2. amps-preamps
  3. 159667-150309

Tube amp crackle noise with pre-amp volume at zero.

I changed out some stock EL 34s with a brand x on my prima luna Dialogue HP amp. Within seconds of powering up the amp with the pre-amp volume all the way down, I herd a crackle like noise from the speaker.  It was somewhat intermittent and random between the two speakers.  I shut it down, checked all connections, and started again with the same results.

I returned the stock tubes and everything is normal.  What happened?  I didn't have the guts to increase the pre-amp output! Tube microphonics? (spelling?) 
billtro

Showing 1 response by rshak

rshak
416 posts
 
billtro -I also own a PrimaLuna (DiaLogue Premium Integrated). This amp has the "Bad Tube Indicator* feature that puts the unit into protective mode when a power tube goes bad and tells you which tube is the culprit.

This feature has proven its worth twice.  The first time was a little over a year and a half ago when the #1 KT88 failed. The second time was a couple of days ago when the amp shut down and the BTI showed a bad KT88 in the #4 slot.  

I did notice some sporadic crackling/small pops before each failure.  So, if your PL has this feature, you can rest a bit easier knowing that the BTI circuit will kick in a shut down the amp before any damage is done.

I've ordered a new set of Gold Lion KT88's which should arrive on Monday.  
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