Direct Drive vs. Idler Drive vs. Belt drive

Dear @rauliruegas

i’m not anti-servo, but appreciate the liquidity and tonal density that absolute steady speed and continueousness can deliver. maybe this explanation will help you to understand what a properly designed non servo turntable can deliver.

In order to pick up sound accurately from the analog disc, the rotation of the platter must be rotated at a constant speed without any “fluctuation”. In general, accurate rotation is obtained by servo control by negative feedback, but at the micro level, if it rotates or becomes faster, it detects it and slows it, and repeats the operation to make it faster if it gets slower. Although this level and cycle are determined by the gain of the control system and the loop speed, the period of the speed control of the platter which is the mechanical system surely comes into the audio band. In general, accurate rotation is obtained by servo control by negative feedback, but at the micro level, if it rotates or becomes faster, it detects it and slows it, and repeats the operation to make it faster if it gets slower. If you try to measure a period with a small level, you can not measure the instantaneous state, so you measure the average value. Therefore, fine vibration generated by servo control can not be measured by the measuring instrument, it depends on the human ear.

my ears tell me it can be better (i prefer it mostly when properly executed) without the servo.

but this is not to say that turntables with servo’s are not fantastic at playing our records, they simply are not the pinnacle at steady-ness.......and the benefits that can bring.

at modest build levels this theoretical stuff is lost in the execution. it takes fairly heroic design and build efforts to allow non servo to show it’s stuff. 

Dear @mikelavigne : With servo or optical or whatever speed controller we use it happens exactly the same:

" but at the micro level, if it rotates or becomes faster, it detects it and slows it, and repeats the operation to make it faster if it gets slower. "

The TT platter rotation speed is affected by to many circumstances not only if the motor is DC or AC one and it does not matters the drive kind of design TT has.

Some of those circumstances that affects speed stability in the extremely short period of time are: stylus drag at high velocity LP recorded grooves and this could happens any time at any LP surface positions, electrical power source, even some one detected that static developed can impair the function of the speed controllers by million of a second time periods, non perfect flat leveled TT that could affects the platter bearing stability, as the cartridge stylus tip the TT bearing goes degrading through the time, belt degradation, pulleys suffers of that degradation too as the ID internal mechanical parts, even the speed controller has a time degradation too.
All those circumstances and many others makes a TT imperfect item suceptible for the speed controller goes in/out trying that the speed stays stable in the very short time.

That’s why I ask for mosin/jtinn or any other TT manufacturer in this thread but even if no one can comes the reality is that you can’t detect it those extremely fast speed rectifications because you can’t detect those speed rectifications that were do it for the cutting lathe through his speed servo controllers. The cutting lathe Technics motor ( SP02. ) use the same servo than the SP10MK3 ! !

But all those cutting lathe motors are way vintage designs and even that old speed controllers designs you can’t detect it those servos in any of your LPs played trhough the Saskia or CSPort ! !

You can stay entitled to your way of thinking but it’s only that " a way of thinking " a subjective way and not a true fact/objective because you can’t hear it in any TT drive design at any price levels.

Now, it’s not here if you are rigth or wrong but the matters is if really exist what you think or just does not exist as I support.

I know very well @lewm and he owns ID and DD different TTs and that I remember he never posted that can detect a problem about but it’s not the only audiophile because there is nothing that proves that non-existent symptom. Other gentleman is @cleeds and I can name you several more including the gentleman you know very well that’s an AS BD all metal design distributor or manufacturer ( I’m not sure about. ), the one I linked the wbf here.

Mike, with all respect: as a cartridge or speakers or electronics any TT design is the sum of its parts inside the whole design and you are taking only one part/characteristic/parameter of that whole design where things are that all TT designs, one way or the other, shares in between no matters what.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

Mike, I do not think it takes such heroic construction to make a synchronous or three phase motor drive to function at the state of the art. Those of us that do not have the kind of resources you have have a host of choices that also include adequate isolation unlike your Saskia and CS Port turntables which will freely pass on environmental rumble unless you have placed them on an isolation platform, an additional expense. 

@mijostyn,

agree completely.

i intentionally did not mention dollars, but degree of effort. it’s not trivial to have the right bearing/platter/plinth/motor assembly to get a great result.

there are many giant killer turntables. but lots of ordinary ones too.

just having a belt or idler and no servo is not sufficient.

regarding the CS Port LFT1 it has considerable mass (both plinth and platter) and an air film suspension and air bearing (low flow, low pressure) all contributing to low noise.

the Saskia has a 180 pound plinth + 40 pound platter and built in suspension. all that mass in all the right places does help to make it easily the quietest idler i’ve heard.

but there are pressings where my active shelf takes the NVS to another level of precision.

both the CS Port and Saskia might benefit from a Stacore shelf. i say ’might’ because with isolation you have to try it to know whether it helps.

@mikelavigne 
Have you done the spin test with any of your current TT’s Mike ?
I disconnected the belt from my Maplenoll yesterday, and gave the 100 lb platter a spin. It took 45 min before it was stopped completely, i was expecting 10 min or something like that.