Vintage DD turntables. Are we living dangerously?

From my understanding of the Goldmund Studio situation is that...

1) If you have nonworking motor, you need to replace it with...
____A) Stock Papst motor, if you can find one.
____B) Stock JVC motor, if you can find one.
____C) EDS-1000 motor salvaged from Dual CS-701 turntable.
____D) EDS-1000-2 motor salvaged from Dual CD-721 turntable.

2) Read quote from below:

"Dual 701/721, EDS 1000/EDS 1000-II- These motors are 5.5" in diameter, while the original Goldmund Papst is 4 3/8", so machining is required....... Further, both motors are fed via their own electronics, and MUST be used with it. It is not bulky, will fit inside. All in all, I would only recommend these if all other options are exhausted"

Personally I would prefer the 701 motor for this purpose because it was designed for a heavier platter (2.9kg) as the 721 uses a lighter platter (1.5 kg) and has less torque. Go for the 701, I say. All the electronics are underneath the motor and the power supply is in its own enclosure so that can be outboard from the table. There is an umbilical cord for the 33/45 speed switch and two pots for speed adjustment. You can eliminate the strobe light if you want.

Again, the person who did the conversion emphasize that he would "only recommend these if all other options are exhausted."

You have been warned. :)

P.S. Or you can simply buy a beater 701 and take out the motor and electronics and make a simple plinth for it and have a listen like this guy.

_______

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.

_______

08-28-14: Lewm:
"What bothers me about it is the question of whether the pivot is really held "Rigid" by the floating bearing arrangement. I don't see how it could be. "

In the August 2014 issue of Stereophile, Michael Fremer reviewed the tonearm and wrote something about the bearing:

"The arm lacks a conventional bearing. Instead, the pivot floats on a dark, magnetic, light-viscosity, ferrofluid-like oil that you inject into a large opening at the front of the pivot housing. Before you do, the arm is too stiff to pivot; afterward, it smoothly glides on what appears to be a bubble of oil without visible means of support. According to inventor Akimoto, inside the pivot, a small ball floats on a “slimy rubber swimming ring that regulates the arc motion of the wand.” There must be a cup-like structure inside that holds the oil, and a vertical rod—the pivot point—that is somehow steadied by but floats within the oil. I couldn’t pull the arm to and fro, and yet it floated freely. Very ingenious, however it works!"

It sounds like the arm might be a modern remake of the Gray oil damped unipivot design using "magnetic fluid." But the distributor claims the following:

(1) Absolutely no mechanical contact at arm pivot bearing mechanism, resulting in highest sensitivity and maximum amount of howling margin (Which promises to reproduce rich but much tight base sound with no distortion, no muddiness, the most clear sound and wider dynamic range).
(2) There are similar type of bearing pivot, dipped in oil bath (Oil damp Type), available in the market, but still they require some string or another apparatus to fix fulcrum for arm rotary motion but RF, thanks to automatic positioning mechanism, requires absolutely nothing to interfere with the force, for cartridge stylus to follow the inward path of record groove.
(3) There might arise some lateral mechanical instability of arm with this type of bearing, but RF, equipped with the most appropriate balancing mechanism, assures the stability of the focus. This is the reason to be put the name of ""Rigid Float"".

So in the end, I don't know.

.

rwwear: "I'm happy to say my recently purchased JVC QL-F6 works and sounds great. It's not the most beautiful turntable I've seen but could look nice in a custom cabinet."

I am glad that you like the result. It's a gem. As long as you like the tonearm, it's as good as any other tonearm-included JVC turntable or integrated turntable out there that uses coreless motor. I have the same one and the QL-A75 is the only other one I might want to acquire in the future. Yes, she's not the prettiest but she can cook! 

halcro: "If hiho likes it.....it's safe to assume it's very good"

You're way too kind. I've learned more from you, your audio dedication, and your open-mindedness than most people here. My humble opinion is just . . . an opinion. As the saying goes, "trust your own ears." 

rwwear:  "The A75 is beautiful."

Indeed! I meant to say the QL-F6 is "not the prettiest but she can cook" up some good sound! 

