Vintage DD turntables. Are we living dangerously?

Lew,
I think the Victor TT-101 originally sold for 165,000 Yen whereas the TT-81 sold for 75,000 Yen?
Big difference but the complexity of all the variable 'pitch' options plus the dual bi-directional servo sensors all contribute as well as the motor difference.

Great thread - I concur that the TT101 is a great table and I had the same concerns as Halcro, so I have a back up for spares

I have a tech here in Ottawa who is from Vietnam and specializes in servicing vintage Japanese gear, his workshop is floor to ceiling with vintage "junk". He seems to be able to fix anything I have thrown at him, including by backup 101 when it started to behave badly. So I am on the page that we can get by for a few more years yet.

On another note, I bought a heavy lead plinth for the TT101 from Tommy Cheung specially drilled for the table and accommodates 2 arms. Makes a big difference, but admittedly I have not tried the table nude. I found the best mats are the micro seiki cu-180 closely followed by the SAEC SS300.
My reference table is my Seiki sx8000 and the 101 is very close, such that sometimes I muse on selling the big micro.

My observation on coreless motors in direct drive turntables is that there are physical traits, at least the ones I owned and saw in pictures. Please keep in mind that I am not an motor engineer so my observation does not define what a coreless motor is.

(1) The most obvious is that the rotor magnet is always above the stator coils and there's small gap between magnet and coils. (Less "grip" on the coils and, not surprisingly, less torque.)

(2) The series of coils on the stator are ironless. (Helps to simplify its construction)

(3) Lower torque than typical core motor. (Not as dynamic sounding or less "jump" factor.)

(4) Many, not all, rotate smoothly even without the platter so they do not rely on the inertia of the platter mass like other DD motor. (This is an indication of its fluid sound.)

Here are some examples and observe the physical similarities.

JVC TT-101

Sony PS-X7

Sansui XRQ7

JVC QL-A2

Kenwood L-07D

Kenwood L-07D

Pioneer PL-50L II

Sony PS-X6

Kenwood KD770D

Dual 701

Brinkmann Bardo

Halco: "Doesn't it seem odd....if a coreless DC motor produces no cogging and sounds so 'fluid', relaxed and unfazed.....that a manufacturer would be foolish to even contemplate an alternative design?"

Coreless motors were utilized in most later models of many brands, especially in the late 70's and early 80's. Pioneer shifted to coreless motors in almost all their later models. Kenwood did the same starting with KD-770D and KD-990 -- I don't believe the KD-500, a model in the early years, uses a coreless motor. Sony used their version of the coreless motor called BSL (Brush & Slot Less) quite early in all their "PS-X" series. With the exception of Technics and Denon, almost all Japanese manufacturers shifted to using coreless motors in the late 70s and ealy 80's. Denon stubbornly stuck to their AC induction motor all the way through the 70s and 80s.

The earliest use of coreless in DD table is not even in Japan but in Germany. Dual used the earliest motors in the 701 in 1973, few years before the use of quartz lock drive. The motor model is EDS-1000.

Back to Halco's question. Many Japanese manufacturers did ask that question and they decided on the coreless motor. If given another decade to further develop motor in DD technology, I believe almost all would use coreless motor, given the trajectory of the trend in Japan. But CD ruined all of that. :(

_____

Hiho, The information I have been able to gather suggests that it is simply more difficult to get torque out of a coreless motor than out of a similarly sized cored motor because the coreless motors tend to trap heat and thus overheat, and overheating is lethal to them. (The iron or steel core in a cored motor also makes a good heat sink, so motors intended for heavy duty and continuous operation tend not to be coreless.) However, the Pioneer Exclusive P3 (coreless) motor is second only to the Technics SP10 Mk3 motor in terms of torque among the TOTL Japanese DD's, as far as I can find out. (Perhaps the Denon DP100 motor develops more torque than that of the P3; don't know. It's as big as a coffee can, so I would not be surprised.) If you read about Kenwood's thinking in the design of the L07D, they actually did not favor high torque in principle. So they were not concerned with competing in that "horsepower" race. Also, the drive system (the implementation of the servo mechanism, use of a quartz reference, handling of the AC and/or DC, speed of the sensor mechanisms, etc) are also determinants of the success of a DD design; cored motors can be made to work just fine, IMO. The fact that Denon and Technics stuck with cored motors does not necessarily mean they were "stubborn". However, like you, I am not a motor engineer. Motors and how they work, what makes one better than another for this or that application, are fascinating and complex subjects.

