeLine's weight affects speed measurement: below is a video I prepared for you of the VPI's speed accuracy (set with the KAB) playing a 1kHz test tone, and I am measuring the output frequency at the amplifier terminals. As you can see the accuracy is about 0.2% to 0.3% - hardly state of the art but definitely not all over, but keep in mind that this includes inaccuracies (e.g. speed variations) in the production chain of the LP as well, plus belt tension issues (which, BTW, is why I am replacing the rubber belt with a silk thread). However, it clearly demonstrates why the TimeLine is a "flawed testing device" as I had characterized it back then, when used JUST as such - i.e. my measurement is NOT all over the place, unlike the dot. On the other hand, the TimeLine IS a very good testing device for measuring *average* speed IF you also use it to set speed and as the exclusive center weight from that point on. So, in many ways, I am glad people didn't post videos of their experiences with the TimeLine, because I don't know whether they would suspect they would have to re-set speed with it first.

 

[ack]

So the TT motor is not powerful enough to even take a light weight like Timeline strobe to maintain speed ?

It's not lightweight, exactly the opposite, and much heavier than the VPI center weight I use, which is heavy by itself. Thus, a measuring device that affects the system under test is just a flawed measuring device; but in this case, if you also use it as your center weight, it's a fine device.

 

[Mosin]

It's not lightweight, exactly the opposite, and much heavier than the VPI center weight I use, which is heavy by itself. Thus, a measuring device that affects the system under test is just a flawed measuring device; but in this case, if you also use it as your center weight, it's a fine device.

I do not see how the Timeline can be considered a flawed device. If mass is added to the center of a rotating object, it should increase stability, not the opposite. If anything, the motor should have more control over the spin. I'm not saying the Timeline is the supreme measurement device, but it is extremely competent at the job of determining the consistency of a turntable that spins at the standard accepted speed of 33 1/3.

It is only my opinion, but maybe that particular turntable has a problem that should be checked out. Even a minor problem might cause such an inconsistency. At the very least, several turntables of that model should be sampled before a judgement is made. The Timeline dot should stay in the same place all the time with a turntable that is spinning 33 1/3, especially when the turntable in question is under a load.


*I would check it at 45 RPM to see what happens.

 

[ack]

It might increase stability, but it slows down the platter as well. When we say "all over" we mean the dot would basically move "back" rotation after rotation because of the slower speed, effectively being "all over" - we never meant that the dot would be forward one time and back the other, as if stability was affected - that was never the case. That's why I said it's a fine device if you a) re-set speed with it; b) use it as your exclusive center weight from then on.

Therefore, because it can slow down some turntables, as a testing device _alone_ it is a flawed device.

 

[Mosin]

It might increase stability, but it slows down the platter as well. When we say "all over" we mean the dot would basically move "back" rotation after rotation because of the slower speed, effectively being "all over" - we never meant that the dot would be forward one time and back the other, as if stability was affected - that was never the case. That's why I said it's a fine device if you a) re-set speed with it; b) use it as your exclusive center weight from then on.

Therefore, because it can slow down some turntables, as a testing device _alone_ it is a flawed device.

Isn't a heavy ring clamp offered as an accessory for that turntable?

...because it can slow down some turntables, as a testing device _alone_ it is a flawed device.

Assuming you are right, doesn't it then double as a measurement tool of a turntable's inertia qualities?

 

[ack]

Isn't a heavy ring clamp offered as an accessory for that turntable?

Yes, I have it too, it also slows down the platter, and speed had to be adjusted for it too; and from then on, I always use it. More than that, I can demonstrate stylus drag, so never mind the masses we are talking about...

 

[Mosin]

Yes, I have it too, it also slows down the platter, and speed had to be adjusted for it too; and from then on, I always use it. More than that, I can demonstrate stylus drag, so never mind the masses we are talking about...

It's probably a subject for another thread, but I firmly believe that stylus drag can be overcome by employing inertia in a thoughtful way.

 

[spiritofmusic]

It's probably a subject for another thread, but I firmly believe that stylus drag can be overcome by employing inertia in a thoughtful way.

I'm aware of some of your interesting thoughts on the matter, Win. Tbh, I'm very much sold on yr solution of high mass/high inertia as a method to maintain the "push" thru stylus drag, esp if the speed is not corrected on the fly all the time like the Monaco, but maybe altered only if necessary at greater spaced intervals, to avoid the "hunt and correct" principle common to the lighter platter/lower inertia principle of gear like the GP Monaco.
From what I gather, the quality of your bearing, uber massy platter and powerful motor, w/SOTA idler braking tech, may be the only high end alternative that I would consider over my very low priced, but superbly performing, Salvation direct rim drive tt.

 

[Billy Shears]

Get a acrilyc strobe disc, get a toothpic, put the strobedisc onto the high mass spinning platter, look at the speed, lower the toothpic slightly onto the stobe disc and be prepared for a shock.

My platter weighs 13 Kg and can be slowed down without a problem by stylus drag....

 

[FrantzM]

Get a acrilyc strobe disc, get a toothpic, put the strobedisc onto the high mass spinning platter, look at the speed, lower the toothpic slightly onto the stobe disc and be prepared for a shock.

My platter weighs 13 Kg and can be slowed down without a problem by stylus drag....

Here is the interesting thing: you try the same with a Technics SP 10 ... It won't slow down... Heck! You would apply a record brush...

