Dear Lewm, I certainly do not want to get into an argument about idler, dd or belt drive. Yes, I agree - everyone has his opinion. And I do not have any problem with other opinion. But I still see this as not about personal opinions but technical principles.
So please do not take the following lines personally, but just as a technical statement.
Believe me - if there would be a direct drive suitable for a really good turntable, I would have used it.
And I still do have access to every possible drive mechanismen and motor in the very highest possible quality. There is no direct drive suitable to rotate a 100 lbs platter with close to zero vibrations and good constant speed - the problem to begin with is the inertia. The high inertia will get into a conflict with the direct coupled motor - same in idler drive. Both drive mechanism do imply total control of the speed by the motor itself via direct coupling.
Thus why all DD platters are fairly lightweight. The DD gets huge problems with high inertia. In any DD inertia is contraproductive. Let me just briefly explain, that there are at least 3 paramount reasons for using a belt drive for a turntable:
- possible lowest vibration transmitted to turntable by thread
- possible highest platter weight
- possible to use high inertia for self-stabilized speed
At least the last two reasons can not be used with idler or dd drives.
Thats why I can not take those two drives into serious consideration.
I know that I do need a super high mass platter which is acoustic dead to reach best possible performance. This should be obvious from the technical facts displayed earlier in this thread.
The idler drive was well explored and professionell researched by EMT and others in the 1950ies and 1960ies.
I guess we all would agree that one of the best possible ways imagined to drive a turntable would be to apply a constant stream of air (without frequency pulse of course.... BTW - thats a drive mechanism I currently am musing about). The next closest approach to that ideal would be the 'en tangent' thread drive with force free lateral bearing.
However - every technican into dynamics and machines will tell you that high inertia will undoubtly provide the most constant speed possible. Why working against a natural force if it gives you a huge advantage for free?
With both idler and DD you have very direct coupling (with a hunchback of problems....) and the speed is direct related to the motor.
Well, I am really sorry, but it is technically and physically obvious that this is not a good idea......
You may use a turntable with a direct drive or an idler and may be very happy with the sonic results.
Thats fine with me.
And it is your opinion which I respect.
Just respect that I would never use either drive and that I KNOW (physically, technically and from experience) why I do not.