Apropos of that, you cite the Brinkmann Bardo for using a coreless motor, and I did too in one of my earlier posts, but does anyone know about the Grand Prix Monaco, the NVS, or the Teres Certus? For that matter, what about the Brinnkmann Oasis?

Lewm: "The fact that Denon and Technics stuck with cored motors does not necessarily mean they were "stubborn"."

Sorry, I did not mean to imply anything negative about Denon and Technics not using coreless motor. Perhaps the word "stubborn" was poorly chosen but was really intended to mean they did not follow the trend as they probably felt their DD development were mature enough to withstand the shifting trend. I know I like the sound of several Denon turntables, coreless or not. I know you like your DP-80. As for Technics, let me just say I am off the bandwagon.... but that's a different topic.

Lewm: "does anyone know about the Grand Prix Monaco, the NVS, or the Teres Certus? For that matter, what about the Brinnkmann Oasis?"

The only info on the Monaco I can find is from 6moons.com that says "The finalized Monaco turntable runs off a 5-8V 12-pole DC motor inside the main chassis." No indication that is coreless or not.

No idea what the NVS uses.

The Teres Certus uses a CORE motor from pictures I have seen of its innards.

The Brinkmann Oasis is the same as the Bardo, except it has a plinth. The Bardo is the stripped down version of the Oasis for a lower price.

Motors are fascinating indeed!

_____

Lewm: "If you read about Kenwood's thinking in the design of the L07D, they actually did not favor high torque in principle. So they were not concerned with competing in that "horsepower" race."

I think I agree with that thinking and from the sound of many DD turntables with coreless motors it only confirms that. I much rather have a smoother rotation than just high torque. Judging by the reviews of the Brinkmann Bardo, a low torque design, they are onto something and the impression is that the Bardo does not have the stereotypical sterile sound related to DD tables.

_____

Ah Radicalsteve,
The luxury of two TT-101s ?:^)
Interesting comments on the two metal mats.
I assume you are thus using no damping on the aluminium platter?
Can you describe the differences in sound you hear with these mats over the standard rubber?
Would be appreciated?

Thanks for those images Hiho...and all the informative comments.
Regards
Henry

Oops, the posted image of the PS-X7 motor was supposed to be PS-X9, Sony's flagship. Sorry for the error.

______

Hiho, In some magazine or on the internet, I saw a photo of the Bardo motor with its coils exposed. It is striking how much the whole construction resembles either one of the L07D motors you showed in your photos. Makes you wonder whether Brinkmann intentionally took a page from that book.

Reference to "12 pole" in the description of the Monaco motor should tell us that it is a 12-pole motor, not coreless, if I my understanding of the jargon is correct. But I read in one of the original reviews that the motor is a very advanced modern space age design specifically aimed at eliminating cogging. I also read on the NVS website that they have eschewed the use of a servo system; I hope I am re-stating it correctly, but as I recall they make the motor operate against a specified drag, in order to keep speed stable. Much like the eddy current brake used in the Garrard 301/401.

On Technics. My early impression of my SP10 Mk3 suggests it lives up to the hype.

Has anyone here (hello, Shane) been listening to an Exclusive P3? I'd like to get a better feel for that thing.

Lewm, I think the Bardo and L07D both took a page from the granddaddy of coreless motor, EDS-1000 from Dual 701.

Brinkmann Bardo stator coils

Kenwood L07D stator coils

Dual 701 stator coils

Lewm: "On Technics. My early impression of my SP10 Mk3 suggests it lives up to the hype."

That's good to know but unfortunately I can't afford it. I heard all the models below the Mk3 and let's just say I have moved on. I'll say this: when it comes to bass dynamics and tightness, the SP10mk2 reigns supreme so I suppose the Mk3 is even better? I do miss playing my punk records on the Technics though.

______

Way cool! Did not know about the Dual. Perhaps I should have gone to R�MAF after all to hunt down each of the modern DD's that we know so little about.

