Direct Drive turntables

Hi all, thanks for your threads.
I recently cleaned my TT,and inadvertently had the belt twisted w/o knowing it. Something immediately didnt sound right so i checked VTF and platter speed. They were the same as before cleaning. Then i realized the belt was twisted, and correcting that at once normalized the sound. The belt on my TW acustic TT goes round three motor pulleys. Even with a twisted belt, the speed was dead on with a strobe disc. Didnt even waver. I assume a twisted belt is bad for speed stability and in this case caused the problem at hand. So perhaps the strobe disc is not sensitive enough to pick up the speed "jitter" or it was something else caused by the twisted belt that degraded the sound.
Happy New Year.

One of the posts above mentioned a wobble in the VPI rim drive. That is a common problem of poor setup. My rim drive is absolutely stable and sounds fabulous.

I have had an opportunity to listen to DD, Rim drive and belt drive on essentially the same turntable and there advantages and disadvantages to each.

Belt drive is by far the easiest and least expensive to get good results. The isolation afforded by the belt hides motor flaws and cogging. But it does so at a price.

Direct drive is brutally revealing of even the most subtle problems with the motor. A typical single phase AC motor would be unlistenable on a DD turntable. But a good DD implementation provides some goodness that in my experience you just can't get with belt drive. The goodness includes the much talked about rhythm and pace but also a bunch of other positive attributes like clarity, low level detail, air, etc. It is really difficult and expensive to do DD right. So with a small to modest budget I would choose a belt or rim drive.

I see rim or idler drive as between belt and DD. Rim drive offers some isolation but far less than belt drive. Rim drive offers the same positives of DD but a smaller dose. Rim drive is somewhat forgiving of motor flaws (cogging) but less than with belt drive. Rim drive is a little more complicated than belt and done right will often be more expensive because of the higher demands on motor quality. I think that rim drive is where the best value hits. Rim drive is relatively easy to get right and in my opinion offers significantly better performance.

This is how I believe that the drive topologies stack up. But it actually says little about how turntables using these topologies will compare. With any turntable you are hearing the whole package and the drive topology is just one of many pieces. The well respected SL-1200 gives people a taste of the goodness of DD but at the same time you get the sound of a lightweight resonant base a flimsy platter and an inadequate power supply. Not that I don't like the SL-1200. At it's price point it is very good, but it is not representative of what a really good DD table is capable of.

Had them all from Linn to Lenco, to Technics and Teres rim drive and my own observation comes down to balancing acoustic isolation of the whole deck and arm , with speed constancy and reducing bearing / plinth noise transmitted back through the vinyl. Probably not enough work has been done on cause and efect of different mats.

For me (emphasis on the "for me") has been on the obvious superior performance of air bearing decks as a major step up in performance over anything else, DD. Rim or belt in overall balance.

Rim drives give slam, belts give body and weight, DD give air and transients - but air bearings ........ the truth!

Steve

lots of sound logic (pun intended) in these posts. the last 2, from Teres and Radical Steve, ring true with me.

i'm a direct drive 'preferrer'....and also enjoy what a good idler can do for musical enjoyment with it's added 'spice'. i've heard many belt-driven tt's that play music wonderfully (but could be improved with well executed dd). so really it all can be good according to execution.

Teres' point about ranking sonic performance (belt -> rim/idler -> dd) and difficulty of execution as the motor gets closer to the 'music' sounds right, as does Radicalsteve's point about 'air bearings' and 'heroic' over-the-top solutions to minimizing the noise and resonance that also echo my personal experience.

i have the Dobbins Garrard 301 as well as the Dobbins Technics SP-10 Mk3. compared to belt drives in my experience there is a certain continuousness and sure-footedness on peaks that even very good belt drives cannot match. the high performance belt drives are good in these areas, but just not as good. these characterisitics live in the timing of the music and are not to be denied. when a piano or stringed instrument is properly recorded idlers and dd have valuable advantages.

then there is noise and resonance control. my direct drive Rockport has the eddy current true cogless motor with an air bearing. it has the 55 pound platter. then there is the active air suspension, the linear tracking air bearing arm, and the vaccuum hold down. you take the direct drive advantages executed to the extreme, and eliminate the noise. now you are at the edge of what is possible.

maybe belt-drives that have some of these other advantages have their own form of magic, but if i had to choose my priorities as one moves up the food chain......direct drive or idler (maybe rim) would come first before belts with air bearings. the timing of music seems most critical to the enjoyment level (my personal perspective--YMMV).