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What's the deal with idler turntables and do they have a place in modern HiFi?

After going through a complete overhaul of an AR XA I've been tempted to take a step further back in history and restore an old Rek-O-Kut idler turntable. Can't remember the particular model number from Craigslist, but it seems like it may be an interesting project and far more customizable than the XA, especially when it come to the tonearm. The one I'm looking at comes with the original tonearm, but my guess is that it's even more garbage than the stock XA 'arm and I'd certainly replace it!

However, I don't generally become invested in something if it doesn't pay off. So if the sound is going to be dreadful because it's an idler, then I'll steer clear. But if the sound is bitchin' then I'll jump on the opportunity!
128x128mjperry96
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cleeds
2,065 posts
 
totem39573 posts.
Regarding "stylus drag" affecting the speed of  a properly designed turntable with a platter of sufficient mass:
Not measurable was put to rest forever. This was talked to death in the Sutherland Timeline thread
You're clearly mistaken, because there are two people in this very thread who have contrary evidence. One of them is Thom, a turntable designer. As for myself, I've actually made the measurements, rather than just relying on others' opinions.

It's easy to understand if you think about it. So-called "stylus drag" is a deviation that would be measured in fractions of a gram. If you consider a 22-pound platter spinning on a low friction bearing, it's pretty far-fetched that such a tiny change in force could have such a big effect.

I've even tested this with the Telarc 1812 LP, which has some of the most heavily modulated grooves ever pressed on LP. Note that this is also on a turntable that uses a threaded reflex clamp; that eliminates the chance of the disc itself slipping on the mat, which of course would skew the result.

To be clear, I don't doubt that this is a problem with some LPs on some turntables. And LP playback is surely fraught with challenges. But the effect of stylus drag on platter speed? That's a solvable problem.
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thom_mackris
680 posts
 
I will say this, as far as measurements are concerned. At present, my best tools are the Feickert Pro software and a Timeline, and I’m not seeing any effect (can’t directly measure music with the Feickert, unfortunately). I’ll leave it open to the possibility that at a finer level of resolution, there may be a drag effect, but somehow, I doubt it.

Remember that speed changes occur in varying time domains. At the finest level of granularity, we hear it as distortion. If you’ve never read the IAR review of the Rockport Sirius, the first page of this lengthy tome is a good read for an analog-file. Worst-case, it will cure your insomnia ;-)

http://www.iar-80.com/page12.html

Cheers,
Thom @ Galibier Design
harold-not-the-barrel
799 posts
 
Here´s Teres Audio´s article about http://www.teresaudio.com/manuals/teres_speed_tech.pdf
lewm
6,770 posts
 
The "problem" with this hobby is that there are frequent instances where we have phenomenon A associated with physical fact B, and the natural human response to such coincidences is to ascribe A to B.  But we almost never have good scientific experiments to prove or debunk such associations.  Thus we are all floating in a sea of subjective judgements, and there is an industry based on tweaks that thrives upon our ignorance. (Sorry, but I do not think the Timeline is much better than a well designed strobe, like the KAB, for looking at instantaneous deviations from correct platter speed. However, if you DO see a speed deviation with the Timeline, you do have a problem.)

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almarg
8,673 posts
 
The "problem" with this hobby is that there are frequent instances where we have phenomenon A associated with physical fact B, and the natural human response to such coincidences is to ascribe A to B. But we almost never have good scientific experiments to prove or debunk such associations. Thus we are all floating in a sea of subjective judgements, and there is an industry based on tweaks that thrives upon our ignorance.
Very well said, Lew, IMO. I would add that in audio there are countless variables that can be cited for which it is not readily possible to define a quantitative threshold separating what may potentially be audible in some systems from what is unquestionably insignificant. In the absence of that kind of quantitative perspective there is essentially no limit to what a perceived or claimed sonic effect can be attributed to.

Best regards,
-- Al
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