I take it you were dissatisfied with your Mk2 on other grounds besides "bass dynamics and tightness", One big diff between my Mk2 and Mk3 is that I made a better more sophisticated plinth for the Mk3. The Mk2 was all slate. The Mk3 plinth is equal parts slate and cherry wood and weighs around 90 lbs. I found that the addition of the stiff hardwood dampens the slate, whereas the slate is very good for channeling energy away from the Mk3 chassis. Anyway, the Mk3 plinth is very neutral. The Mk3 itself imparts a little more energy than the Mk2 and has very low coloration, if any. However, I thought the Mk2 in slate was very fine and could have lived with it. I firmly believe there is such a thing as "good enough". After good enough, the rest is a hobby.

The closest to the Dual 701 motor design is the later version of the Kenwood L07D motor because, like the Dual, it has two layers of coils except Kenwood made them in star shape to avoid patent infringement. Compare to the older version I think I would prefer the later one because the magnetic field is symmetrical, hence, I assume, more balanced rotation. If people who own both of them, I would like to hear about the sonic difference. Which version do you have, Lewm?

Lewm: "I firmly believe there is such a thing as "good enough". After good enough, the rest is a hobby."

Great quote!

_______

Far as I know, the motor with the symmetrically arranged coils is indicative of a second generation L07D. There are photos of such a tt on the LO7D website hosted by Howard Stern, who serviced both of my L07Ds. But in real life, I have never seen a second generation LO7D for sale or known one to be in the hands of an end-user. (It differs from the first generation type in other ways besides the motor structure; the tonearm rest and the adjustable support feet were also built differently, and there may be some differences in the electronics, or not.) I suppose if you canvas the LO7D email group, you might find one. Last year there might have been one for sale on the Hifido website. Which is a long-winded way of saying that my L07D(s) (both of them) are the much more common first generation type with the assymetrical coils. There has to be a reason why Kenwood chose to build it that way, but I cannot imagine it. Do you think it was to avoid infringing on Dual's patent? Note that the Bardo coils are not symmetrically placed around the spindle, either.

The topic about the Dual motor and later generation of coreless motors in L07D and Bardo has been covered by an Audiogon member who is also an aerospace engineer, Wjsamx in a thread about the Brinkmann Bardo from last year, as you might remember reading it.

Here's what he had to say:

06-15-10: Wjsamx
Dual came out with the first and only EDS (electro-dynamic suspension) DD TT motor, for which they've never gotten any credit. Being an aerospace engineer, I can tell you this type is the only true magnetic direct drive motor. The Technics platter is nothing more than a magnet that sits in a rotor, is configured horizontally, which essentially becomes a standard motor stabilized by tach signals and OCD type electronics. The Technics motor suffers from pole jerking, magnetic drag, hysteresis, and requires a very large amount of power. The Dual EDS motor works like a modern magnetic railway. When the magnet is between 2 poles, the powers of the 2 poles are proportionate. In other words, if the magnet is dead center between the 2 poles, both poles will have 50% power, but if 80% of the magnet is over one pole and 20% of the other, the power is split 80/20 and so on in a linear fashion. It only requires 50 milliwatts of power to operate, since opposing magnets are the major force behind its propulsion. There is no need for quartz control. The hall sensors monitor the strength of the magnetic field within the system and hold stable regardless of fluctuating line voltage. A heavy platter is not required, and the technology of EDS actually allows the platter to (microscopically) levitate when it is operating, significantly reducing typical negative spindle and bearing contributions. This motor is dead silent. Unfortunately this EDS motor never received recognition and was very expensive for Dual to manufacture. At one time, Dual had 3000+ employees and completely made 100% of their own parts and motors in-house. To compete and save money, they "cheapened" newer motors and went along with the crowd of quartz control. BTW, the motor in the Dual CS5000 is an EDS type motor, although it provided belt drive. It seems that the Brinkmann DD motor is nothing more than a new type of Technics DD motor. The fact that the coils are not totally equidistant means it's "pushing" and "braking" in an un-uniform manner favoring one side. I believe they bandaid and hide issues by the use of a heavy platter. I'm in no way discrediting other manufacturer’s contributions to DD TT technology. Technics may have been the first to the commercial market with DD, but Thorens developed and patented the first DD motor way back in 1929. With respect to the discussion of "magnetic direct drive", Dual was the pioneer and implementer of this type of DD motor. Technics and other manufacturers have nothing to do with this type of motor as their DD motors act more like stepper motors. So the correct timeline is Thorens invented the first DD motor, Technics was the first to market the DD TT, and Dual was the first, last, and only to invent and market the EDS magnetic DD motor for use in turntables.

