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want new plinth ideas for direct-drive turntables


By now, the idler-drive genre has enough ink on them without me adding anything new to the topic. What is little talked about is the "guts" of direct-drive tables. Many vintage DD units suffered from bad plinth design with inadequate solidity (often mounted to crappy plastic or flimsy particle-board) and inadequate isolation from resonance and interference of electronics.

I like the bare bone approach, that is, to take the motor out of the chassis/plinth/enclosure and mount it to a something solid, material of your own choice, and extend the cable by at least couple feet to the stock chassis or an enclosure that contains the electronics/motor-drive/control-console/power-supply. In fact, the Monaco Grand-Prix, Teres Certus, or early Micro-Seiki DDX/DQX-1000 takes the same approach.

Almost ALL DD tables can be improved this way. There are many other brands of superb DD tables with great potential out there can be had for very reasonable price and can be converted this way with good result. I no longer have any Technics tables on hand to experiment but I still got great results with some mid-priced JVC, Pioneer, Kenwood, Yamaha, etc... I haven't tried it on Sony and Denon tables yet because they require mounted a tapehead to check platter speed so the mounting is tricky. Modern belt-drive turntables have been doing similar things by separating the motor from the main plinth. Once again, Micro-Seiki was ahead of their time with their RX-1500 and beyond. It's only logical DD will go that direction. The days of having everything in a box for DD tables seems less attractive to me now.

If you have other ideas, feel free to talk about it here. And hopefully this will generate more new interest in the DD genre. Personally I am more interested in people's experience with brands other than Technics as they already got enough coverage in other forums and threads. Nothing against Technics, just want to direct attention to other sleepers out there. Anyway, still feel free to share ideas.

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hiho
lewm
13,308 posts
 
Hiho,
I noticed this Sansui on eBay and have done a little reading about it on Vintage. The motor seems very advanced, and the plinth is at least partially constructed with resonance in mind, altho there is an outer MDF layer for cosmetic purposes. Do you know anything about it.

http://cgi.ebay.com/SANSUI-SR-929-Quartz-Locked-Direct-Drive-Turntable_W0QQitemZ170470092387QQcategoryZ48649QQcmdZViewItemQQ_trksidZp4340.m8QQ_trkparmsZalgo%3DMW%26its%3DC%26itu%3DUCC%26otn%3D20%26ps%3D63#ht_500wt_962
hiho OP
451 posts
 
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I never own any Sansui turntable, even though I am a huge fan of their tube gears - awesome output transformers. I am not familiar with that model but I don't think the motor is all that interesting. And judging by the look of it, they might have outsourced it from Denon. As a turntable, I would rather choose their later day coreless motor models like XP-99 or XR-Q7. As you know I am a big fan of coreless motors - super smooth sound. The attraction for me is the tonearm as it is knife edge design a la early SME but the horizontal movement is an inverted bearing on sapphire disc. Very unique for its time. Anyway, the table seems well built and might be a good performer.

Almost all info on Sansui turntables can be found on this site:
http://www.classicsansui.net/Turntables.htm

I have read about Sansui's latter day designs in addressing the counter torque issue with direct-drive motor by adding another motor underneath running in reverse to cancel the vibration. Not the most elegant solution but at least they acknowledge the issue. I much prefer Steve Dobbins' simpler and more elegant solution by decoupling the stator coil from the bearing assembly. Judging by the look of theXR-Q7 motor, Sansui might have outsourced that from Sony as it just like the BSL (Brush/Slot-Less) motor from a PS-X40, PS-X70, and others, even down to the tapehead servo system. Those BSL motors have rather flimsy construction on the bearing well as it is mounted on plastic(!!) as my PS-X65 got damaged in transit due to bending plastic. Maybe Sansui improved on it. Anyway, those two models, XR-Q7 and XP-99, are the only Sansui turntables have any attraction to me. Unless I find a beater XR-929 so I can scavenge the arm. :-)

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lewm
13,308 posts
 
Hiho, Thanks for your expertise in this area. The XR-Q7 looks like a Micro Seiki with only a label change. Since M-S is credited on Vintage Knob with the design and/or manufacture of many tonearms and turntables that do not carry the M-S name, I am inclined to believe it IS a M-S product. (This is a GOOD thing, of course. The XR-Q7 would likely cost a lot more money these days if it were labeled "Micro-Seiki".)
hiho OP
451 posts
 
You don't need Sansui or Micro-Seiki for direct-drive, because you already own one of the best DD tables ever built, the Kenwood L-o7D. :)

I own a Kenwood KD-770D and it's super smooth with probably the lowest torque among DD tables. It has a fluidity almost like a belt-drive but DD speed stable. Again, a coreless motor unit along with its bigger brother KD-990D. I can imagine how nice the LD-07D can be... I believe it's a high torque design so its bass must be awesome. Lucky you.

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