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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
pcosta
241 posts
 
Yes I used it only with my TW and I have only had one motor. It is easier to address the centering issues with the short belt for that table.
halcro's avatar
halcro
2,664 posts
 
The 'centring' issue is not a problem if you use a top-plate supported on 4 equally placed 'spacers' over the Minus K stand.
I have checked this directly with Minus K and it's something they recommend.
Just take into account the weight of the top-plate?
pcosta
241 posts
 
Halco

What do you mean by:

The 'centring' issue is not a problem if you use a top-plate supported on 4 equally placed 'spacers' over the Minus K stand.

I would assume the Minus K would not be working as good as it should, not to mention, putting the turntable out of level. In my experience with the Minus K having that top plate lean out of level would be compromising its abilities,
The amount of movemment can be adjusted on the Minus K but you are also adjusting the amount of isolation from its lowest speck on up.
halcro's avatar
halcro
2,664 posts
 
Most turntables (and also audio equipment) are usually supported on either three or four legs so the weight is not evenly distributed over the top of the Minus K stand. It is distributed over three or four POINT loads.
Minus K simply advises that the overall load is placed generally around the centre of their top-plate. Even with my nude Victor DD turntable which weighs 10Kg surrounded by 3 armpods each weighing 12 Kg.......Minus K are happy that the arrangement is CENTRED on the top-plate. In other words.....the load does NOT have to be uniformly distributed.
However I would be happier to add my own top-plate ex butchers block or slate and support it on four neoprene or slate packers on top of the Minus K top-plate.
This would distribute all the loads evenly onto the four 'packers' which would be CENTRED over the Minus K top-plate.
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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