Vintage Japanese DD Consult and Suggestions Please

@alexv Thanks for the starting formula.  i was an indentured servant in a pattern shop, i am fluent in adjusting for shrinkage…

The armboards on my dual arm plinth are 30 mm Aero grade hardened / anodized aluminum. in the well on the plinth i’ve added Kinetic sand. I’ve got a few wood armboard in work including Ebony root and purpleheart and Panzerholtz. i have a lot of respect for Franz as i run his imo lovely sounding CAR-40.

@lewm i believe a good deal of the magic of the big Denon are due the split platter and the magnetic pulse speed control system on the inside rim of the platter. Glad you mentioned platter. I should probably get an SP-10 of some ilk and muck about with that…

best to all in music

westcoast, JP Jones is a professional in the field of electronics. (I don't know exactly his degree level; he could be an EE or a physicist.) Until recently, he ran a business (Fidelis Analog) dedicated to the care and feeding of Technics DDs.  It was my good fortune that he agreed to look at my "broken" Victor TT101, where he found a trivial but near invisible problem (a crack across a tracing in a PCB hiding under a blob of solder and causing a maddening intermittent speed problem) that eluded several other smart guys, and he fixed it. As you may know, he designed and built a PCB using discrete parts that replicates the function of the unobtainable chip that governs speed of the SP10 and lower level series of vintage Technics tables, and yet is small enough to directly replace the chip in the power supply (MN8042 is the chip designation, going only on my memory of the alphanumberic code). Therefore, he was able to test performance of the tables to a level and using methods that I don't completely understand. I bought my SP10 Mk3 in NOS condition, and I did not need to replace the chip, but I did it anyway, because JPs PCB outperforms the OEM chip out at the 4th or 5th decimal place where it probably does not matter much. So I take his comparative analysis of the 10R vs the 10 Mk3 seriously.  He owns both.

Tomic, yes the platter is both a virtue and a potential Achilles heel of the Denon DDs. (If anything should happen to damage the tape glued to the inside rim of the platter, I think it's curtains for the TT.)

lewm, JP may substantiate this but I believe his chip replacement is for the SP-10 Mk 3 and the SP-15.  It is not a replacement for any of the SP-10 Mk 2 series.

Pryso, It was my impression that the MN6082 was used in the MK3 and in many if not all of the original 1200 series TTs, and probably the SP15, as you say, but I am not sure either way about the MK2. I would have thought it was also used there but could be wrong. I think JP has left the building but not on the irreversible path taken by Elvis, fortunately.

Aha! I just did a quick search.  Apparently the MN6082 was only used in Technics TTs that have variable pitch. That would not include the Mk2 but does include the others.

@laaudionut

I have a SP10 Mk 2, PD444, and LO7D and would add simply that all three are great choices.  Each will likely need to be re-capped if not already serviced.  All are satisfying in stock form, but will benefit with addition of modern footers and siting, re-lube, silicon nitride bearing, etc.

Overall the Luxman is probably the most satisfying in terms of reasonable cost, superb vintage esthetic, flexibility in adapting modern or vintage tonearms, and simplicity of maintenance/DIY speed adjustment as per factory service notes with a multimeter.  I found that its plinth design can be improved by substituting thick brass in place of the stock steel armboards.  For a further reduction in plinth resonance, I replaced the archaic stock RCA switch box attached to the bottom of the plinth with a solid wood subplinth that serves as a pedestal for a third arm base out front that accepts standard Micro Seiki cantilevered armboards.  All in all a great piece that is seldom discussed relative to other vintage DD.