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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
stereo5's avatar
stereo5
6,279 posts
 
I had the same problem with my VPI Scout turntable. I tried everything, then bought a KAB rumble filter. It worked like magic and did not subtract any bass from the music. There is a used one here in the classifieds for 99.00. I paid 169.00 plus shipping for mine, new. You insert the filter through the tape loop and when you play records, put the tape monitor to tape or it can be installed between the pre and power amp.

Bob
jamo1
16 posts
 
If possible, have the wall shelf attached to an outside wall or strucural inside wall as mentioned(behind the speaker plane). Try to set up the shelf so that it is not rigidly coupled to the wall, don't over tighten the screws and perhaps put rubber washers as spacers behind brackets at wall. Then decouple the table from the shelf surface by putting a seperate MDF board or buthcher block on it seperating it with cones,vibrapods,small spikes,rubber/plastic pads etc. Take the lid completely off while playing(antenna for airborn vibrations) also mentioned. Give the cartridge bolts a good tightening and make sure the tonearm bearing is not loose. If this don't help I would say you need a better table.
amandarae
512 posts
 
Me, I will build one (OP amps base) if I need one. There's a lot of circuits floating on the net somewhere. It is much cheaper to DIY.

If you do not want to deal with the hassle, just buy one (KABUSA carries them just like Bob already posted). Or for the best solution, get a new preamp that has one(i.e. Cambridge Audio 640P for a cheap alternative).

Of course, the cheapest way is to move the TT further away from main speakers, hoping that it will solve the problem.
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.
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