Vintage DD turntables. Are we living dangerously?

Shane, I would take the dust cover and put it into storage.  You don't want a dust cover anywhere in or on or over your turntable when it's in use.  I thought every vinylphile agreed with that principle. Of course, you could always place it over the plinth when the Mk3 is not in use. Otherwise, those heavy lucite covers are bad karma, in my opinion.

Audiolabyrinth, Unless your turntables have a known history of having been serviced recently, I suggest you may want to replace all the electrolytic capacitors in both, and then have a competent technician calibrate the drive systems.  That's the only way you can be sure you are getting the most out of them, although if they operate without noticeable issues, you're probably OK.  One thing I've observed is that the market values of mid-level vintage DD's like your two is not much below what you would have to pay for the really top quality ones.  For example, you can find Denon DP80s or DP75s for less than a thousand dollars.  Another good one is the Kenwood KD550, which seems to be easy to find for around $500.  You might also luck out and find a Victor TT101 for under $1000; that would be a great bargain, but they are rare outside of Japan. Yamaha GT2000 is another one to look for.  Between one and two thousand $, you can hope to find a Technics SP10 Mk2.  I'd actually rank the DP80, TT101, and GT2000 slightly ahead of the SP10 Mk2, certainly its equal.  Well, you said you were "collecting"...

"I didn't know kenwood made a good turntable".
The KD550 is a fine one, on par with the DP60L, perhaps.  I didn't mention the L07D, which is up there in the pantheon of the really great vintage direct-drives, like the SP10 Mk3, Pioneer Exclusive P3, etc, but those are way up in cost.  You can find a very nice L07D for between $3K and $4K.  The good news is that it is sold as a unit with a very advanced plinth, even by today's standards, and a very good tonearm, designed for and specially adapted to the L07D.

Kenwood made a whole series of components in the L07 series (amplifiers, preamplifier, tuner) that were very high end (and expensive) in their day, comparable to the Pioneer Exclusive line of gear.

Most I can manage is a chortle.  Not laughing all the way.

audiolabyrinth, The cartridge to which you refer could be that Ortofon mentioned by Chakster (I think) or it could also be an Acutex LPM series.  Pickering made some cartridges that resemble the nose of the Concorde, as well.  I suppose many other companies did, too.  For a while, that was a popular shape.  Can you post a photo?

Dear Audiolabyrinth, No, I have never owned a Technics SL1600 or any others in the SL1200 lineage.  But I also don't try to match cartridges with turntables.  What counts is the effective mass of your tonearm. Read up on tonearm effective mass and cartridge compliance, so you can understand what Chakster was trying to say, which I believe is simply that your tonearm is "medium" in effective mass, which means it would mate well with medium compliance cartridges.  There is some good information on Vinyl Engine to help you to define those terms and to identify cartridges that fit the bill.  But also, rules are made to be broken.

Peter, You seem to have taken a very different tack with the DN308 as compared to the DP80, in terms of the design philosophy behind the two very different plinths.  The DN308 plinth seems to have a hollow interior, whereas the DP80 plinth (from photos I have seen elsewhere on your site) seems to have been built from layers of precisely machined wood such that the only available empty space is tightly fitted to the electronics and the mechanicals of the DP80.  I actually prefer this latter approach.  Can you comment? Thanks.

Thanks, Peter.  I will look forward to seeing photos of the DP80 mechanicals in the DN308-type plinth.

As regards JP and the TT101, I can only report that my TT101 had an intermittent glitch that persisted for the first 3-4 years of my ownership, even after replacing all electrolytic capacitors. (I got it cheap, because it was "broken".) The diagnosis eluded two very competent technicians over that time span, until finally I came upon JPs thread on DIYAudio, wherein he was talking about his new chip for the Technics SP10 Mk2 and Mk3. I detected that he had a deep understanding of these circuits. I contacted him and soon thereafter shipped my TT101 to him in NYC. Within two weeks or so he had localized the problem to a microscopic crack in one of the PCB tracings. Shortly thereafter, my unit was up and running, and I have had zero problems ever since, all because JP has the smarts to reason out where the problem ought to have been and then to locate it shortly thereafter. So, Bestgroove, if I were you I would waste no time in sending the TT101 to JP. My unit was the first TT101 he had ever seen in the flesh, by the way. Very impressive.