06-16-10: Wjsamx
Dear Lewm, There are 2 different motor designs for the K07D. The initial Kenwood motor that looks similar to the Brinkmann (and the Dual) but with 6 red coils was a patent infringement on the earlier Dual design. This is why Kenwood had to later change the design to the green star shaped coils, which you can see are not asymmetrical. Kenwood and other Japanese manufacturers thought they could get around the patent issue by using a different number of coils, placing them asymmetrical, compensating with electronics, and changing the specs. It was very common practice, and still is today, for manufacturers to purchase competitors products, completely disassemble them, study the design, and attempt to deviate enough in their own design to try and beat any patents. The Dual EDS motor had 8 double field coils in symmetry with a special conductor plate below it. The magnet was made of barium ferrite and had 8 pole symmetrical magnetization. The electronics in this system were so minimal compared to others that it fit on a round circuit board the same diameter as the bottom of the motor (5 inches). The motor was one complete assembly including the electronics. The platter just fit on top of it. In regards to the Brinkmann motor, I can't understand the reason for the odd placement of the coils. One would think there is a dead spot of power in its rotation which is why I believe its concept is to push and brake. The motor seems by design to only pulse power to the rotation as needed. Once the heavy platter is at speed, the energy within its mass is creating the needed centrifugal force for rotation. The tach feedback will sense speed deviation and only micro-pulse the "motor" as necessary to keep the platter steady at speed, like cruise control. Judging by the size of the motor, it's not meant to "direct drive", it is just too small and weak. It's really a "soft drive" system. Weak micro-pulses of "magnetic" power to the platter would certainly not create a large impact on such a heavy platter, thus eliminating any cogging effect. I do like it's simplicity, and it must obviously work, although they don't advertise any specific specs other than it takes 12 seconds for the platter to reach speed. The white pages on the Brinkmann motor suggest they are using a non-standard 22.5 degree angle on the coils with an 8 pole magnet, claiming that the overlapping magnetic fields reduce cogging. Isn't it strange that this Brinkman motor is very similar to the Dual EDS motor, which has 8 coils instead of 4, both use the coils at a 22.5 degree angle, both have hall sensors, and both have 8 pole magnets. I guess the Dual EDS motor patent has long expired. Essentially, one can get a Dual EDS motor, drop it in a plith, and have a Brinkmann for about $200 + tonearm. It might be ugly, but it won't cost 8 grand. Honestly, and with sarcasm aside, if I were looking for a new TT, I'd consider the Bardo, but only after having a demo.

Have a look at Dual EDS motor:
Exploding view of motor - - - & - - - Cutaway view of motor

Brinkmann white pages:
Brinkmann whitepaper in PDF file

A lot to absorb but fascinating stuff to read about motors. :)


______

Hiho, His second post was in response to something I must have written, since he is addressing me. Yet I have no recollection of ever reading this treatise before. Also, he talks about "poles" in coreless motors, so this means I am full of baloney (to put it nicely) when I said that the Teres (was it?) motor cannot be coreless if it has "12 poles". I have to do more reading on this subject because obviously I am not qualified to have any opinion. Now, where can I buy a Dual 5000CS? That would be a great motor for my Lenco.

Hi Lewm /all

yes, still listening to the Exclusive P3, as is T-Bone and Jaspert.

Specs wise, they are faultless and a lot better than the tt-101. The SP10 mk3 has better start up torque to the P3, yet the both the L-O7D and P3 have better s/n ratio.

sound wise, fast and smooth.

Over the weekend I played some Grant Green on the P3, then over to the TW Acustik AC-3. the vistor thought the TW was playing slow. It wasn't, it was just the P3 starts and stops like a F1 car. the Lyra cart on the p3 obviously helped v the dyna which is a little slower.

The Exclusive was the best selling high end table in Japan. No doubt that was a combination of performance and something that looks awesome without any drawbacks.

cheers

Since the thread topic is about repairing turntables. I would like to share an amazing audio repair site that shows many hi-rez repair pictures. Totally audio porn for the gearheads like me. And I am sure of you already knew about this site.

Amp8.com turntable repairs

Micro-Seiki repairs

Technics/Panasonic repairs

Kenwood repairs (including three L-07D !!!)

