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
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?
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.
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.
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.
Vibraplane was something that I looked at initially as well and it seems that ebay is the best source. The price is right but there is not a lot of information about it. Most sellers only shipped within the US and some will only sell it as is with no guarantee that it is actually functioning :(
I am also worried about servicing if the unit has a problem overhere! So Minus K seems like a safer choice for now.

I think that using separate platform on top of Minus K will also allow for easier centering of the mass rather than using a larger custom top. I am a bit worry about using aluminium as top plate as well. In the past, I experimented a bit with aircraft grade aluminium platform under speakers, turntable, amps etc. I find it to give better impact, more focus bass, extended top but at a cost of adding hardness and edge to midrange. Of what I could find locally here for TW, I find black granite (one of those with higher density than regular granite) to be better than local pooltable slate slab and both better than aluminium by a bit. I wonder what would be a good footer for the slab of slate/granite on Minus K since there is a little screws on top on K Minus so I can't lay a platform on top directly.