Best groove, I did not realize you live in Italy. (Lucky for you, by the way.) I don’t know about cost of round-trip shipping to JP in New York City, but I do know that his repair work is very reasonable in cost, surprisingly so in relation to his skill set. The TT101 circuit is very complex, given the "bi-directional servo" system, so I wish you best of luck in figuring out the cause of your problem. You might benefit from talking to JP, even if you feel you cannot afford to ship the TT101 for repair. There are several chips in there, but one and only one of them is the main controller. Of two "broken" units that I know about, including mine, neither of them needed a new chip, fortunately. But I may be able to help you out if it turns out you do need a new controller chip.

Definitely you should start out by replacing all the electrolytic capacitors, unless you know for sure that this has been done recently.  The lifespan of an electrolytic is typically less than 30 years, and shorter still if the unit has been sitting for many years without power.

I've given two TT101 chips away at this point, so I am not sure it's fair to say I have a "stock" of them, but I do think I have a few more, in one of those drawers where you put things you don't want to lose and then forget where the drawer is.  I would always want to keep at least one spare for myself.

Best-groove, No, Lewm does not have some spare for sale.  I cannot supply all TT101 owners, but I may be able to spare one for you for no cost if you really need it.  Assuming I have at least two left in my stash.

I forget the part number for the critical IC, but all I did was Google it, and I found many sources for it, in Asia.  Most are on Alibaba (I hope that's the correct name of that website).  I just chose a vendor who seemed to understand at least a little English.  The cost is cheap, once you find a vendor, because who else wants one, besides the few dozen people in the world who may be fixing TT101s?  Albeit, this was 3-4 years ago when I made my purchase.  One thing to keep in mind is that the chips are around the same age as the TT101, so I suppose it's possible that they can go bad just from sitting on the shelf under god knows what storage conditions, for 30 years.  One of mine was used to repair a TT101, and it worked, is all I know.

First, take some of the stuff on Vintage Knob with a grain of salt; that site is not always perfectly accurate.  
Second, if you can find the IC as an NOS part, via Alibaba or other internet source, it will probably cost a few bucks each.  And you would be MUCH better off at a MUCH lower cost than trying to source the IC by buying a whole turntable.  You would have to pay the cost for a working unit, too.

As to platter mass, the SP10 Mk3 has the heaviest platter that I know about among Japanese vintage DD turntables, except possibly for the optional and very rare gunmetal platter for the Yamaha GT2000X.  But that latter platter will cost you about as much as a good GT2000, if you can ever find one.  (For the heck of it, I have been searching.) The L07D platter is substantial but only a fraction of the weight of the other two.  It can be enhanced by the addition of an optional peripheral ring specifically made by Kenwood for the L07D, which I own but don't use. The SP10 Mk2 platter is not much different in weight from that of the TT101 and the Denon DP80.  I don't know about the Luxman platter; there are a few owners on this thread who may tell us.  One determinant of platter mass back then may have been the choice of motor.  For a given physical size, coreless motors produce less torque than do iron core motors, but the correlation between coreless motors and platter mass is not linear, either, except to note that the Mk3 uses a gigantic iron core multi-pole motor.  The Pioneer Exclusive P3 has an impressive platter and uses a coreless motor, on the other hand. The GT2000 uses a coreless motor but had an optional oversize bearing and that optional massive platter to be driven by that same coreless motor.

Theophile, OK.
I wouldn't think of using that platter without the optional larger and heftier bearing assembly.  Was that available for all 3 versions of the GT2000, as well?  If so, then what is the big deal about the "X" designation, apart from the fact that the standard tonearm on the X was maybe different from the standard? ((Yet, that tonearm can also be fitted to the GT2000, so far as I can tell.) Why would the X be twice as expensive these days as the plain GT2000?  In photos, there are no obvious external differences between the two models, either.

