Vibration Control [message #91382] |
Tue, 28 January 2020 09:56 |
Barryso
Messages: 203 Registered: May 2009
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Master |
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This is an odd one. Chalk it up to being semi retired, bored and having a lot of scrap shower pan liner. The liner is left over from making gaskets for the 4 pi woofers and horns.
Last year I put together the Whammy headphone amp as a preamp. It's an inexpensive kit available on the DIYAudio website, designed by Wayne Colburn of Pass Labs, and it's a very good unit for very little money.
There's supposed to be a chassis available but that hasn't happened yet. So the circuit board has long computer motherboad standoffs holding it up on a piece of baltic birch.
When it first got put together I figured there should be isolation between the birch and the standoffs. So I put folded paper towel pieces between the standoffs and the birch ... but got indifferent results. It changed the sound but it wasn't definitively better. Gave up on it.
Well after making gaskets for the 4 pi's there was a great deal of scrap ... so it was time to futz. Cut some squares to put between the Whammy standoffs and the wood, gave it a listen and thought it to be an improvement. It was modest but when you removed it you could clearly hear it's absence.
Added another layer of squares and it changed again ... and adding more layers changed it a bit more. The presentation with layers of shower pan liner is clearer and it's removed a bit of smearing.
Listened for a week and have to admit I was pretty pleased with myself.
Next up, a DIY tube preamp. It has the brackets for the tube board in direct contact with the steel chassis so it seemed reasonable to try the same magic shower pan liner between the chassis and the brackets.
Yup, cleaned up a bit of grunge. Guess vibration control makes more sense on a tube preamp than a solid state but it's clearly audible on both units. The tube preamp got built about 20 years ago and it never occurred to me to attack vibration in the chassis. Had used a lot of inexpensive things under the chassis, some of which sounded good, but never did anything internally.
Shazam!
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Re: Vibration Control [message #91389 is a reply to message #91382] |
Thu, 30 January 2020 07:49 |
johnnycamp5
Messages: 354 Registered: June 2015 Location: NJ
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Grand Master |
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Hello Barry good job.
I hope your enjoying the 4Pi's!
I too built the Whammy and put it in their suggested (cheap) chassis...I forget which brand and model off hand.
The pcb slides in the chassis's long grooves, so It doesn't really get screwed in hard or solid, nor is it damped.
When I move or shake it doesn't seem to rattle or clank around though, I think once the face plate is installed, the pcb is pushed into the back plate holding it secure.
I also built the Forewatt preamp from Oddwatt Audio, which I enjoy much, much more, so I haven't really fussed with the Whammy too much since finishing it.
As far as tube micro-phonics, the new kt 120's do it too...at least mine did.
The first matched quad I ordered (for use on odd blocks) were bad enough to hear even without tapping the tubes or amps, so I had to send them back.
The next quad was micro-phonic when tapping the tubes, but not while sitting only powered on (like the first quad).
I haven't heard the new tubes be a problem at higher volumes (perhaps they are)... the mono blocks are sitting on the concrete floor slab.
I should note that the matched quad KT88's I ordered with the OddWatt amp kits have (almost) no micro-phonics while tapping the tubes.
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