Halcro, I am using a Signet TK5Ea. Stylus is on its last leg and gotta find a suitable substitute. Any option if I can't find or afford an original, perhaps certain Audio Technical model replacements?

Rwwear: The only F6 I had was switching between speeds with two big buttons. One speed button can get stuck and I have to press other other speed button forcefully to "pop" it back to the desired speed. Another F6 I owned had the strobe light bulb went off but the indicator needle still works. Other than that, it works smoothly. I'm spoiled by the automatic features, I have to admit. I'm getting lazy these days...

To contact acman3 and click on "send message."
https://www.audiogon.com/users/acman3/feedbacks

To contact lewm and click on "send message." 
https://www.audiogon.com/users/lewm/feedbacks

You can always use the above link as template and just change the username and then click "send message" to that user.  

Most Yamaha DD tables use JVC coreless motors. I took a looksie at the motors of Yammy tables I owned before (PX-2, PX-3, YP-D4) and they all use JVC coreless motors. And judging by the pictures I saw of the GT-2000, the motor appears to be JVC coreless. The GT-2000 uses the motor similar to the JVC QL-A75, with a different arm of course. The GT-2000X uses a more stout fatter bearing than the GT-2000.

Some pictures of GT-2000 guts:
http://blogs.yahoo.co.jp/hakoniwa712/44630587.html

http://blogs.c.yimg.jp/res/blog-ed-36/hakoniwa712/folder/1502328/40/41843040/img_0?1220603098

GT-2000X vs GT-2000 bearing
http://knisi2001.web.fc2.com/gt-2000x-shaft.jpg

Underbelly
http://www.hi-fi.ru/bitrix/components/bitrix/forum.interface/show_file.php?fid=1076934.jpg

More guts picture
http://pbs.twimg.com/media/B8PhUZUCMAAWehU.jpg

Some clever armboard idea to use a different arm.
http://yahoo.aleado.com/lot?auctionID=k203770319

http://auctions.c.yimg.jp/images.auctions.yahoo.co.jp/image/ra122/users/4/6/6/8/lexcoupe430-img600x4...

http://auctions.c.yimg.jp/images.auctions.yahoo.co.jp/image/ra118/users/4/6/6/8/lexcoupe430-img600x4...

with FR tonearm
http://www.ne.jp/asahi/gonzaemon/audio/img/FR64-2.jpg

with SAEC arm
http://auctions.c.yimg.jp/images.auctions.yahoo.co.jp/image/ra099/users/4/6/6/8/lexcoupe430-img600x4...

I never owned a GT-2000 so I don’t know the sonic difference compare to a JVC. But from the other Yamaha tables with JVC motors, they do have that fluidity in the sound. I can see one advantage of the GT-2000 is the extra wide platter. Perhaps the QL-A70 is JVC’s answer to that with also an extra wide platter.

Quite honestly I see enough of the guts of these tables, they are all just variations of the same theme. The attention to details makes the difference, I think. Using a quality motor, you’re winning half of the battle, which I can’t always say that about some sacred cow belt-driver with a toy motor.

Happy DD listening!

TT101 is just the motor drive with no plinth and no arm whereas the GT2000 is a complete integrated turntable. The prices should be different.

The TT61, TT71, and TT81 do not use coreless motors and from my experience with TT71, while it's good sounding, its sound does not have the flowing smoothness of tables with coreless motor like QL-Y66F, QL-Y7, QL-Y5, QL-Y55F, etc... 

ddriveman: 09-12-2016 2:21am  "...one remaining disadvantage of DDs over belt drives i.e. motor vibrations going up the spindle."

It is NOT motor vibration. It is bearing noise, which can happen in any drive system, whether it is direct-drive, belt-drive, idler-drive, or any other drive. The motor of a direct-drive turntable spins at 33rpm, which is half hertz, not reproduce-able in any audio system or loudspeakers. However, many belt-drive turntable motors spins up to 1800rpm, 30Hz, which is definitely audible, hence the need for isolation and decoupling. In DD tables, motor noise is the least concern and in fact it is the most important ADVANTAGE over belt-drive because it has a single slow moving part.