Theophile, Please understand that the question of the gunmetal platter on a GT2000 or 2000X is not on my front burner, as I do not own any Yamaha turntable. Thus I confess only to being human and to having forgotten our previous discussion. In fact, after I posted my previous comment, it did occur to me that we have covered this ground before. Mea culpa.

Also, you seem to think that I dismiss the possibility that the 18kg platter was a significant upgrade to performance. I do not and did not. But because of its far greater mass compared to the standard platter, I personally would not run the 18kg platter unless I had the version of the GT2000(X) with the larger bearing assembly. Personal preference aside, I also don’t think I ever asserted that the 18kg platter could not be used with the standard bearing, if one wanted to do that.

You may also like to know that I have advised others not to purchase a GT750 or any other lesser model of vintage Yamaha DD in the belief the lesser model would be "just as good" as a GT2000. I agree with your assessment of the relative merits, based on data, not personal experience. I have also mentioned here that, because our son has worked and lived in Tokyo for nearly 10 years, I am a fairly frequent visitor. I can attest that the GT2000 is not rarely seen in high end emporia that sell vintage used merchandise. (Typically, the ones I have seen in the flesh were a priori "sold" to some other lucky buyer, before I got there.) They also turn up on Hifido more often than a Pioneer Exclusive P3 or Sony PS-X9, for examples. This is evidence that the GT2000 was very popular when it was current, among Japanese aficionados.

Attachment?

Chakster, Mark seems to have a "no-speed" problem, not an "off-speed" problem.  His PD444 is dead.  To paraphrase the Monte Python description of a dead parrot, it's an "un-turntable".

Mark,  Please see up the thread where I have mentioned many times the fact that JP Jones is good with these problematic gems. I don't know if JP ever worked on a PD444, but he is a fast learner, especially if you can dig up a schematic.  JP posts here, too.  His business is called Fidelis Analog, located in NYC.  Also, Dave Garretson, another member of this forum, owns a PD444; Dave is a pretty smart guy as well.  Best of luck; your PD444 is worth the effort and cost to make it run again.

PS.  No need to do the Jonathan Cleese imitation. But do bring the parrot with you.

JP hangs out here once in a while. Or else I think I have his email address. Or failing even that, he may have a website under Fidelis Analog.  He's a very straightforward guy, so go for it.

Found it: JP@fidelisanalog.com

I had a moment of doubt myself. Google seemed to indicate "Jonathan", but my instinct told me "John".  I obviously chose Google over instinct.  Today Google agrees with you and my instinct as well.  I don't know what I was looking at yesterday.  Does any of this matter?

I certainly owe Raul an apology for doubting him.
Raul, I apologize. Wherever you are.

The SAEC mat is not prone to slipping on the platter surface even without tape and without drilling the LP, but I do use a record weight and will continue to do so. The drilling seems to have been recommended to prevent the LP from moving with respect to the mat. Live and learn.

Nothing Fawlty about my logic.
Chakster, the person whom you quote here has got to be Thuchan.  Who else owns such a collection of vintage turntables?  Moreover, in one of the articles, I am "Lewis".  I gave Thuchan a chip to repair his TT101.  And what Australian could he possibly be referring to, if not our own Halcro?  If I read his words carefully, it seems to me that Thuchan is only saying the TT101 compared surprisingly well to the Denon DP100.  He does not really say he likes it better than his EMT and M-S, and I don't think he owns an SP10 Mk3 or L07D.  Whereas, I do.  Like Thuchan, I bought my TT101 in "broken" condition off eBay, believing at the time that I would find a way to fix it.  The saving grace is that I paid very little for it, because of its non-working condition.  Elsewhere on these pages, I documented the saga that took nearly 3 years before I now can boast of having a working TT101, thanks finally to JP Jones.  It's a great table, no doubt.  It's numero uno in my second system.  The Mk3 and L07D hold sway in my primary system, but guess which system I listen to most of the time; yes, the secondary one. The timing is nothing short of immaculate. and that, after all, is the main thing that a turntable has to do well.  Beyond that, it's all about mass and damping.

I think you can find a working unit for around $1000, give or take.  And thanks to the existence of JP, you can probably buy a broken one with some degree of confidence that he can fix the electronics. (Missing parts, damaged or  burnt out motor, no no.)

