I have been listening to a Kenwood L07D. Its designers were thinking along the same lines as you, Hiho. In essence, they have taken a (coreless, brushless) DC motor (with inherently very low cogging, which is an issue they discuss in the owners manual) and isolated it in a very stiff, low resonance, energy absorbing structure, moving all electronics outboard. But they did not stop there; they accounted for the tonearm as well and its linkage to the bearing. This was 1980. Sounds wonderful too.
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.
_________
Showing 9 responses by lewm
Dear Tim, I think the business of torque is over-stated both for its virtues and its problems. The motor, any motor, does not use its full torque unless or until there is an equal force opposing its rotation. So if you turn on your turntable and prevent the platter from turning with your hand, then and only then does the motor develop its full torque. In real life, this only occurs for a brief moment at start-up, when the motor has to move the platter from rest. Once things are up and running, the torque necessary to keep the platter in motion at a constant speed will be determined at any given micro-moment by a number of other parameters, which have been discussed here and elsewhere ad nauseam, but IMO huge amounts of torque are not necessary when playing an LP and are not generated either. So in fact it could be argued that a DD motor might present less of an endogenous vibration problem vs belt-drive or idler-drive motors, because it is spinning at a much slower rpm compared to the other two. Nevertheless, I think your point, so far as we limit the problem to vibration rather than high torque, has validity in that one cannot decouple the motor from platter in DD, whereas such strategies do work and are feasible with belt- and idler-drive types. So if the motor is inevitably closely associated with the platter, then there must be limits as to what can be achieved by isolating the entire tt with a suspension. This is what bugged me when I started to think about using a heavy, dense plinth in the first place for dd tables. But it does seem to "work". I will say one thing - I never liked the "sound" of the Goldmund Studio back in its day. |
Hiho, Great idea about the magnetic or other drive to "connect" the platter to a dd motor. I know it's good idea, because I have thought about it, too. (Heh-heh.) The problem is that if you are a direct-drive purist, any such coupling mechanism could defeat the virtues of direct-drive. I have never seen the EAR turntable, but I have imagined that there must be some elasticity of the magnetic "connection" between motor and platter in their magnetic drive system, which takes us back to the disadvantages of belt drive. I guess if you have a VERY powerful magnet and if the airspace between driver and driven is VERY small, then you would have almost zero elasticity. |
Well, I have only one hour of listening on my Kenwood. Plus at the moment I am restricted to using the Kenwood tonearm only on the Kenwood. But I can imagine that the Kenwood is the "best" sounding of the three units, with the other two mounted in slate plinths. However, I could easily live with either of the other two as well. The DP80 is a "sleeper" in terms of bang for the buck, if it is first properly restored electronically and then dampened in several ways, including the use of a good plinth. By the way, the Lenco L75 in slate on a PTP top plate, etc, is no slouch either. |
Hiho, What about the SP15 and SP25? How do those compare to the ones you listed above as donor tables? They are way less expensive than any SP10. You guys got me thinking (again) about separating the SP10 Mk2 motor from its chassis and on-board electronics. I have been able to resist the temptation so far. As long as this stuff does not get in the way of my ability to listen to and enjoy LPs, I am ok with it. This is the one advantage of having several turntables. |
Thanks for sharing. That's really nice work. You can see a rather poor photo of my slate Lenco in my system post here on Audiogon. Plinth is a monoblock of slate, unlike yours. Used Peter Reinder's top plate. Probably should post it in Lenco Heaven as well. I run it thru a Walker Audio Motor Controller, but I am in line to receive a Mark Kelly controller specifically designed for the Lenco motor. |
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, 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".) |