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TW Raven Owners: Set Up Questions

Through the magic of sweet talk, I turned my Orbe into a Raven and mounted my Graham 2.2/Benz LP.
I am looking for a isolation base for the Raven. I have a 1 3/8" piece of granite coming soon so I can ditch the MDF I use now (a temp. meas.!) Symposium, SRA, HRS, etc., can anyone share their experiences with isolation bases? I saw the thread about loosening the Stillpoints.
Initially I had an issue with using the rough side of belt. The belt shimmied up/down on the pulley at a specific spot on belt. Also, the speed fluctuated and I could never get it dialed in with the PSU. So, I went to the smooth side of the belt and then raising the back side of the motor (unscrewing one of the isolation feet) slightly moving the belt down from "center" on the pulley. This moved me from 33.2 to 33.3 and I have no more belt shimmying and the speed is rock solid.
I'd appreciate any tips/tricks etc.
gerardff

Showing 5 responses by peterayer

peterayer
1,382 posts
 
I used to have an unsuspended SME Model 10. I first tried Mapleshade brass cones on a 4" thick maple block. Not great. I preferred placing the turntable right on the top shelf of my Zoethecus rack. Then I bought a Townshend Seismic Sink for about $200 on Audiogon. Huge improvement. Better dynamics, more clarity, better detail, and deeper, more articulate bass. Then I bought a Vibraplane platform and it did eveything the Seismic Sink did, only more so. Finally, I installed a 136lb steel ballast plate to preload the Vibraplane and this improved the performance of my SME even more.

I'm a big believer in proper isolation now, especially for unsuspended turntables like the Raven. I strongly recommend a Vibraplane.
peterayer
1,382 posts
 
Ebm, it's engineering and Halcro sounds like an architect. I understand about these prestressed concrete slabs. They are thin, and do flex, but they don't break under the design load. Think of a very hard, yet bouncy web. I imagine that they could even ring under certain loads.

Suteetat's apartment floor slab does not at all behave like a thick concrete slab on the ground. Whether or not a wall shelf would be better in his situation, I can not say.
peterayer
1,382 posts
 
Suteetat, I can't answer that. And I'm not sure you will ever get your floor to flex. I'm just saying that Halcro is describing a type of pre-stressed concrete slab and it will not behave like a standard concrete slab located on the ground. You may not have any issues at all.

However, if you can borrow a Vibraplane or other serious isolation platform for you unsuspended turntable, you should hear quite an improvement in information retrieval or resolution.
peterayer
1,382 posts
 
I used my Vibraplane on the unsuspended SME Model 10 and noticed a significant improvement. I now have it under my suspended SME Model 30/12. I would say the improvement is only very slight as the 30/12 already has a superior suspension and I don't think that the Vibraplane offers much additional isolation.

I have also heard the Vibraplane under unsuspended Brinkman turntables and the sound was extremely good, though I can not say what actually contributed to what in those unfamiliar systems. I did hear though that that Brinkman dealer sells a lot of Vibraplanes for his tables.
peterayer
1,382 posts
 
You can get around this centering issue somewhat by trying a Vibraplane. It is not as sensitive to balancing a load to be very effective at isolation.
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