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
billtro OP
12 posts
 
Thanks for the reply's.  I'll try cleaning the tubes and see what happens.  Next time I'll look for the red indicating lights.  In the end, lesson learned on audio tube suppliers!  Thanks for the leads guys, very helpful.
millercarbon's avatar
millercarbon
12,531 posts
 
Many tubes have a small amount of gas or material inside, forget what they call it but its to facilitate electron transfer. This material can condense in different places when the tube is cold. Then as the tube warms up as the little bits turn back into gas or fly off in little pieces they of course go from electrode to anode and upon hitting the anode create a little voltage surge which we hear as a pop or click or static. 

Eventually this all settles down. Usually. We hope. Welcome to the wonderful world of valve amplification.
billtro OP
12 posts
 
Thanks millercarbon.  I've been also told that I may just be hearing some noise from the new tubes warming up for the first time and they'll settle in over the next 100 hours.  We'll see and thanks for the welcome. I'll report back in a couple of days.

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. 

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