2. amps-preamps
  3. 1336871056

12AX7 preamp tube failure last night

I was playing a gig last night with my Vox AD50VT amp which has one 12AX7 preamp tube. Suddenly I lost all sound. Is that a normal failure mode for a tube? Is that uncommon? I bought this amp new almost 7 years ago and love the sound of it. I have a recording of the song when it failed and it seems like you can hear the tone breaking up and getting scratchy right before all sound was lost. Any ideas appreciated.

Bill
notserp300

Showing 1 response by mcintech

mcintech
128 posts
 
May I also recommend allowing the amp to cool down before moving it, the tube filaments are at their weakest when transitioning from hot to cold or vice versa. I have seen most tubes fail DURING use if the amp was bumped or slammed whilst it was on, especially large triodes like 845, 211's.

I used to emphasize with my Nagra VPA customers to NEVER move them when on or cooling down.
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