Denon repairs

JVC/Victor repairs

Sony repairs

==============================

For Lewm, here are couple hi-rez pictures of the stator coils from Kenwood L-07D

Red round coils

Green star coils

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Thanks, Downunder. I hardly think that the speed and precision of the P3 is due to its fast start. One is not listening at the start. Yet there does seem to be a consensus that a sense of "speed" or pace or whatever like that is superior for most direct drives vs most belt drives. For one thing, this may have to do with belt creep or belt stretch; no matter how sophisticated is the motor drive, it's work is applied to the platter via that belt.

Hiho, Great photos of the LO7D motor coils but the photos at the website only get one to an index page and for me the URL goes dead at that point. Not to worry. I am wondering whether the guy you referenced is correct when he implied that the assymetric placement of the coils on the original LO7D motor and on the Bardo motor would result in aberrant drive from the motor. I think the field created by the coils would average itself out. (I also think there would be a limit to the odd spacing where once reached the field would no longer be able to average itself out and would result in a dead spot on each rotation.) But this is just idle speculation and curiosity.

He said or inferred that the Dual CS5000 would have an EDS coreless motor. But based on what I read at the Dual history website, that may not be the case. Just what models of Dual DO in fact have the EDS motor. I think their idler drive tts, like the 1019, have induction motors (a la my Lenco).

Lewm, I was hoping you would click on the "Kenwood repairs (including three L-07D !!) prompt and click on any one of the L-07D buttons. (Obviously I am a finger clicking happy internet search fiend!) Check out all those dozens of hi-rez images of repair parts. Amazing clarity.

Lewm: "I think the field created by the coils would average itself out. (I also think there would be a limit to the odd spacing where once reached the field would no longer be able to average itself out and would result in a dead spot on each rotation.)"

He did mention that the Bardo works in a "soft drive" approach and, perhaps the L-07D might also work in similar way:

Wjsamx: "In regards to the Brinkmann motor, I can't understand the reason for the odd placement of the coils. One would think there is a dead spot of power in its rotation which is why I believe its concept is to push and brake. The motor seems by design to only pulse power to the rotation as needed. Once the heavy platter is at speed, the energy within its mass is creating the needed centrifugal force for rotation. The tach feedback will sense speed deviation and only micro-pulse the "motor" as necessary to keep the platter steady at speed, like cruise control. Judging by the size of the motor, it's not meant to "direct drive", it is just too small and weak. It's really a "soft drive" system. Weak micro-pulses of "magnetic" power to the platter would certainly not create a large impact on such a heavy platter, thus eliminating any cogging effect."

It reminds me of the belt-drive school of using weak motor to nudge the heavy platter to keep it up to speed and let inertia and flywheel effect take over. After all, Brinkmann is a mostly famous for the belt-drive turntables so they might be approaching DD with a BD mentality. Hey, if it gets the job done, I have no problem with that.

If it sounds good to you then that's what matters. I have some JVC motor with asymmetrical coil layout and they sounds very smooth to me. But I have to say the Dual 701 motor has a harmonic richness I don't hear from most DD tables and whether that has to do with its symmetrical coil arrangement or not, I have no idea.

Lewm: "He said or inferred that the Dual CS5000 would have an EDS coreless motor. But based on what I read at the Dual history website, that may not be the case. Just what models of Dual DO in fact have the EDS motor."

On the Dual Reference site, it does say the motor is "EDS 5000 System." It's a belt drive turntable so I don't know if the motor is usable for idler drive purpose or not. The most famous EDS motors are obviously in their two DD tables, 701 and 721.

_______

Yes, the direct-drive school does seem to have two camps, high torque motor/light platter vs low torque motor/heavy platter. And yes I think the LO7D is more in the latter camp, certainly compared to Technics stuff. There is an analogy in belt drive turntables too. Notts and Walker (to name two of many) favor weak motor/gigantic platter. SME and (argghh I can't remember the name, begins with an "A") would be in the light platter/powerful motor school.

The only guy I know for sure who would understand this stuff and could explain it to us is Mark Kelly, but he is preoccupied with other things at the mo'.

Avid. That's the name I was trying to think of. Nice stuff. Light-ish platters/high torque motors.

Using a stethescope (is that sick or what?) I can hear a hum that sounds like the transformer to me: it only sounds when the power is on whether or not the platter is spinning. It makes me think about pulling the power supply out of the tt and moving it into a separate box. Has anyone done this? If there aren't many different feeds at perhaps different voltages then I would think it could be done without spending a fortune. Am I dreaming?

