A $300-$400 turntable tweak

Hi Henry:

Yes, I've tried various peripheral rim clamps and vacuum clamps (both add-ons and integral). In this case I found that I usually preferred the sound without peripheral or vacuum clamps. Even on my Micro-Seiki SZ-1S, which has a 28kg machined stainless-steel platter and integral vacuum clamp as well as air bearings for the platter and motor/flywheel, I ended up keeping the air bearings engaged and defeating the vacuum clamp (although I did prefer to insert a mat between LP and platter surface).

However, this is probably due to the fact that I own very few warped LPs. If I had more warped discs, I suspect that I would feel a greater fondness for peripheral or vacuum clamps.

In fairness, none of the peripheral or vacuum clamps that I have used offered such fine-grained control over the clamping force as my adjustable magnetic center clamp. I suppose that I could design such a peripheral clamp, but I have far too much on my design plate already!

cheers, jonathan

Dear Jcarr: From your lates post: could I infer then that the subject is not if the peripheral or vacuum clamp or even " normal " clamps are good or not but the " range/level "/push-down force ( quantity. ) of control?

Regards and enjoy the music,
Raul.

One more story - FWIW

A few years ago I bought a center weight to try in place of the threaded clamp on my VPI TNT. Did it make a difference – not sure. It did look nicer spinning around especially when the light caught it. It also did make the dishwarp records worse - since it was strictly a weight concentrated on the middle so the lp edges rose more. That is a fact that I didn’t realize till I brought it home. It bothered me that the manufacturer who must have known this didn’t say anything to me about it.

So I saw that another niche was created and ring peripheral weights had come out. Being a crazy audiophile guy I was ready to buy one of those rings too :( but it would not fit on either of my VPI or SP10 platters because my tonearm design was too close for clearance. So never got that far like some of you. Now from what I am reading maybe it was a good thing.

So I have tried a few more various center weights like all of us – and have gotten to the point where I don’t use any of them anymore except the following basic clamps for dish warp records. They are cheap and allow u to exert the force required to flatten the dishwarp record.

The standard vpi rubber washer/ threaded clamp for threaded spindles.

The michell record clamp is a clone or like the VPI one for threadless spindles and I use it on my sp10.

Both of the above clamps cure for me the slightly warped/dish warped lps. Many more modern records 70’s - 80’s and newer are dish warped because they are so thin as we know.

My records are also not that bad. If I had one or two that one of these basic clamps did not cure enough to play I would replace it or not play it.

Hope this helps at least one person.
YMMV

Cheers

On your direct drive you might want to consider the impact of added weights and peripheral clamps as it may be negatively impacting the servos which have been designed for the original mass of the original platter.
On my Final Audio Parthenon it uses a 1.2kg gunmetal weight which has a proud rim around the bottom. The copper mat has an indent for the record label.
A washer sits under the record and the weight goes on top of the record. What I have found useful is that I have made several washers of varying thickness to optimise the flattening of the record. Obviously a peripheral ring might be better.

Ct0507

With a centre weight you get rid of the lifting record edges by optimising the thickness of the washer under the record. When you get the right thickness of the washer you can get the records flat around the perimeter.