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
mozartfan
2,143 posts
 
Gold Lion KT88's

Tried em, return them, 
Went with Sve 6550,  nicee upgrade over GL. read  somewhere  on the INet another audiophile same reaction,,but hey, maybe your system is dif, 
,,back to OP, yes 1 power tube is going bad. 
Sve's 6550's built like tanks to last. 
These are musical power tubes. 
mozartfan
2,143 posts
 
primaluna supplies sino shuguang tubes labelled primaluna

Well this bit of testimony sure helps, 
IMHO, chinese tubes  are not as reliable as russian ,, sure Psvane hates to hear this, but its true. 
Russia makes superior quality.  and of all russian power tubes Svets 6550 are my favorite , EH's are my 2nd choice. 

billtro OP
12 posts
 
Well Mozartfan, that was pretty prophetic.  I reinstalled the fat boys and the noise stopped after 2 minutes.  Ran the amp overnight and found one PL red light on.  So yep, a tube was going south fast.

 
atmasphere's avatar
atmasphere
11,793 posts
 
Anytime you change something and a problem shows up, its a good bet that the thing you changed has something to do with it.
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