How to eliminate TT feedback/vibration


1st Thing I will tell you - I have an OLD TT. It's a Pioneer PL-71. ( I'm looking at a Clearaudio CMB ) My TT is placed out in front and to the left of my left speaker(per Jim Smith's book.) I made a platform of MDF attached to the wall where my TT sits. At no point does the platform contact the floor. When I play certain albums-several in fact, at mid to high db levels, I get either an acoustical feedback or vibration feedback from low hz. I have tried to isolate my TT using something like sorbuthane balls and foam. I have not tried any of the commercial cone devices advertised. (Do they really work and if so-what's the best product?-no salesmen please). I don't know if my problem lies with my TT, or my platform it's sitting on. I have a friend who actually hung his TT from the ceiling years ago, and I may have to do the same. Thought I would inquire if anyone knew the answer before I started experimenting. Will a higher end TT like the Clearaudio cure my problem? Is it the platform I made-or do I simply need some isolation cones?
handymann
I don't think you need to waste money on more "vibration control" crap, since you've already gone to the trouble of making a wall shelf. It won't do anything to reduce "airborne" vibration picked up by the table/arm/cartridge. I agree with Amandarae. You either need a rumble filter or need to move the TT further away from the speakers.
Better yet, try a set of 'moon gel' pads. Very inexpensive at $6. You can find them at most musicians stores. They are used by drummers to stop vibration. The pad's color is blue, each pad about one inch square. I've used these under tables and speakers.
A sub sonic filter my be needed. As for vibration control "crap", cones could be of great help. I have seen them help in the same situation. I'm not recommending spending a fortune on exotic stuff. You might want to try a set of Dayton dss4 speaker spikes from Parts-Express as feet for your TT. They are really just big brass cones. They are two piece for leveling, but I would screw them tightly together. Use 3 or 4 of them with a tiny bit of adhesive to keep them in place. Worth a try for $15.
Another thing you might consider is removing your dust cover and just placing it over the TT when not in use. The cover seems to pick up a lot of vibration.
Two things you could also try. You could mount the shelf to an exterior wall it should be less resonate and if you are feeling handy you could build a TNT sandblaster both have worked quite well for me. http://www.tnt-audio.com/clinica/diyracks.html
What device do you recommend for a rumble filter? Of course, some phono stages have it built in, but if the one you own doesn't, what do you recommend?