Vintage DD turntables. Are we living dangerously?

Regards, Hiho: A TT71? Guilty. Picked up for little more than pocket change several years ago just to fiddle around with. A hard maple plinth & EPA-250 tonearm. Swapped around some mats (the OEM mat is terrible) & ended up with a Boston Audio Mat2. The basket shrouding the electronics rings, so strapped a couple of bungee cords around it. Cyro'd bungees are in short supply, used what was available. Bluejeans brand entry-level low capacitance cables & some Isonoe feet at the corners. Pulled the Pio. Exclusive PL-70L 11 & then sat for a semi-serious listen.

The little 71 lacks the ability to capture micro detail but is engaging and involving, I like your reference to flavors and colors :). You mentioned Raul; the gentleman also sampled the TT71 and actually praised it, I believe he used it "nude".

No Timeline available but out of curiosity the 71 was timed for eighteen minutes. From a cold start it immediately advanced a nominal four degrees and then remained spot on for the remainder. It's been a while since researching but IIRC the 71 lacks the reverse eddy current braking both the 81 and 101 implement in regulating overshoot incurred when correcting for speed. Other than the coreless motor, the only other difference for the 81/101 is the readout for the 101 is digital, the 81 is equipped with a strobe.

Just an enthusiast, I find critical listening a distraction. I've not read a negative comment concerning either the TT81 or 101, JVC seems to have gotten the series right. Of this I am certain, in spite of, or perhaps because of, the resonant character of the modest 71 it is somehow a captivating performer. Some day I'll return to the PL-70L 11 with it's "stable hanging rotor" drive and exquisitely engineered PA-70 tonearm and then experience a revelation as to what I've been missing.

In reference to Halcro's OP, among others I've a Tech. SP-15 which I expect to someday start spinning like a gyroscope and a Denon DP-60L (a carnival of resonances) with it's fragile magnetic tape attached to the platter.

Pardon the lack of references, corrections to any of the above are welcome.

Peace,

04-04-14: Banquo363:
"The english flyer for the jvc ql8 has a small black and white pic of the tt81 motor. Take a look and see if you can tell whether it's a coreless motor or not."

Good find!

TT-81 motor - & - TT-71 motor

Yep, just as I suspected. The TT-81 motor is indeed a core motor, same structure as the TT-71 motor. Notice the coils wrapping around an iron core? You just save Halcro the hassle of taking apart his TT-81. :)

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Timeltel, I like your tinkerer's spirit. :)

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Halcro, That's great news about your TT101, and it is useful to know yours was malfunctioning due to bad power switch. Can you describe again the symptom that it exhibited before repair? Bill Thalmann often wondered whether the switch on mine was bad as well, and that could account also for the fact that mine would work well off and on, once it had been re-capped and re-soldered. Also, it explains why leaving the Power ON is a form of solution to the problem short of replacing the switch. Where did he get a replacement switch; perhaps you can ask him what he used, just in case any of the rest of us has issues.

By Sunday, I will have completed my mods to the stock QL10 plinth. They are anti-Copernican. I will post photos, and best of all I will finally get to listen to a TT101.

Dear Timeltel, You wrote, "the 71 lacks the reverse eddy current braking both the 81 and 101 implement in regulating overshoot incurred when correcting for speed". According to everything I have read and observed, that is not correct at least for the TT101. The TT101 is unique among 71, 81, 101, in that it has a reverse servo mechanism to correct for overshoot. Nowhere have I ever seen this described as eddy current based. I have no insight on whether or how the TT81 can slow down its platter. I do know that one sign that my TT101 is running as intended is that when I press the "stop" button, the platter comes to a dead halt. When I was having problems, the platter would stop but then rotate backwards for about half a turn before lazily stopping. This indicated to me that the reverse servo was not working properly.

Someone else suggested that Exclusive P3 and P3a did NOT have a coreless motor. My information says they both DID. (They were not really two different turntables; the way I hear it, there was a change in the way rumble was measured and Pioneer re-named the table from P3 to P3a so they could claim the new re-calculated lower number for rumble was associated with something they actually did to the table to improve it.)

Also, Denon tt's were said to have an "induction motor". That would be hard to do with a servo-controlled DD turntable; so far as I know the Denon DP80 has a 3-phase synchronous motor.

Lewm: "Someone else suggested that Exclusive P3 and P3a did NOT have a coreless motor. My information says they both DID."

It does not look like the traditional pancake style coreless motor. Judging by this picture in this webpage, it might be a linear motor, which has magnets on both side of the coils like maglev train, with a cylindrically shaped stator with coreless coils, it might be a coreless motors after all. In that picture, the top motor is just an illustration what a traditional motor looks like and the bottom motor is the EM-03 motor P3 uses. It's a novel way to making the stator much like the ThinGap motor used in the VPI Direct table.

Lewm: "Denon tt's were said to have an "induction motor". That would be hard to do with a servo-controlled DD turntable; so far as I know the Denon DP80 has a 3-phase synchronous motor."

DP-80 does not use induction motor but earlier models, pre-1975, some models used magnet-less induction motors. Chronology is the key here.

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