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

Okay, here's another version of the question...

I have a VPI TNT IV, which came with a single idler flywheel, (not the extra three you sometimes see around the edge; apparently, there are quite a few versions of TNT). The base has three holes for the weird three-point idler mechanism but mine doesn't have it. The motor drives the idler flywheel, which is very heavy and has a larger diameter pulley than the motor, then another belt from the flywheel idler drives the platter round and round. I'm sure the idler flywheel is designed to both separate the motor from the platter, and with its weight, damp any transferred motor vibration and speed variation.

Since VPI got rid of the idler flywheel for later models, I've been toying around and did that, too..

So what happened? Did the world fall apart?

Honestly, I can't tell the difference. And without the idler flywheel, the whole turntable "package" makes a much smaller footprint. With and without the idler flywheel, I've been using the odd but yes-it-works-great piece of dental floss to drive the turntable platter. And the VPI SDS speed controller in both cases (the only way to get 45 RPM), so the only A/B difference is eliminating the flywheel idler.

The base it sits on is very heavy and damped, and it's using the stock VPI spring-loaded isolation/leveling feet which supposedly aren't the cat's meow but seem to work fine for me. The stock 12.5 tonearm with a Shelter 90X cart.

Anyone's thoughts? Has anyone else tried just simplifying the drive that way? It certainly looks more steampunk with the extra belt and idler gizmo, but simplicity is appealing. What intrigues me is this is essentially what VPI did in later models.

I have a lenco on a massive aluminium plinth and no more noise than a belt drive. I had a pink triangle pt too before.

Hi Tom
I went through many threads years ago with the vpi table. With the verdier i do have his French thread but prefer one i found at fabricland. Gutermann but the exact one i need to look further.. the deck has  been designed for thread so its string/thread is applied very loose. This technique would never work on a belt drive being converted to thread.

In a bit of a crisis as i up at the lake and my lenovo, not to be confused with lenco, just died on me. Bears can’t provide me with spare memory cards which i think it is. I selfishly ask for help from almarg or others here. It is beeping 3 times will not power up. I have tried reinserting the memory card. Did not work.

Re: lenco. Just an observation.

From three decks l75 i found when used in the actual speed slot, the notch for say 33.33 they run fast. Is this by design to deal with stylus drag? Idk. The swiss engineers were very smart and the motor itself a thing of beauty - to me. But it is all hooked up to a mechanical wheel. Setting the speed a little slower is a bit of a pita, but once set it runs fine other than what i noted in previous post. But all that damping in the plinth does have its effect. It is very musical just not as extended as my other deck.

Sorry for any typos - hate using this forum on a phone.

Hi Richard,

Thom
Have you considered introducing a little series R Into the power supply and scoping the motor current draw to vicariously look at stylus drag as a function of motor current draw?

Yes.  I've been wrestling with capturing the time domain of interest.  Our ears are so discerning in comparison with instrumentation, that sometimes, I feel that efforts like this are futile, and so, I put them off for another day.

Thom @ Galibier Design

Hi ct1057,

Re: lenco. Just an observation.

From three decks l75 i found when used in the actual speed slot, the notch for say 33.33 they run fast. Is this by design to deal with stylus drag? Idk. The swiss engineers were very smart and the motor itself a thing of beauty - to me. But it is all hooked up to a mechanical wheel. Setting the speed a little slower is a bit of a pita, but once set it runs fine other than what i noted in previous post. But all that damping in the plinth does have its effect. It is very musical just not as extended as my other deck.

I seriously doubt this is to take stylus drag into account.  If you think about it (and accept stylus drag as influencing speed stability) then it would exist at 33.33, 34, 45, etc.

Cheers,
Thom @ Galibier Design