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Hi pitched hum from TT pre-amp?

Hello,

I have a Sonic Frontiers SFP-1 pre-amp. My rig is a Scoutmaster table and a Benz Micro Glider (MC). While playing a record last night, between songs I heard a relatively hi-pitched tone; probably a bit below the 1 Kilohertz frequency (test tone). I gently tapped the top of the TT pre-amp and the tone stopped! The pre-amp contains 4 tubes; two Sovtek 6922's and two 12AT7A's. Do you think I have a tube on its way out?

Any feedback would be welcomed.
judsauce

Showing 3 responses by atmasphere

atmasphere's avatar
atmasphere
11,637 posts
 
Sounds like your tubes are likely shot.
atmasphere's avatar
atmasphere
11,637 posts
 
The complaint sounds like a microphonic tube.
atmasphere's avatar
atmasphere
11,637 posts
 
If its a loose tube you will get a crackle and possible loss of signal. OTOH a microphonic tube can 'sing' (whistle, whatever you want to call it) and often responds or stops when tapped or subjected to vibration. Such tubes won't sound their best either.
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