I doubt JP wants to do a cosmetic restoration of a TT101.  First, his main passion is the SP10 Mk3, for which he has re-created the vital chip (MN6042, I think) using discrete components, with specs superior to the original.  (I bought one, but I still need to have JP install it.  Since I espouse the "if it's not broken, don't fix it" approach, I am procrastinating.)  Second, his expertise is in the electronics.  I would focus him on what he does superbly well, including calibration of the drive system. Even if your DD is ostensibly "working" fine, there is a chance it could be better, more torque, more accurate servo action, if properly calibrated.  JP told me that many DD's sent to him in working order are not in fact operating up to par because of poor or no calibration. (This included my TT101, which besides having a crack in the PCB was also not well calibrated.)  If you re-cap your vintage DD, the next step is probably also to re-calibrate it. (I am not saying that JP is the only person on earth who can do that.  Thuchan evidently found some expertise in Germany, for one example.)

Chakster, The story of my TT101 cost-wise is perhaps more encouraging than Halcro's story.  Mine was on eBay as part of a QL10 ensemble, which is a TT101 set into the top line Victor plinth and bearing a Victor UA7045 tonearm. The seller was honest enough to admit that the turntable was not working.  I was willing to pay no more than $600 for it, on the premise that the tonearm alone is worth about that much.  To my surprise, I won the auction at that price.  Moreover, all pieces are in mint condition.  I now think that the crack in the PCB which was causing the intermittent issues probably was there when the unit left the factory.  Thus my TT101 probably saw very little use over its lifetime.  

I use my TT101 in the QL10 plinth after heavy modifications to the plinth, including the addition of mass and damping, using aluminum slabs bolted to the underside, and replacement of the MDF tonearm board with a custom-machined, massive, aluminum mount.  I'm running a Fidelity Research FR64S in a B60 base mounted into the alu arm board.  I have a slate plinth, originally made for my Denon DP80, but the hole for the DP80 is just a little bit too big or too small for the TT101.  I'm quite happy with what I've got, anyway.

I don't want to encourage JP to raise his prices, but his services are VERY reasonable, especially considering the fact that they are vital to our DD lovers group, as Halcro stated.

Chakster, You asked about testing a TT101 by running it continuously. One guy who put himself out there as a DD repair expert took my TT101, plugged it in at his shop (or so he told me) and ran it for two weeks, with no issues.  He then sent it back to me with the notation that it was not broken.  Fact is, my problem was always intermittent.  I had provided him with a detailed description of the problem, including the fact that it was intermittent, a priori, both verbally on the phone and in the context of a note that I enclosed with the turntable when I shipped it to him.  But like many smug auto mechanics, and some doctors (I am embarrassed to say), he did not pay any attention to the information he was given. Needless to say, fresh out of the box from his shop and installed into my system, the problem was immediately evident once again.  (For a while, my TT101 would work in our kitchen, where there is no audio system; I would then bring it to the basement to use in my secondary system, and down there, it would crash.  We entertained thoughts of a weird glitch on the AC line in the basement, during that phase.) So, no, I don't necessarily assume that running the turntable for months on end is either a good idea or proof of its flawless performance.  The ever kind and patient Bill Thalmann also could not make my TT101 fail in his shop on his workbench, which precluded his solving the problem.  But Bill does pay attention to what customers tell him, and he has a sense of humor.  By the time I found JP and sent it off to NYC, the "intermittent" problem had become much more constant.  Which actually helped JP to find the occult fracture in my "fragile" PCB.

(Problem was as follows: TT101 would start and go to 33.33 on the tach. Within a minute or less, it would then start to hunt for speed, showing 33.34, then 33.32.  Shortly thereafter, it would stall out; the tach would go blank, and the platter would coast to a halt. The electronic brake would not activate.  In about a minute, you could start it up again, and it would go through the same sequence.)

Chak, Your symptom sounds a bit different from mine, although maybe close enough to have the same cause.  As I wrote somewhere here, my TT101 would start up fine and go to correct speed, but it would very soon thereafter start to "hunt"; the tach would show 33.32, then 33.34, etc. Very shortly after that, the tach would go dark except for the decimal point, and the platter would coast to a halt.  This whole process from start to stall never took more than 2 minutes, tops.