Hi Aigenga,
Strange you should mention stethoscope?........I just bought one last week and have been madly scouring all my shelf positions, motors, platters,,tonearm supports and plinth.
I have absolutely no motor hum whatsoever from the TT-101.....and that's placing the stethoscope on the metal motor surrounds, the aluminium control fascia and even the platter( with the motor on but the platter not spinning).
I'm surprised your Techi didn't check out the working performance after changing out the caps as you said there was noise in the bearings as well?
Something is amiss. Hope you find it?

Aigenga,
Does your TT-101 have the grounding cable attached to it?

Halcro,
I'm glad to hear that someone else is crazy enough to buy a stethescope and go looking for trouble. I hadn't thought of it but you are right that the tech should have noticed that the transformer is humming.
The motor now is beautifully silent, and I tried with and without the ground wire attached to the phono pre-amp but no difference.
Today I am going to see if I can rubber mount the transformer. I might need to replace it. But if there is a way to power it via an umbilical cord that would be best. There is a good write up of this at the KAB turntable site and I sent an email to Kevin asking if he could do it.
Gary

A vibratory hum from the transformer is nothing to worry about, as long as it does not intrude on the listening experience. If you had an amplified hum coming thru the speakers, that is another story, but don't worry about the local mechanical hum. Why yours hums and Henry's does not is possibly only a function of the voltage and/or frequency of the current coming from your wall socket vs Henry's. (Don't know the voltage/frequency in Australia.)

Henry, are you using that stethoscope to identify nodes in your shelf? As a doctor, of course I was born with a stethoscope around my neck, and even though I never use one in my chosen field, I have always owned one or two.

It may be the case that you both wanted as kids to become
Doctor. To compensate you invented this excuse to buy an
stethoscope. I use my to listen to my neighbours. She is
unbelievable beautiful and I am waiting to 'hear' any mistake he may make.

Regards,

Lewm, my thinking is that the vibrating transformer adds to the general hash of noise we live in and that the stylus needs to decode. So, even though I don't hear it specifically, it can't be making things better. Also, the EMF generated by the transformer may be effecting various electronics including the cartridge and again, none for the better.
Gary

As this is a vibration / distortion hobby using a stethescope makes alot of sense to me. Yelling at your cartridge to see if direct sound pressure affects it - now that borders on questionable.

Lew /Gary /Henry – what brand of scope would you recommend. I figure I can also play doctor with my dog if I get bored. Before you reply Nikola - remember they are mans best friend.

Great info on this thread.

I have a question about an SP10 4 lb copper mat I own. Opinions seem divided over the years on whether these heavy mats do any harm to the DD Servo in the longer term with a SP10 MKII or equivalent other brand. Has anyone had any problems using them ?

I haven't used mine much as I actually like the sound from the stock rubber one. But am wondering ?

Cheers Chris

stethoscope. I use my to listen to my neighbours. She is
unbelievable beautiful and I am waiting to 'hear' any mistake he may make.

Ahh Nicola......what would we do without you? :^)
Yes Lew.....stethoscope is good for finding 'nodes' on a shelf however we have to be careful how we interpret these as.....on a wall-hung shelf....the only way to find these are by dynamic loading.......ie tapping.
There is....as far as I know.....no direct correlation between this and air-borne sound transmission?
The TT-101 (like all Japanese-only products) is designed to run on 100 volts.....not 110v as you have in USA. Could that be the cause of Gary's hum?
I have a 240v to 100v step-down transformer between the GPO and the TT-101.

Dear Henry, 'what would we do without you?' This is an easy
question: some will (I hope) laugh less, some will be (I am sure) less annoyed.
BTW the sequence or the order of our actions should be: ask
first and buy there after. However nobody can forbid the other to buy an stethoscope first and ask what to do with this instrument there after.

Regards,

Chris, this is from the manual for my SP-10 Mk2A:

"The quartz phase-locked control system and the DC servo motor with large torque can maintain each rated speed of the turntable even with a load torque of up to 5 kg-cm (4.3 lbs. in.). If 500 tonearms of 2 g. tracking force were placed on a record at the same time the turntable would still maintain each rated speed."

From the way this is stated, I assume it applies to the sum of the weight added on top of the platter. There was an accessory Audio Technica disc stabilizer (vacuum) designed for placement on top of the SP-10 platter (perfect fit after the mat was removed) which I believe weighed 1.4 kg. So mats heavier than the standard rubber mat have been used.

