Vintage DD turntables. Are we living dangerously?

Dover, I've got a fully refurbished L07D sitting right next to a Krebs-modified SP10 Mk3 which I bought NOS (before replacing all electrolytics and having Bill Thalmann perform the Krebs mod). These are easily the two best turntables I have ever heard in my system, yet they sound very subtly different. Before the Krebs mod was performed on the Mk3, I would say the difference between the two was greater than it is now, in favor of the L07D. But of course, there are more differences between the two than those having to do with the drive system: The tonearms, tonearm wire, and phono cartridges are all different as well. They both feed into the same Atma-sphere MP1 phono stage. But it's fair to say that prior to the Krebs mods, I tended to favor the L07D (with an EMI/RFI shield installed between motor and underside of platter). The Krebs mod keeps the virtues and advantages of the Mk3, absolute firm sense of pace, while ameliorating the rather "clinical" nature of its sound, as compared to the L07D, which might in fact err on the side of romantic but intensely "musical". (I distrust that word, too.) These days, I could live with either, happily, but might now give the edge to Mk3. The Krebs mod is transformative.

Richard, I had reason recently to disassemble my L07D motor and then put it back together as well. I do not recall seeing any rubber grommets. What I did see were some nylon grommets and some brass grommets, neither of which afford much elasticity. Is it possible that the motor you looked into had been "messed with" by someone, some time in its past? If you look at the service manual, and if you consult Howard Stearn, the L07D guru who lives in Virginia, you would get confirmation that the grommets should be nylon or brass. Howard talked me through the rebuild process. My memory may be playing tricks on me re the rubber grommets, but I believe this is the case.

Fleib, For all I know, Pierre Lurne' is a genius when it comes to platter design, but I am no fan of any of the turntables with which he was associated. The ones I've heard (Audiomeca, Goldumund Studio, etc) all "suffer" I think both from speed irregularity and an overly spring-y suspension. They are kind of a yin to the yang of direct-drive turntables.

Dover,

"with the DJ market in mind". I trust you were referring to radio station DJs, which were a market for early Technics DD tables, not dance club scratch/mobil DJs. I've read many false assertions the Technics SL-1200s were designed for dance club DJs. I believe the SP-10 and SL-1200 series were designed in the '70s, a time before dance club DJs evolved.

I don't mean to sound picky here but I hate to see the DJ misrepresentation continued for any newbie readers here who may not be familiar with DD design and development.

Lew
The rubber grommets look original.
I will PM you a pic of the stator to compare with yours.
Inserted in the centre of the grommets is a small metal tube stand off to prevent the grommet from being crushed when the bolt is tightened.
There are also a couple of nylon? stand offs to prevent the rotor from contacting the stator windings when the platter isn't in place ( partial mag lev feature)
Anyway, slight stator rotation is permitted by this arrangement and if original it is an interesting design decision.

Lew,
When Lurne was working under contract for Goldmund I imagine there were constraints. The T5 linear arm wasn't held in the highest regard and the DD suspensions were problematic with any arm substitution. Many users including myself defeated the suspension. The Studio came with alternate springs, but most users were clueless about how to substitute.

This is the first I've read of problems with speed stability. These are quartz locked with a JVC motor. Perhaps you're referring to the earlier Pabst motor, but the ones I've heard didn't seem to have speed problems if everything was functional. The Reference was servo controlled belt drive.

Lurne is probably the most copied TT designer in audio. Not sure which Audiomeca you're referring to, but take a look at this design including the suspension:
http://www.tnt-audio.com/sorgenti/belladonna2_e.html

Regards,

Fleib,
Many years ago my friend took his bog standard L07D over to Richardkrebs who at that time had a heavily modified Goldmund Studio. Despite the Goldmund having had many power supply and other modifications and an ET2/Monster Alpha cartridge and the L07D a cheap moving magnet - the L07D highlighted significant speed problems in the Goldmund, particularly in timing and coherency. The Goldmund by comparison sounded like it was lurching around and struggling to get over the line. This is what I believe prompted Richardkrebs to dump the Goldmund for the SP10mk3 that he now runs. I believe that Goldmund had the JVC motor.

I have heard the Krebs modified SP10mkII and to my ears it is similar to the Goldmund Studio, well down in performance compared to the L07D and SP10Mk3, again in loss of timing and coherency. I think it is significant that both the L07D and SP10mk3 utilised higher mass platters than their earlier DD's to assist with speed stability.

And yes by DJ I meant radio stations and the need for quick and accurate queuing.

One further thing to be aware of - out of the five people I know with L07D's, only one has had no "apparent" problems - quartz locking not working properly, hum, noise being the most common issues. So when we audition some of these decks today it is possible that we were not hearing them optimally as they were designed simply due to ageing and drift in components.

Lewm I have heard both the L07D and SP10mk3 with and without the Krebs tweak and agree with your summation, the proviso being that the TT's have been serviced thoroughly and are performing to spec. Bear in mind though that the SP10 requires a lot of work to get it sounding ok - new plinth, mats etc.