Like JP says, in "HOLD" mode, the tach stays blank until it sees the set speed; then it displays.  Thus it is not abnormal to have a short time delay before the tach lights up, but at that moment, it should show the correct set speed.  In RUN mode, it counts up from zero to set speed, visually from the moment you press the button, so there is no delay in that mode.

Don't give up.  We are not living dangerously, just frustratingly.

Chak, I am not sure what you are saying above, but in any case, my TT101 never went to Germany.  In fact, Thuchan did not buy his TT101 until well after mine had been repaired by JP.  Bill Thalmann had a shot at repairing mine, but it would not misbehave at any time in Bill's shop.  I left it with him twice, in fact.  That was another weird aspect of the problem.  As mentioned elsewhere, it would often work well in our kitchen but not in our basement (where I have a second system that now is driven by the TT101, alternating with my Lenco).  In retrospect, we can hypothesize that the fracture in the PCB tracing was causing an intermittent short which resulted in an intermittent problem that could come and go in relation to moving the turntable from place to place.  Trucking it in my car on the DC beltway over to Bill's shop was good for it on the way out and bad for it on the way back to my house.  (Tongue in cheek, of course.) I still have great faith in Bill.

My other point would be that re-soldering all the joints did not cure the problem, because it was basically caused by a fracture in the PCB, cutting across a tracing on the PCB.  JP mentioned his wider experience with the fragility of the PCBs.  So, one might consider going over the PCB with a magnifying glass. Even when JP told me where to look, after he repaired mine, I could not easily see the fault or his repair of it.

Sorry, Chakster.
Evidently my memory of the chronology of events is faulty.  Your quote of my old post suggests that Thuchan's TT101 was up and running before mine.  Otherwise, I would not have been "thinking hard" about sending my own TT101 to Germany, back then.  However, I never did send it to Germany, because I (subsequently) found JP in NYC.  Thanks for setting me straight.

By any chance, do you know the date of that post you quoted?

Sorry, Chakster.
Evidently my memory of the chronology of events is faulty.  Your quote of my old post suggests that Thuchan's TT101 was up and running before mine.  Otherwise, I would not have been "thinking hard" about sending my own TT101 to Germany, back then.  However, I never did send it to Germany, because I (subsequently) found JP in NYC.  Thanks for setting me straight.

By any chance, do you know the date of that post you quoted?

All I can say is, beware of a dealer who claims to be a "good repairer" of all JVC turntables.  That does not necessarily mean he can decipher a TT101.  On one of my misadventures, I sent my TT101 to a guy in southern New Jersey who claimed over the phone that fixing it would be no problem at all.  That didn't work out well, but he is well regarded as a service center for routine problems.

Best-groove, You're right.  Sorry for my negativity.  

I believe this is the second time that someone has cited that article in Audiocircle only to be reminded that all the principles are right here on this thread.  I am the guy who gave Thuchan (aka Eckart) the chip for his TT101.  I gave him two, in fact, because up to that time I had no idea whether the ones I bought from Hong Kong would actually work. (They look correct, but who knew???)  Sadly, I do not have an inexhaustible supply, and I prefer to keep a few for my own TT101.  However, the good news is that you too can purchase the chip from Hong Kong.  I think the part number is "SC3042A", but do not take my word for it; the part number is engraved on the black surface of the top of the chip.  If you need one, search for that part on Alibaba, and you will soon have so many offers to sell that you won't know what vendor to choose.  I chose the one who had the best command of English.  Those vendors never give up.  Even 5 years or so later I still get emails from some of them. By the way, my TT101 did not need a new regulator chip. It's still running on the original.

By the way, there are several other chips in the TT101.  I don't know what they do.

