Ever since I installed a Formula IV on Fakedeck, I've been plagued by feedback. He sits on a shelf above on of my speakers, de-coupled (or coupled, it would seem) by a set of spikes, as shown here http://www.thepippin.plus.com/Fakedeck/DSCF0842.JPG and here http://www.thepippin.plus.com/Fakedeck/DSCF0843.JPG
I have tried putting sorbothane pads (can be seen sitting on the A60) under the feet, but that made no difference. Any suggestions?
Fakedeck Feedback...help!
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shane
- Social outcast
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#4
Finally got round to trying to sort this out today, and I'm rather surprised at what I've found. First, I went back to isolating the turntable from the shelf with the Sorbothane pads under the spiked feet. Tapping the turntable with the stylus resting on a stationary record still resulted in a loud "bong", but what I hadn't cottoned on to before was that tapping the shelf now resulted in near silence, so the shelf is not the culprit. I then sat down and scratched my head, and decided that the bottom layer of slate must be ringing. It is supported on three spikes, one in each rear corner and one in the middle of the front edge (second pic in the first post above), so if slate can ring, then it's pretty much ideally supported to amplify the effect!
To test my theory, I supported the whole deck on a three-inch diameter block of aluminium placed under the centre of the bottom layer of slate. Result? Despite now being solidly coupled to the shelf, no feedback and no bong.
Now, I was under the impression that slate was non-resonant. Not so, it seems, and the resonance I found was fairly high Q. The good news is that that makes it pretty easy to control. By choosing suitable placing for the spikes, probably nearer the centre, it should be possible to break up the resonant nodes and kill the bong once and for all.
To test my theory, I supported the whole deck on a three-inch diameter block of aluminium placed under the centre of the bottom layer of slate. Result? Despite now being solidly coupled to the shelf, no feedback and no bong.
Now, I was under the impression that slate was non-resonant. Not so, it seems, and the resonance I found was fairly high Q. The good news is that that makes it pretty easy to control. By choosing suitable placing for the spikes, probably nearer the centre, it should be possible to break up the resonant nodes and kill the bong once and for all.
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Dave the bass
- Amstrad Tower of Power
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#5
shane wrote:... and kill the bong once and for all.
No! Don't kill it... Just have a rest and a glass of water then come back to it. Chill.Oh, 'ang on
You didn't mean that sort of bong did you ? 
DTB
PS. Congrats on sorting out your feedumbackage.
"The fat bourgeois and his doppelganger"
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Dave the bass
- Amstrad Tower of Power
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- Location: NW Kent, Darn Sarf innit.
#7
shane wrote:Dave the bass wrote:No, that one's fine...shane wrote:You didn't mean that sort of bong did you ?
DTB
"The fat bourgeois and his doppelganger"