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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!
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thom_at_galibier_design's avatar
thom_at_galibier_design
729 posts
 
Hi Cleeds,

I’ve seen this claim before, but never seen any proof of it. I’ve measured the speed of my turntable with it 22-pound platter as it plays an LP and never detected this sort of speed deviation.

I stand (partially) corrected ... primarily because I didn’t want to blow my own horn. I’ve seen stylus tracing induce speed instability on some turntables but not on Galibiers. Mass absolutely helps.

Cheers,
Thom @ Galibier Design
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cleeds
5,944 posts
 
decibell
I believe it is safe to say that maintaining absolute platter speed in the presence of an ever changing load (friction from needle tip) is physically impossible!
Please explain how the speed of a 22-pound spinning platter can be altered by a stylus whose force is measured in grams.

Please tell us about the measurements you've made that support your belief.

Belt drives with very long and flexible belts allow more platter movement - idler drive systems with direct coupled idler connection and stiff motor support allow very little angular platter movement with same amount of torque applied to the platter.
There's no "angular platter movement" on my belt drive table. It's a VPI.
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cleeds
5,944 posts
 
thom_mackris
... I’ve seen stylus tracing induce speed instability on some turntables but not on Galibiers. Mass absolutely helps.
Agreed! If the movement of a phono cartridge stylus affects the speed of a turntable, there is something very wrong in the turntable's design.
harold-not-the-barrel
895 posts
 
Stylus drag is surprisingly strong, platter´s very high mass helps but does not eliminate it. 
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cleeds
5,944 posts
 
harold-not-the-barrel
Stylus drag is surprisingly strong, platter´s very high mass helps but does not eliminate it.

I'm with Thom. There's absolutely no measurable or audible slowing of a turntable platter caused by "stylus drag" if the platter is of sufficient mass and the rest of the turntable is properly designed.

Of course, if you're using one of the common, cheap, lightweight turntables, then I suppose it's possible.
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