Where to begin?
Dear Gary, Henry makes a VERY good point; if you have plugged your TT101 into the 120V wall outlet, that could very well be what is making your transformer hum. Even though the voltage is only slightly different from 100V, you had best use a step-down transformer. You may eventually damge the TT101, otherwise. They are available on eBay. You only need one that can handle 50W or slightly less.

BUT I am not clear on what you are hearing. In your last post it sounds like you may indeed be hearing hum through your speakers. If so, this is unlikely to be due to the power transformer. Look for another cause. As for EMF, the transformer and turntable motor are emitting EMF no matter whether they are noisy or not. I use a shield on my (coreless) LO7D motor (between the platter and the platter mat, made out of TI Shield available from Michael Percy). There never was any hum problem with LO7D; the shield reduces or removes a kind of gray-ish glare that colored the L07D output. TI Shield blocks both EMI and RFI. If you are hearing only a local mechanical hum directly from the tt, then go back to my first paragraph. If you are already using 100V step-down, then you just have one of those transformers that hums. Try reversing AC polarity; sometimes that helps.

Dear Henry, Of course you have to tap the shelf!!! The node will be at the same place regardless of how you stimulate the shelf to vibrate, so the result achieved by tapping and listening with the stethoscope is always valid. However, I do not think this has much if anything to do with airborne vibrations. This has to do with structure borne vibrations emanating from your environment. Even a wall is not inert, as you know better than I do. Plus there is the issue of micro-seismic activity. And your huge feet clumping around the room as you dance to the music.

When I was a medical student, everyone wanted a Littman stethoscope. But there is at least one other very good brand. I have not only two of my own but the one that belonged to my father, from before WWII. A�nd my wife would lend me hers in a pinch. (That is, if I pinched her.)

Gary AND I should have written "EMI", not "EMF". EMF stands for ElectroMotive Force, which is another term for voltage. EMI stands for ElectroMagnetic Interference, which is undesired low frequency radiation from a transformer or motor. I picked up on Gary's error in my response.

Lewm,
EMI it is. I can only hear the vibration using the stethoscope pressed against the plinth or top plate, not through the speakers. It is faint, not audible with naked ears (at least mine). It doesn't change with a reversal of the plug. What reduces it the most is damping the sheet metal cage on the underside of the table using a squash ball suitably squashed against the shelf.
The table was sold in Los Angeles, CA (it has an import stamp) and is actually part of a QL10. The QL-10 is three separate components: A TT-101 direct-drive turnable, a UA-7045 tonearm and a CL-P1 base board, combined and sold together. On the rear of the plinth is a metal plate showing 120V, 60hz, 23W. I am using a Technics EPA-100 that I had rebuilt by Jim Howard rather than the UA7045 at this time.
I am making inquiries on moving the AC power components into a separate box - I refer you to KAB Electro Acoustics, KAB PS-1200GX as an example of what I would like to do but can't see how I can, but I can have the transformer, etc. moved. And I will if it is reasonable. I am also going to order that TI shield. Thanks for that tip.

Based on your last post, I would not worry one bit about that hum. (Obviously your TT101 was built for 120V.) But if you like to worry, I still would not go to a lot of trouble and expense to move all the electronics out of the tt chassis, if indeed it could be done with the TT101, which as H pointed out is quite complex, and quite a bit more complex than an SL1200.

Do you like the EPA100 significantly more than the UA7045? I always thought those Victor tonearms might be sleepers and have been tempted at times to buy the 12-inch version.

The TI Shield is not going to kill the hum, because the hum is of mechanical not electrical origin, but you might find it benefits the sound and is definitely worth the effort. I ordered a 12 X 12" sheet and cut it in the shape of an LP, so it fits under my tt mat and does not show. For best results, it should be grounded to the tt chassis. If your platter is made of anything conductive, e.g., alu, that should take care of itself. Let me or let us know if the TI Shield cleans up the sound in surprising ways.

Pryso - thx for the info. Thats reassuring

Littman it is Lew Thx. Chris

Mind you, the Littman was preferred by cardiologists, not audiophiles. As I recall, it was quite good for picking up murmurs. But another virtue if you are schlepping it around a hospital all day is that it is very small and light compared to some others that have complex and heavy bells. (The bell is the business end of the scope.)

