A word about jitters…

I mentioned in a previous article how I was getting feedback through the turntable/subwoofer at anything over moderate volume levels. This feedback  would send the subwoofer into conniptions, even though the table sits on a Target Pro Large wall mount turntable shelf bolted into the side of a brick chimney. That side location is a shallow corner, and most likely contributes to, or is the cause of the problem.

In my search for a remedy, I discovered that there is now a whole industry dedicated to providing products that isolate Ginko Cloudcomponents from their environment. They do this by either attempting to lock the components solidly to their supports/the earth or suspend them as completely as possible. I know everything is relative, but most of these products are a bit over the top for the quality of equipment I have, as well as being a bit on the expensive side to say the least.

Somewhere in the middle of these two philosophies, there is another group that tries to find a more practical solution to building cement piers down to middle earth or air suspension systems complete with noisy pumps. The consensus of this group seems to be that combining unlike materials of different densities/ properties produces a similar acoustic effect to either the isolationist or the structural products. For economic and, more importantly, WAF (Wife Acceptance Factor) reasons, it was this methodology that I decided to pursue in order to eliminate the feedback and tweak my system a little.Ginko Cloud

In what I do for a living (sadly this column doesn’t pay the bills), I buy miles of industrial conveyor belting. Belting is very similar to tires in construction. It is composed of layers of different types of rubber and is interlaced throughout with different types of cord or wire. Belting comes in a wide variety of thicknesses, widths and wear ratings. To me, it seemed like a perfectly reasonable product to use under the turntable and equipment! 

One of my belting suppliers is Thaman Rubber located near Cincinatti, OH (This email address is being protected from spambots. You need JavaScript enabled to view it.">This email address is being protected from spambots. You need JavaScript enabled to view it.). Bill Thaman is a distributor that actually stocks a host of rubber materials and has always been willing to supply samples when requested. I spoke at length to Bill, explained the problem and asked him to send a variety of different sample materials to experiment with. He sent quite a smorgasbord.

Of course your results may vary, but these were my findings:

MDF (Medium Density Fiber board) and the thinnest (1/8”) / softest plain rubber sample he sent had no discernible impact on the turntable feedback over the MDF on its own. Adding 3” diameter thin plastic discs between the turntable feet and the rubber allowed me to move the volume control one or two increments louder before feedback started again. 5/8” belting of a moderate stiffness on top of the MDF moved the volume up 5 increments and 6 with the discs in place …. But it was still not loud enough.

Sound system with vibration control

Next, I tried using a 1/8” stainless steel plate (I buy that too) with both the thinner and thick belting. The thick belting produced improved results with the volume moving up at least 7 increments from the original setting. I was indeed getting closer. I tried it, but the plain stainless steel was not an improvement over the plain MDF. Adding the plastic discs looked nice but there was no improvement to the feedback. Bill had sent along samples of various other solid rubber compositions. I then glued the belting to the stainless steel with GOOP glue; the result was moving up to 8 increments. I was almost there, but not quite. I needed at least a total of 10 increments to get where I wanted max volume to be.

Bill had sent along various thicknesses of single material pieces. I tried all of these between the feet of the table and the belting surface and none of the single compound pieces had a positive effect. The softest compound he had sent, which was white in color, was good for one solid positive increment, but was just not WA.

Out of desperation I pulled out some vintage gel feet I had and put those between the belting and the turntable feet….   Houston I’m at 9 increments with a goal of 10! Trying the gel feet with the MDF previously had a minimal impact. I added the plastic discs to the top of the gel feet and I was at 10 without feedback! On a whim, I glued a layer of that thinnest plain rubber sheet I had tried with the MDF to the bottom of the stainless steel plate and the result was no more feedback at any volume I have tried. Problem solved!

It was all quite an exercise. I can’t thank Thaman enough for supplying all the many samples.

Lastly, during the process of solving the feedback problem with the Clear Audio Performance turntable/Maestro cartridge/HSU subwoofer, I dug out and hooked up my old NAD 5000 CD player. I tried using it through the RCA outputs and also the optical. The optical sounded better, but it was still not nearly as good as the turntable and didn’t flip my switch.

On a whim I took some of the samples I received from Thaman and put them under the CD player, around the CD player and even on top of the CD player to see if there was any sonic difference. Very surprisingly, by using belting strips under the unit instead of the equipment feet, there was a marginal improvement in sound. Then I played around a bit more with different materials including a brick. A couple of heavy pieces of a thick dense single composition material Thaman had sent were my last experiment, since they had no discernible influence with the turntable. But with the CD player, the transformation was amazing. I thought I was hearing things. I had my son blind test what I was hearing and he immediately confirmed my findings. The old CD player sounds better than ever now, better even than the LG Blue Ray Player. To my ears though, it is still nowhere near as good as the turntable and of course, your results may vary.

I exchanged a whole series of emails with Bill during the process and he became intrigued with the concept of using belting in an audio environment, and he kept sending me samples of different materials to try. Great guy. Compared to most of the alternatives and specialized shelving etc that is available, belting material seems to be a steal and can be very effective. Thaman is willing to sell pieces of belting or the other materials to the public. Just email him at This email address is being protected from spambots. You need JavaScript enabled to view it.">This email address is being protected from spambots. You need JavaScript enabled to view it. and no, I do not have a personal nor any financial interest in Thaman.

 

Jim Pitsburgh is a self made audio & home theater expert and well known in the audiophile community.

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