AR turntable With Ortofon OM 20 super? & phono amp

thanks Opal..

I have an older OM-20 (not Super) that I picked up in a Goodwill and have used occasionally in a pinch. In my opinion, it's a very nice sounding cartridge for the money, which I could be perfectly content with. And if you decide later to upgrade, the OM30 stylus fits right into the same cartridge.
The OM20 is much higher output than the V15's were so you'll have more gain with your present phono stage.

The cones should be threaded into the TT with the point facing down.

An effective CLD that can rest on top of an existing support structure can be built out of the following materials, working from top to bottom.

A layer of felt

a sheet of 24 gauge stainless steel

1" of industrial grade foam insulation

A layer of cork ( as used in a cork-board )

The felt absorbs any motor noise and damps any ringing that may be reflected from the bottom of the TT or generated from the sheet of stainless itself.

The stainless provides a solid platform for the cones to rest upon. Stainless isn't ferro-magnetic, so it won't play games with re-radiating the EM field generated by the TT motor like some cheaper metals would. You can use aluminum here, but it would have to be of a significantly heavier gauge i.e. give or take 20 gauge or so. This adds mass, which isn't what we want.

The foam acts as a "layer of loss" i.e. an energy sink for the vibrations that the cones couple and "drain" into the stainless. That same "layer of loss" also helps to isolate floor-borne vibrations from coming up into the TT.

The cork acts as another layer of loss, but in a different manner. Due to the difference in mass, density and construction, it is more effective in dissipating energy at specific frequencies and breaking up nodes.

There are multiple other ways to do this, but this approach is both cost effective and the materials are typically easy to obtain.

If you wanted to use this as a shelf itself rather than as a base on top of an existing shelf, you can add another layer of felt coated SS at the very bottom. This would provide the necessary rigidity to keep the shelf from buckling under the weight. This should be able to support most any component that you throw at it short of a heavy amplifier or very complex tube based preamp, etc... Sean
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Also, Sean are you saying to actually mount the Cones With points UP(like in a 1/4" piece of Masonite) then set the Table on them spiked to the wood edge? Or mount the cones threaded into the Table standard wise and set that down on a Masonite type board with like a cut to fit piece of Blackhole 5 or something like that? Pretty confused, but either way this is very easy and worth it for very little money if very effective, please elaborate more specific and on the materials used and exact construction you speak of. Thanks

I am considering now on this site an ad for a New Rega 300 arm with an ortofon om 20 mounted for 300.00... seems like a very good deal and possibly the best bet..

Now to the Isolation platform, please point to exactly the materials and type cones you refer too? and how to construct, I can do this very easily if I know what to purchase, it sounds like a good idea, and I rather go ahead and tweak out the table cheaply at this point and go the route of a better phono pre and call it a day for like I said a few hundred, it makes a little more sense to me at this point..

With this table, you need to replace the stock footers with some decent cones and then mount the cones on top of a constrained layer device ( CLD ).

If building the CLD / shelf from scratch, don't make it so heavy that you defeat the purpose i.e. the added mass will help to couple it to whatever it is that you have the TT and shelf resting on. The idea is to use the constrained layer shelf as both an energy sink for the air-borne vibrations that the TT pick up and transfer through the cones AND at the same time, use it to isolate heavy footfalls / floor-borne energy that might be transferred up into the rack or support device itself.

The key here is to retain a high level of rigidity to support the TT in a level fashion, but at the same time, make the constrained layer device less dense so as to be self-damping i.e. an energy sink. By using a thin but rigid layer on top and a softer, less dense layer ( or two ) of material underneath that, one can pretty easily achieve this goal. The more layers that you use, and the more dis-similar the materials, the greater the efficiency of the CLD.

Other than that, this table / arm works best with a low mass, higher complaince cartridge. As far as sound goes, the Shure will sound "beefier" but less articulate and far less "nimble" as compared to the Ortofon. Personally, i would consider the Ortofon to be a superior cartridge when properly loaded, but that is obviously a matter of personal preference and arm / table compatability.

In terms of phono stages, i have no idea what you are currently running as far as preamps go. You might be better off investing in a good but used "one box" preamp with a well designed phono stage instead of using an outboard yet mediocre phono stage. For what a decent phono stage costs, you can buy an even better preamp. Sean
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