 

[ack]

It's probably a subject for another thread, but I firmly believe that stylus drag can be overcome by employing inertia in a thoughtful way.

You are probably right, though as Bill Shears subsequently said, he observes stylus drag even with his 13kg platter and I believe it. I stayed up late last night and did a couple of experiments...

First, re-check speed with the KAB strobe paper on top of an LP, with the stylus in the grooves, all weights on as well. Then, played the same 20-minute Mahler 2nd opening piece concurrently both on CD and LP, after time-aligning them to within a fraction of a second at the start, by ear. After 20 minutes, they were still time-aligned to within a fraction of a second - that's how reliable I have found the KAB to be, and how stable, on average, the belt-driven VPI speed can be (though again, "instantaneous" accuracy is still not as good as the super 'tables).

Next, re-set speed with the KAB, LP and all weights, but this time the stylus was not in the grooves. After 20 minutes, the turntable was clearly behind the CD by a couple of seconds.

It will be interesting to see how the picture changes when I install the silk thread, especially with respect to "instantaneous" speed accuracy.

 

[audioblazer]

It's not lightweight, exactly the opposite, and much heavier than the VPI center weight I use, which is heavy by itself. Thus, a measuring device that affects the system under test is just a flawed measuring device; but in this case, if you also use it as your center weight, it's a fine device.

I doubt the Sutherland timeline strobe weight at 9.7oz has any impact on the accuracy of the speed measurement. A stillpoints isolator weight at 22 oz didn't slow down my AFO in any way . If it's true , then nobody should use shun mook or harmonix clamp which is much heavier

 

[Billy Shears]

Which is one of the reasons why it is a good idea to control the speed of the platter , a lá GPA.
Keith

All i am saying is you cant use a heavy platter with one strong AC motor and then pretend stilus drag does not exist any more.
I have to factor in the stilus drag when seting the speed on the Microcontroller.

Keith It depends how the "on the Fly " speed contols are implemented and if the manufacturer has done his homework. I am not going to say there is only one magic bullet against this problem.

 

[microstrip]

All i am saying is you cant use a heavy platter with one strong AC motor and then pretend stilus drag does not exist any more.
I have to factor in the stilus drag when seting the speed on the Microcontroller.

Keith It depends how the "on the Fly " speed contols are implemented and if the manufacturer has done his homework. I am not going to say there is only one magic bullet against this problem.

It is just fundamental physics - any rotational system at constant velocity will change its speed if you exert any kind of variation of drag on it - either at the stylus or at the bearing. Many systems rely mainly on the moment of inertia of the platter to damp these small variations and reduce them to non audible condition. Belt drag, belt elasticity, platter moment of inertia and motor torque play an important part in this optimization.

Servo types try to compensate it actively, keeping absolute speed. They rely on the sampling of the actual speed and correcting it when they detect an error. There are many ways of doing it, some seem more successful than others. As always, it is a problem of amplitude and frequency.

And then we still have the mixed type, such as motors with servo driving platters versus a belt, reading the speed at the motor or at the platter. Do they combine the good things of both systems or their faults?

Any turntable has its sound signature. As far as I know, except for extreme or faulty cases, no standard measurement is able to correlate with subjective sound attributes. The main problem of carrying measurements in turntables is that due to the limitations of vinyl pressing the test LPs and the reading system have more errors than the platters themselves, and many manufacturers must use non standard measurement techniques to develop and check the performance of their turntables.

The type of drive indirectly affects many aspects of turntable sound - the turntable is a mechanical resonant system and each approach has its problems to solve - e.g. a direct drive motor correcting speed will always send some kind of vibrations to the chassis - it is applying variable forces to the platter that exerts an opposite reaction.

 

[microstrip]

I do not see how the Timeline can be considered a flawed device. If mass is added to the center of a rotating object, it should increase stability, not the opposite. If anything, the motor should have more control over the spin. I'm not saying the Timeline is the supreme measurement device, but it is extremely competent at the job of determining the consistency of a turntable that spins at the standard accepted speed of 33 1/3.

The device in not flawed, but most of the conclusions I have read taken on its use are wrong - people extrapolate too much on the audible effects of the movement of the red dot.

The device only shows deviations at 33.33/60s time intervals - too low for any serious diagnostic. People having a DD turntable, a Sutherland TimeLine and lots of free time could however check for the spread of the point line placing the Timeline at regular small angular intervals on the platter - they will get a differential measurement versus rotor position.

BTW, in some cases putting more mass can upset the servo system - is was optimized for a determined mass. Adding mass will also probably increase bearing drag.
In the old DD days I remember reading that some manufactirers clearly stated that we should not add heavy mats to their turntables.

 

[ddk]

I use a Monarch PLT 200 Laser Tachometer to set the speed on my Clearaudio master innovation TT. I feel is it more accurate and easier to use than the timeline.

http://www.monarchinstrument.com/product.php?ID=24

Accuracy: Optical:±0.01% of reading

Can you hand hold the laser or does it need to be tripod mounted?
david

 

[rockitman]

Can you hand hold the laser or does it need to be tripod mounted?
david

you can hold it, but I feel using a mic stand or tripod to clamp it gives me a better feeling of an accurate reading....

 

[ddk]

Thanks Christian!
david

 

[ack]

I feel Rockitman's device, which was discussed a while ago in these pages, is the best device to use.