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I Have Airborne Feedback And Never Realized It...Till Now

  While my ZYX Airy is out for a rebuild, I hooked up my CAL cd player/transport and started playing CD`s that I had recorded from vinyl using a Tascam 900.
When I do the recording, nothing is on but the TT setup and the recorder. Room is dead silent. No speakers

I`ve  been listening to a disc or two over the last few nights.

Last night, I was listening to a CD I made of Lindsey Stirling`s 'Shatter Me' LP
I was hearing so many odd/different sounds that I never picked up on before using the TT.

For example, I heard growling sounds (seriously) back ground noises and other THINGS that all were hidden when I was playing the TT.
This LP is Bass Heavy! Lots of energy in the air. With 3 15" subs I know that.

My TT is pretty much isolated IMO
I use a Rega wall mount bracket that is bolted to my equipment rack not the wall.
I have the TT sitting on a SRM isolation platform that sits on the Rega bracket
Concrete slab floor.

No doubt the cartridge is picking up on all energy that and resubmitting it.

This won`t be an easy fix I`m afraid..  :(



scm
chakster's avatar
chakster
6,144 posts
 
Audio-Technica designed pneumatic insulators (AT-616) long time ago and this is still the best solution for turntables under 60kg weight. 
audioguy85's avatar
audioguy85
2,017 posts
 
Here is a far less expensive, not to mention easier way. Take some rubber grommets and use however many between the wall and the turntable shelf/mount. Upon tightening the screws/bolts (what have you) to the wall, the grommets will compress and provide the needed absorption, and or vibration dampening. Rubber washers would work as well....
millercarbon's avatar
millercarbon
12,531 posts
 
You did this?
scm OP
299 posts
 
audioguy85
  "...Take some rubber grommets and use however many between the wall and the turntable shelf..."

I actually used dense rubber matting about 1/8" thick between the two bolts I used to attach the Rega rack onto the center "spine" of the equipment rack.
I wish Agon allowed pics...
lewm
12,572 posts
 
I gotta say I agree with others who think that bolting the shelf to the rack ends up with transmission of energy from the rack.  But the OP is the only one who knows what that looks like.  Maybe there is something about the arrangement that mitigates what we see as a problem. However, the points about fastening a "wall shelf" to a weight bearing wall are correct, based on the received wisdom.  I do agree that concrete transmits energy, but I can't agree it "rings like a bell".  That metaphor calls forth the sound of a bell, metal on metal.  Concrete does not "ring" like that in my experience.  Also, in my house where I have two completely separate systems, one of which is in our finished basement sitting on an indoor/outdoor carpet over a solid cement foundation flooring and the other of which is in our living room on a suspended floor supported by studs (or whatever you call those wood support beams placed about 12 inches apart) and a steel beam as well, the basement system is far less susceptible to floor-borne feedback.  The two turntables in that system produce a very solid image. So, I don't think concrete flooring is to be sneezed at.  It's a good start.
The OP says he is using 3 woofers in this system and is planning on adding more.  Is this the Audiokinesis woofer system or just an attempt to wring out the lowest possible frequencies?  If the latter, that doesn't help with eliminating various forms of feedback.
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