Peter is on to something.  Look under the bottom of the bearing well. There you will see a large slot-head screw.  The screw has the bearing thrust plate built into it and adjusts the spindle up and down, but if the screw is in too far (clockwise motion), the rotor will rub on the stator. (Because the spindle is also part of the rotor of the motor which moves with it.) Likewise, if the screw is out too far (counter-clockwise), the platter begins to rub on the escutcheon.  There is a very small sweet spot where the platter will turn freely.  If you're lucky, maladjustment of that screw is hanging up the platter so it cannot rotate freely.  What I did finally with my TT101 is to take a Greenlee hole punch and punch out a small hole in the center of the bottom of the shield that forms the outer shell of the chassis.  So now I can just take a short-handled screw driver and adjust that screw if needed, without disassembly.  Of course, once I created the access hole, I have never again needed to adjust the screw.

Trust that UPS will find a way to deny any culpability at all.  Zero. It's simply NEVER their fault.

Dear Lohanimal, I am very sorry for your predicament with UPS.  Apparently the same snot nose kid who waited on me in Bethesda, Maryland, before eventually telling me that UPS was not going to admit responsibility for destroying a piece of slate I sent to the West Coast, has now left the USA in order to mistreat citizens in other countries.  It's what they do.  By the way, I showed him photos of the slate as it was packed in wood crate when it was presented to UPS for shipping, and then as it arrived in California, in several pieces.  Like your guy, he was unimpressed.

Aigenga, Do you mean to say that you will never want to play an LP again, even to generate a digital file of it?  Seems that the latter option might cause you to want to hang on to your rig.  But of course it's your decision to make.

I feel you, but I am far too lazy to make the effort to transfer my approximately 2500 LPs to digital, even if I wanted badly to do so, which I don't.  I have a very good CDP (Ayre C5Xe-mp), and I leave it at that.  My CD/SACD collection is much smaller than my LP collection.

Agreed.  Your listening impressions of the TT101 as compared to the DP80, both with your upgrades and plinth, would be very informative.

Henry, I thought, "Bob's your uncle."  Whistling Dixie is not such a good idea right now.

Henry (Halcro) mentions the $30,000-VPI DD turntable, which seems to have come and perhaps gone from the market, like a will o' the wisp.  I am guessing that VPI will still build one for a buyer, but they have certainly stopped flogging it, preferring instead to hammer away at the middle of the market in terms of cost, with their latest belt drives.  Maybe they are selling them to wealthy Asians and Russian oligarchs.  Has anyone here actually seen the VPI DD, and if so, have you listened to it in a good system?  Better yet, have you been able to compare it to one of our beloved vintage DD turntables?  Henry implies that a well done TT101 would be on an equal footing with the VPI, which made me wonder.  Another such item is the Monaco Grand Prix.

Thanks, Peter, but I notice you gracefully declined to say how the VPI compares to one of your restored DP100 or DP80 Denons.  I read the S'phile review of the VPI by Fremer.  He publishes real data these days on speed stability.  I also recall that the DP80 owners manual included a graph showing speed vs time for the DP80, but not the max and min variations that contribute to the average speed curve.  I've wondered how the DP80 and of course some others would look on Fremer's instruments.  (Is he just using a Feickert computer program, or what?)

From comparing many different DD turntables in my own system(s), I am very persuaded of the inherent superiority, or at least the desireability, of coreless motors.  That's only an opinion.  Although the DPs have an exceptionally good 3-phase synchronous motor, it is not a coreless type, so far as I know. On that basis, I would be surprised if the VPI (which also has a coreless motor, probably one that is superior to any of the coreless motors with which I have listening experience) was not as good sounding.  But audio is like that; one must be careful predicting what one will hear based on how a product is made.

Nandric wins "Funniest Post" award. The rest of you can hand in your computers.
Henry, are you confirming that the data posted by Fremer come from the Feickert tools? I am sure he does not keep it a secret, but I cannot find where he says what instruments he uses. If the cost is reasonable, I would love to purchase the equipment just to test my 5 turntables.

Results for a DD will be heavily dependent upon the accuracy of calibration of the particular unit under test. That’s where guys like JP come into the picture. JP’s homebuilt chip for the Mk3 is more accurate than the original chip, but at a level where we are not sure it could be heard (perhaps also "surpassing [the accuracy of] measuring instruments"). Or maybe JP has done a listening test by now that does reveal differences. In other words, if one sample of a Mk3 is less accurate than one sample of a TT101, it proves nothing unless we know the state of tune of those two units.

