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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
winggo
25 posts
 
It may be the turntable. I had an old PL-50 years ago and it had an aluminum platter that rung like a bell. If you could borrow a different turntable and set it up on the same shelf at least you could narrow down the problem.
auxetophone
114 posts
 
If possible, try lowering the stylus on a disc without the platter turning, and then rapping on the wall, platter, plinth, platform etc with volume at realistic loud levels to get some insight into what is happening.

This may help you avoid less-promising approaches, and more quickly evaluate potential cures.

Keep in mind also that although a rumble filter will probably help, ideally you would eliminate the problem at it's source (assuming that's feasible), since your cartridge and phono stage are processing that rumble even when you filter it out.
handymann OP
383 posts
 
I will try to get a pic of my set-up on line. I actually improved my problem by spiking my TT on a piece of MDF and put the MDF on some foam rubber. I can now increase my volume several db without any feedback and the spikes are responsible. What I need is some type of jell material I can place under the MDF board. Can anyone think of a soft jell material I can put under the MDF board? You know I had a friend that hung his TT from the ceiling and it worked great. I may try that too. Thinking as someone suggested part of the problem may be in the actual TT construction. I can peck on the TT at high volumes and hear it. As I mentioned, going to audition a Clearaudio CMB Friday. Guess I will see then. As far as filters go, I already have a rumble filter on my cheapo Balleri VP130. I kid you not, for the $$ that phono stage is well worth the bucks. Thinking about going to the YS Concerto Plus. I don't want to invest bookoo bucks at this time. Actually read a review where the YS won out over the Audio Accoustics PH3. Anyway-I'm making progress on my feedback problem. Will keep you all updated. Thanks for all the ideas.
auxetophone
114 posts
 
Here are various Sorbothane devices. One of them may work for you:

http://www.amazon.com/s/ref=bl_sr_hi?_encoding=UTF8&node=228013&field-brandtextbin=Isolate%20It%21
moonglum
619 posts
 
11-22-10: Auxetophone
If possible, try lowering the stylus on a disc without the platter turning, and then rapping on the wall, platter, plinth, platform etc with volume at realistic loud levels to get some insight into what is happening.

Although I appreciate the reasoning, rapping on the platter (and perhaps even some of the others)sounds a dangerous proposition as the platter can easily be disturbed in the wrong direction leaving the owner with an expensive headache....
I'm not even sure that previously securing the platter gives the required degree of confidence. Very much done "at risk".
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