I had to use a spare VPI TNT armboard under the rim drive platter bearing support to achieve correct height. It is acrylic and very well machined. Absolutely quiet. Looks and sounds wonderful!

jloveys August 26, 2008 09:50

Nicely done; detaching the bearing and support for the rim drive platter from TT plinth should have reduced conduction of vibration into stylus. Hopefully it's quieter than VPI's own rim drive cassette, which apparently requires soft feet to add compliance back into the system.

dgarretson August 25, 2008 18:25

System edited: the RIM drive platter is now directly coupled to the Symposium Ultra platform, not on the TNT chassis anymore. I use a Michell TT belt around the main superplatter for contact with RIM platter. Thread between motor and RIM platter. Speed is block steady and the TT is sounding better. Pictures to come soon.

jloveys August 25, 2008 10:01

OK Pedrillo, I buy my ticket to Denver for october RMAF, seems like a cool show.

jloveys June 13, 2008 04:26

It would be great to meet at the RMAF. And to share our stories of upgrades!!!!
Big fan of french cuisine by the way!

pedrillo June 13, 2008 01:52

Oh my ! Is this system sounding good ! For me the main trick is NO PREAMP.
Everytime I use the preamp the sound is dull , when I hook directly the phonopreamp to the amplifier, it is so transparent, makes the whole system disapear, just you and the music. Wonderful. I just did the same thing with my ARC VT 100, the Allaerts Finish is so low output ( < 0.2 mV) that it works even with no volume control. I am waiting for the Tron Phonopreamp with 80 dB gain to use the MC 275 who has vol. control. The Graham Slee has not enough gain, but even so this cartridge is amazing.

jloveys June 08, 2008 01:21

System edited: Winged Logans !
I tryed this since 2 month before editing. I fixed one Magneplanar MGMC1 on each side of Ascent i and stunning results... wider soundstage, less rolled off high frequencies due to ribbon tweeter and very "enveloping" transparent sound.
Overal a nice and cheap tweak. I try now with TWO wings on each Logan, as I have 4 MGMC1 from my ex-surround system. Keep you in with that one!

jloveys June 05, 2008 09:23

System edited: I edited a more complete description of the system, I am sure I omitted things, specialy new tweaks I try for the moment, but I don't edit before beeing sure it is a worthwile objective upgrade.

jloveys June 05, 2008 08:54

Dear Hifibri, switching the rotating direction of the 300 RPM synchroneous Hurst motor is very easy, I had a look at Hurst website and there is a very simple electric shematic drawing , so no risk of error. It takes me 5 minutes to do that with no tools ( only a philips screwdriver for bottom plate ) .

jloveys June 04, 2008 23:10

The purpose of this modification was to try a rim drive with existing VPI parts after upgrading the old platter to new superplatter. Just to experiment, at no expense, to see if this type of upgrade is effective. This turntable (TNT 3) has a round cut, so the HRX twin motor rim drive does not fit. Adding this to the second platter to avoid one step of belts does not make sense to me, because it will not be a cost effective upgrade anymore. But, as you suggest, and for sound experiment I will try this with a borrowed unit from a friend to see if it is worth the expense.This means 3 platters (2 big and 1 small) and still 2 rubber belts, with 2 motors should speed be more stable. I keep you update...
I must also add that i can't compare my rim drive system to the stock VPI because the standalone rim drive is not on the market yet. All I can tell is that it makes a more solid musical presentation than the one platter system. And even more since thread replaced rubber belt.

jloveys June 04, 2008 22:02

Correction; as I was lowering the arm onto my table last night I realized you would have to change the direction of the drive motors of you were using Harry's stock rim drive for this application. My thinking was first to retrofit the existig stock motor to rim drive which already turns in the correct direction without modification, then thought why not use Harry's and save the trouble, not thinking it does not turn in the correct direction for this application, proving once again music improves one's thinking and that I should listen more often...

hifibri June 04, 2008 17:29

Great project! How about using Harry's rim drive (and dual motors) to drive the first platter and dispense with the rubber belt/thread/tape all together. You would not have to re-wire the motor(s) to get the platter to turn in the correct direction. I would think that if a rim drive is better than other methods this would be the way to go and a heck of a lot easier to implement. Anyone try it?

hifibri June 03, 2008 19:37

That's the major problem with thread IME. Even if you find some with zero elasticity it doesn't have enough surface area to avoid slippage on some transients.

dougdeacon June 01, 2008 20:25

It's interesting that despite the heroic effort of a rim drive wheel with even greater inertial mass than a stock VPI rim-drive flywheel, you found that speed stability was perceptably compromised by even a single elastic rubber belt in the sytem. My guess is that you've about reached the limits of the design-- assuming you're using a good speed controller to quiet down the 300 RPM motor.