I did run my Mk3 with a borrowed Timeline, and it was spot on at about 10 feet projection, but with "only" one tonearm and cartridge playing music. The friend who lent it to me owns a very expensive belt-drive. When he demonstrated the Timeline to me on his system, he literally had to get up and run to the motor controller about every 5 minutes so as to prevent the reflection from marching all around the room. As it was, it marched about 2-3 feet in minutes. He subsequently complained about the speed problem to the manufacturer who promptly supplied him with an "upgrade" to the motor controller.  In fairness, that did help the speed problem.  I think the Timeline is over-rated and overpriced, nevertheless.

Peter, I use the Roadrunner/Eagle to control my Lenco.  It is comforting to see the RR display 33.333, every once in a while.  In practice, the speed takes about 5 minutes to stabilize usually around 33.3, then 33.33, then flirting with 33.333, maybe after 10 minutes in.  I think the bearing lubricant may be warming up during this early time.  But I don't understand why you would want to "control" the Denon DP80 or the DN308 motor with the RR feeding back to the Eagle.  Wouldn't you want to leave that in the hands of the built-in feedback mechanism which is making constant readings (not just once per revolution) off the tape that is attached to the inner circumference of the platter? You could certainly use the RR for a numerical readout of speed without having it control the motor; maybe that is what you are doing.  (I don't think anyone would hear a problem with 33.334 vs 33.333.  I don't even hear any significant difference between 33.3XX and 33.333. (Talking with respect to the Lenco.)

Chakster, I am of the belief that a cylindrical plinth that has a diameter minimally greater than that of the platter is optimal, regardless of drive system.  I think our conventional rectangular plinths with a large surface area beyond the platter area add a subtle coloration that is appreciated when one compares the sound to the cylindrical type, which sounds most "open" to me, for want of better words to describe it.  But I do not associate OMA with originating the idea, at all.  Nottingham and Verdier and also Galibier, Teres, Redpoint, etc, beat them to it.

The OMA copy of the Verdier idea, is, like the Verdier, a can of worms.  Center of gravity is way way too high, for one thing.  Springy footers plus rotating mass raised high above = instability.  IMO, of course.

Dear best-groove,
What do you mean when you say the "engine started to lose laps inexorably"?  It would help if you can make the problem more understandable.  However, I also think that it would be impossible for any of us to say categorically what is your problem, because the TT101 is such a complex beast.  You need the services of a good technician who can assess the unit on his own bench top.

There are known issues to be aware of:  
leaky, old capacitors (replace all electrolytic capacitors with new),
bad control chip (possible but appears to be rare in actual experience),
bad solder joints, especially around the eyelets (very high on the list),
fractures in the PCB (mine and at least one other, but maybe not so common).

I didn't mention potential problems with ANY old turntable, such as issues with the bearing and spindle shaft.

Also, best-groove, it is probable that your turntable needs calibration. As I understand it, calibration involves equalizing the impulses derived in each of the 3 phases of the motor cycle.  JP can elaborate if he is around.

I still don't understand what you are observing.  Let me guess: the turntable comes up to speed and works normally for "2-3-5-7 hours" and then...  Here is where I lose you; does the motor stop driving the platter and then does the platter coast to a halt, or what?  In failure mode, do all the lights go out, or not? In your second one-sentence paragraph, are you now saying that the problem was solved by re-soldering some joints?  

I will say this: If you acquire a vintage DD turntable that has not been serviced in a decade or more, the FIRST thing to do is to replace all the electrolytic capacitors.  I say this, because leaky capacitors can cause damage to other vital active components that are not so easy to replace, and this can happen the moment you apply AC power.  The term "leaky" refers not only to the fact that old electrolytics can leak fluids but also to the fact that old electrolytics can "leak" DC voltage.  A functioning capacitor often is used to block DC from entering parts of a circuit where DC can otherwise damage associated components.

Replacing the electrolytics as a last resort is, as we say in English idiom, locking the barn door after the horse has escaped.