Chakster, If you see Harold's follow up post, it seems that he really found no substantive fault with his PD444, except that you could say it was too perfect, and he prefers his belt-drive. Personal taste has a lot to do with this.
Harold, From what you say, perhaps your PD444 needed no servicing, but it's impossible to know for sure except to say it wasn't grossly malfunctioning. As to servicing, the schematics for most of these vintage DD's are available on-line, and for a knowledgeable tech with the proper equipment, which is pretty basic stuff for a pro, calibrating a DD is no big deal. For sure, you would not have had to send it back to Japan. For example, I have the schematics for the L07D, the SP10 Mk3, the DP80, and the TT101, available from Vinyl Engine or Soundfountain (the SP10 website) or other on-line sources.
With respect to the general question posed by this thread, I would point out that the modern trend in the most advanced belt-drive designs is to have an outboard motor controller. A subset of those devices incorporate a feedback mechanism that transmits platter speed errors back to the controller which then sends a message to the motor to correct the error. In addition, we have the recent outboard devices, like the Phoenix Engineering pieces, that set up a feedback mechanism for platter speed control and can be added to even older belt-driven or idler-drive turntables to improve speed stability. So, it hardly seems logical to disparage direct-drive turntables for incorporating a quartz-locked feedback mechanism that makes speed corrections. (Does Fremer realize this?) If servo systems are so bad, why is the trend toward adopting similar mechanisms? True, it can be done well or done badly in any case. If done badly, I imagine it could introduce an audible kind of distortion, but I also think the problem is over-rated by those who prefer other drive systems.
On the DP80, if you select the option to adjust speed, you give up the quartz-locked loop circuit, and the speed constancy could be less good. I don't know how speed adjustments are achieved on the TT101 or on the SP10 Mk3. The TT101 may have a series of discrete quartz-locked circuits, selected on the front panel, one for each selectable pitch.
Harold, From what you say, perhaps your PD444 needed no servicing, but it's impossible to know for sure except to say it wasn't grossly malfunctioning. As to servicing, the schematics for most of these vintage DD's are available on-line, and for a knowledgeable tech with the proper equipment, which is pretty basic stuff for a pro, calibrating a DD is no big deal. For sure, you would not have had to send it back to Japan. For example, I have the schematics for the L07D, the SP10 Mk3, the DP80, and the TT101, available from Vinyl Engine or Soundfountain (the SP10 website) or other on-line sources.
With respect to the general question posed by this thread, I would point out that the modern trend in the most advanced belt-drive designs is to have an outboard motor controller. A subset of those devices incorporate a feedback mechanism that transmits platter speed errors back to the controller which then sends a message to the motor to correct the error. In addition, we have the recent outboard devices, like the Phoenix Engineering pieces, that set up a feedback mechanism for platter speed control and can be added to even older belt-driven or idler-drive turntables to improve speed stability. So, it hardly seems logical to disparage direct-drive turntables for incorporating a quartz-locked feedback mechanism that makes speed corrections. (Does Fremer realize this?) If servo systems are so bad, why is the trend toward adopting similar mechanisms? True, it can be done well or done badly in any case. If done badly, I imagine it could introduce an audible kind of distortion, but I also think the problem is over-rated by those who prefer other drive systems.
On the DP80, if you select the option to adjust speed, you give up the quartz-locked loop circuit, and the speed constancy could be less good. I don't know how speed adjustments are achieved on the TT101 or on the SP10 Mk3. The TT101 may have a series of discrete quartz-locked circuits, selected on the front panel, one for each selectable pitch.