Since even thread has some elasticity, the only place to go to further reduce compliance would likely be tape as advocated by Doug, or to a direct-coupled, high-speed, high-torque motor-- such as was used in some classic idlers. I tried a less elastic alternative to carpet thread-- Stren braided fishing line-- but was unable to get it to grip well.

dgarretson June 01, 2008 16:15

Jlovey,

Nice system, and good work improving your TT drive.

I agree thread is better than a rubber belt, but neither comes close to the speed stability of mylar tape. I echo Dgarretson's advice and don't worry about slippage against your platter. The circumferential contact area is large enough to prevent that.

A good mylar belt is difficult to make, set up and maintain. There is zero room for error because mylar is inelastic, which is also why it works so well. Each component must be perfectly levelled, perfectly positioned and there can be no elasticity between components connected by the belt. But once you get everything right you will never go back - I guarantee that. :-)

P.S. As your speed stability improves you may need to alter (lower) arm height. I don't know how often you adjust. We do for every LP, and have notes going back four years that reveal consistent arm height changes depending on the belt.

dougdeacon June 01, 2008 15:51

System edited: Moved from rubber belt to thread belt with great results on speed stability.

jloveys May 31, 2008 20:15

System edited: Upgraded the Allaerts MKII to Finish Gold, but the Graham Slee phonopreamp is not having enough gain, so I ordered the Tron Seven to replace it. When it is there I will make a review of it.

jloveys May 31, 2008 20:07

The holographic mylar streamer tape used on Galibier TT seems interesting,but the VPI rim platter is aluminium so it might slip. Maybe glueing a vinyl tape around the platter and motor shaft will resolve this? I will try. In meantime I will try thread drive as suggested by Dgarretson.

jloveys March 07, 2008 08:10

Thank you Dgarretson and Pedrillo ! Having nice feedback from the two master
TNT tweakers is very helpful. It's by watching at the evolution of your setup that
I have done this upgrade. The sonic difference is quite important, in fact it is more on the whole foundations of the spectrum like switching from a small turntable to a massive one, from thin to big and thight. Similar as removing the
rubber ball feet to direct couple the table to the Ultra platform.
Sorry for my bad english, I am french speaking nuts !

jloveys March 07, 2008 07:33

Excellent job!!
Can you describe what differences you heard after the mod. I was considering doing this as well when it was suggested to me by dgarretson.
Keep us informed of your progress.

pedrillo March 07, 2008 04:55

There is useful info on the Galibier site on how to make a tape drive:

http://www.galibierdesign.com/support.html

You would need to make a custom pulley or employ a lathe to cut a smooth channel into the stock VPI pulley. While perhaps not quite as stable as tape, thread drive is easier to implement and IME improves upon a VPI rubber belt.

dgarretson March 07, 2008 01:07

Well... the sprung suspention was replaced with the air ball upgrade, but it didn't impprove anything, so with help of Roy Gregory (HI FI +) I completely got rid of VPI feet and coupled the TT direct to the Symposium Ultra platform with a set of three rollreblocks Jr, as you can see on pics. Very big sound improvement.
The O-ring is in fact a piece of rond section plain rubber wire 7 mm diameter
cutted at platter circumference and glued with pattex on alluminium part of it.
The pressure of the O-ring against the main platter can be adjusted because the subplatter is lying on TT with weights only. I check the ideal pressure with a stethoscope(no slipping or belt noise). the rim platter can be also used as an speed controler if you put a strobe record on it(I use the clearaudio one)
Can you explain to me how to make a tape drive? Thank you.

jloveys March 06, 2008 14:38

Nice mod that should surpass the speed stability & quietness of VPI's own rim-drive, due to the higher mass of your drive platter and the slower rotation and wider contact area of the O-ring at the interface. Using the spare platter for this purpose helps justify costly upgrade to HRX platter.

Did you reduce compliance in the drive system by eliminating the TNT's sprung suspension? For reduced compliance & increased speed stability, it might also be interesting to try multiple belts or thread or tape drive between the motor & the rim drive platter. Where did you source the O-ring?

dgarretson March 06, 2008 13:54

I must ad that the RIM platter is turnning CCW so you have to reverse the phase of the Hurst 300 RPM synchroneus motor by switching red and black wires on the under part of the heavy motor housing. The VPI SDS is obligatory to have exact speed, I tryed to use peripheric ring clamp in place of the O ring but speed is then too high and so is not good. I am building a new stainless steel bearing base similar to the motor housing to decouple the RIM platter from TT and it will be lower so I can use the peripheric ring clamp on main platter.

jloveys March 06, 2008 12:09