The AM Forum

Are there any vibration isolation pads or feet that work for 60 Hz (or is it 120 Hz) vibration?

I feed my old gear with the most beautiful AC you can imagine from an Elgar 6000B AC line conditioner.  The AC voltage varies here from 117 to 126 but the Elgar gives the 50 year old stuff the most beautiful 115 V you've ever seen, +/- .025%, 20 uS response time, not to mention < 2% harmonic distortion.   Talk about overkill.

But it does hum.  It sits on a lower shelf connected to the operating desk, a built-in affair that has this compartment intended for a printer.   The Elgar uses the desk as a resonator.   I would like to isolate it from the desk to reduce the hum.

Any good feet?  It weighs a lot, 65 lbs courtesy of the iron inside.

hmmmm   ... sounds like ferro-resonant technology ... quite good at making audible hum ... see if you can find some vibrasorb ... this was (a few years ago) rubber laminated to cork sheets and around an inch thick ... good for this purpose ...73 ...John

Try a few old mouse pads.

Thanks guys.  I think I'll look for the vibrasorb.

Jon

Put it in a carpeted floor.   I know a guy who put one in another room so he would not hear it hum.

Go to Orion telescope's website or similar.  Celestron, Orion, several others sell liquid filled vibration dampners for telescope mounting isolation from tube and wind vibration, passing traffic vibration, etc.  Come in sets of three though  ;D  (for tripods.)    Maybe you can buy four, heh, heh.
They are miraculous on long period vibration isolation  (read, audio bass for our purposes.)  Probably will work for higher freqs. too.

So you can tell what they look like here's a link to a random (British) page.
http://www.scsastro.co.uk/it030065.htm (http://www.scsastro.co.uk/it030065.htm)

I think hi-fi stores sell liquid filled vibration pads too.  Maybe even in sets of four.

You could always use some Mini-Clouds.

(http://www.gingkoaudio.com/images/miniCloud.gif)

tennis balls?

Three small inner tubes, inflatable, from a small implement tire, with a non-resonant surface on top to support the huummy unit are almost as good at isolation as an electron microscope or optical table... if you really want a non-resonant surface, make a sandbox to sit on the tubes.

Buy USA made tubes unless you want them to leak.

           _-_-

Do you have a picture of the regulator's insides? I'm interested in such thigs fro a technical standpoint.

I have some 6.6KVA ones that do not hum. They are stepper driven variacs controlling a small buckboost transformer and aso have very low distortion. Also a pair of GE 200A 120V ones that use an induction winding to buck or boost the line. Old buzzard controllers with those :)

otoh,you might want to first open up the beast and mount the transformer on some rubber blocks inside the box... remove the screws and put a rubber block either under each foot or under the entire core... if it is under just the feet, you'll likely want a big fender washer between the foot and the lower rubber block, then another rubber bit on top plus a washer to suit placing the foot in a sandwich of rubber... that will reduce the condution substantially, probably good for ~20db or so reduction.

Maybe not enough, but something...

      _-_-bear

big silicon rubber o-rings might help that proposal also. tru-value hardware stores sell 1/4" silicon rubber in 4x4" sheets. Enough could be cut into squares to do well.