2. amps-preamps
  3. 1369076228

Tube pre picking up feedback/vibration?

Recently got a pair of Magnepan 3.7's and a Sanders Magtech.
Have an old ARC LS15, newly retuned.
Have noticed a muddiness in the bass, kind of a one tone bass at times. When I tap on the preamp cabinet, get a distinct sound transmitting to the speakers, so
I gather I'm picking up some feedback. The pre is rather cole to the speakers, and it doesn't have the isolation of more current models.
Can you guys help with suggestions to stop this?
I'm considering a new preamp, but never noticed this with my previous speakers.
Are there isolation devices to deal with this, tub dampers, etc???
Changes the wires from the Pre to the amp, Putting in my Verbatim wires in place of the Nordost, and that helped some. but want to remove this source of pollution from the system, obviously.
Thanks
Carl
brrgrr

Showing 1 response by p59teitel

p59teitel
312 posts
 
"Sorry to say, all tubes are microphonic, at least to some degree; there simply isn't such a thing as a non-microphonic tube."

True enough. But to find the most microphonic and thus problematic tube, lightly tapping each tube as Rrog suggests will help you isolate the bad boy so you can replace it with a new one. Just make sure you have the volume set at a low level when you do it.
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