Lewm, I am mostly playing my high compliance mm carts at this time and the UA7045 is not compatible. I think the 7045 is excellent and would recommend it and by extension the 12" 7082. Also Jim Howard did an excellent job on the EPA100 so it really sings, so I really enjoy it.

I am interested why you think the vibrating transformer is not effecting the oh so sensitive stylus? It seems to me that I need to quiet it anyway I can.
Gary

A soldier has his uniform, an officer my have a sward, the English lawyers have a wig and a doctor has the stethoscope. This is called 'non verbal communication' but
somehow it seems to work. Such that Ataturk wanted to raise his country into the Western civilisation by ordering that every Turk was obligatory to wear a hat. According to
the same logic the only thing one need to do is buy a stethoscope.Ie a hat will not do anymore.

Regards ,

I finally do understand why you are concerned about the mechanical vibration of your transformer. A good platter mat can isolate the LP from such low level disturbance. Also, sometimes you can make mechanical transformer hum go away by judicious tightening of the bolts that hold the transformer laminations in place. You have to do this very carefully (don't just crank down on them with all your might) and symmetrically (tighten all of the usual four bolts a little at a time and see at each step whether the hum is reduced or finally gone).

Can you hear the hum with the bell of your stethoscope placed against the platter mat, where the LP sits? If not, no worries.

"Mercury" in flu vaccine
Sorry this is way OT, but it is one of my pet peeves.
There never ever was any "mercury" in any vaccine. In some vaccines, like inactivated influenza virus vaccine, there is and was thimerosal. Thimerosal is not free mercury. Thimerosal is an organic (carbon) compound which contains one atom of mercury per molecule in covalent linkage. The thimerosal is there to reduce the risk of bacterial contamination of the vial; it is basically an anti-septic. About 15 years ago, someone added up the amounts of all the thimerosal then contained in all childhood vaccines and discovered that it could exceed the safety limits for an infant. There was a furor in the US, and thimerosal was removed from all childhood vaccines very shortly thereafter. Currently, there is no thimerosal in influenza or any other vaccines given to children. There is still some thimerosal in multi-dose vials of flu vaccine(but not single dose vials) intended for adult use. Thimerosal intoxication is not linked to Alzheimer's or Parkinson's disease, except by hysterics, and anyway was never at issue with vaccines. The amount of thimerosal in vaccines where still in use in rare cases is (and always was) way way below even theoretically toxic amounts for adults and even for infants, except for the potential cumulative dose to infants as of about 1995, as noted. (No thimerosal now in any childhood vaccine at this time, to repeat.) Naturally, the anti-vaccine folks have seized upon this and other red-herring issues, as a reason for people not to get vaccinated. The long term consequences of not being vaccinated are negative for all of us (because of the loss of herd immunity against certain diseases). This is why we lately have outbreaks of polio, mumps, and measles in the developed world. People die from those diseases, sometimes children.

My profound apologies.
That blather about thimerosal was in response to a post on another thread. As the late great Gilda Radnor might have said in the guise of her TV character, Emily LaTella, "Never mind."

Wow, what a great thread. However, no mention so far that Goldmund and Micro-Seiki
used JVC core motors.
Anyone care to elaborate on this?

Wahwah, I recently found out that the Luxman PD-444 (made by Micro-Seiki) used a slotless/coreless motor. So MS apparently used both?

Lewm, I thought some more about it and tried a new test: I lowered the stylus directly on the Achromat platter mat, at zero rpm of course, then I raised the volume to twice my listening level and I couldn't hear the transformer humming in my speakers. So, 'if it ain't broke, don't fix it' seems to hold here. I am leaving well enough alone.
Gary

A little stethoscope is a dangerous thing, because it imparts a little knowledge.

Aren't cliche's just peachy.

I don't dare buy a stethoscope for fear of feeding the neurosis. What if I heard some noise from underneath the platter? I wouldn't be able to sleep until I eradicated it.

Wahwah: "However, no mention so far that Goldmund and Micro-Seiki
used JVC core motors. Anyone care to elaborate on this?"

From the few pictures I saw of the Goldmund and Micro-Seiki motors, they are not coreless motors. The motors are definitely made by JVC but they are not the later coreless version. They are similar to motors in turntables like JVC QL-5 and QL-7, DC core motors.

I have used those JVC turntable models with core motors before and I prefer the later models with coreless motor. That's why I am not surprised someone prefers the Dual coreless motor in the Goldmund after replacing the stock Papst or JVC motor in a repair.

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