Turnable Rack Vibration

Kenny: That's too bad. That would move me very quickly away from the wall mount as well! I have an older Target wall mount, the one which Nsgarch described with triangular bracing. It is solid as a rock. Too bad that Target has cheapened the product.

Previously, I had used an older Target shelf with a SOTA table but I needed the Pro shelf to accomodate my new table. The old Target shelf never flexed but it was designed differently.

Kenny, that's exactly what I was referring to 6 posts ago ;--) The original version IS BETTER

As for leveling the shelf surface itself, before installing the wall shelf against the wall, put a 3 foot or longer carpenter's level against the wall (vertically) and check to make sure the wall isn't leaning in or out!! It's a lot easier to shim the whole shelf (frame) at the wall than it is to try and level the (horizontal) shelf surface later on.

Dan, for what it's worth (and I've been using Target wall shelves since 1990 ;--) one of the best (and easiest) mods one can make to the MDF shelf that comes with the unit is to make a "constrained layer" damped shelf out of it. Start with a second sheet of denser material the same size as the MDF shelf. I use 1/4" glass, but you can use Corian, acrylic, granite, aluminum -- whatever, as long as it's a harder than the MDF. Then get a sheet of 1/8" - 3/16" thick (maximum) dense foam or sheet sorbothane. Spray the bottom surface of the MDF and one surface of the second material with 3M 88 Spray Adhesive and press the sandwich together, place it on a flat surface and set a couple of cinder blocks, side-by-side on top for 8 hours (you want the adhesive to dry out under pressure!) You now have one of the best constrained layer damping systems in the world! If you can use spikes under your TT, that will increase performance even further.

How it works, is that the vibes drained off the bottom of the TT (by the spikes or feet) travel more or less straight through the MDF (and are just partly absorbed by it) but the MDF itself can't vibrate because it's sitting on something hard and unyielding. When the vibrations exit the MDF and hit the constrained (i.e. mostly squished) layer, they are forced to travel horizontally through the foam or sorbathane until they dissapate. You can pay more but you can't get a better shelf. All by itself, the MDF shelf will bounce (too little for us to see or feel) but it won't absorb! It will transmit the vibes to the metal structure and possibly refelect some back to the TT. That is NOT what you want ;--)
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"Dan, for what it's worth (and I've been using Target wall shelves since 1990 ;--) one of the best (and easiest) mods one can make to the MDF shelf that comes with the unit is to make a "constrained layer" damped shelf out of it. Start with a second sheet of denser material the same size as the MDF shelf. I use 1/4" glass, but you can use Corian, acrylic, granite, aluminum -- whatever, as long as it's a harder than the MDF. Then get a sheet of 1/8" - 3/16" thick (maximum) dense foam or sheet sorbothane. Spray the bottom surface of the MDF and one surface of the second material with 3M 88 Spray Adhesive and press the sandwich together, place it on a flat surface and set a couple of cinder blocks, side-by-side on top for 8 hours (you want the adhesive to dry out under pressure!) You now have one of the best constrained layer damping systems in the world! If you can use spikes under your TT, that will increase performance even further."

Nsgarch: Thanks very much for posting this. As I mentioned earlier, I have an older style Target wall mount that I acquired recently. The MDF shelf was warped and I've never been fond of MDF on its own anyway so ended up buying an appropriate sized piece of 3/4" baltic birch at first before experimenting with extruded acrylic as a shelf (using a Michell Gyrodec).

The acrylic had much better sound quality than the baltic birch but the plastics fabricator sold me a 3/8" inch thick piece when I probably should have gone for 5/8". In any event, the 3/8" flexed a bit under the weight of the Gryo which I was not super comfortable with.

I've always really wanted a Neuance shelf, but alas, Ken Lyon is no longer producing them, so after reading your post above I went out to an upholstery shop to seek out some high density foam. Ended up with 1/8" high density neoprene foam (it can actually be rolled up very tightly and will stay that way, almost like a piece of fabric) and then bought a piece of 3/8" baltic birch. I bought adhesive but actually never used it. The configuration is table, 3/8" acrylic, neoprene foam, 3/8" baltic birch onto the spikes of the target wall mount (metal blanks under the baltic birch at spike points).

My "sag" with the acrylic on its own has been eliminated; I was a bit surprised at the improvement in sound quality. The "constrained layer" shelf is definitely doing its job. Improved high and low frequency performance and a much more transparent and natural sounding midrange. The key words are natural sounding. The baltic birch on its own, as well as higher mass phenolic shevling were a bad match with my Gryo, "enhancing" detail but at the same time considerably hardening up the sound. Glass, marble and granite on their own all have similar, even nastier qualities.

In short, $10 for the neoprene high density foam and another $10 for the baltic birch combined with the acrylic I already had have worked together to make a very good shelf.

Thanks for the info.

HDM, it's very nice of you to confirm my advice ;--) I'd further suggest that you get a thicker piece of acrylic (definitely 5/8 or even 3/4), and do bond the sandwich together under pressure. If you do that, then try flipping the sandwich over (birch on top thicker acrylic on the bottom) and see which you like best. Not saying that it will be better (having the birch on the bottom right now may offer just a little more flex resistance when using it with just the 3/8 thick acrylic) ) but I always say (especially with audio), "Leave no turn un-stoned!" ;--)