2. amps-preamps
  3. 1207684029

Noise upon pre-amp tube replacement

I was replacing 7308 and 12AU7 tubes today (pair by pair) with newly purchased NOS tubes. They are RCA 7308 gold pins (made by Siemens) and Raytheon 5814. Each time I replaced the tubes, after 5 minutes I heard a "thump" from the left speaker as if a brick or wooden board fell down on the floor. I am wondering what it was? Has anyone experienced such phenomenon? My amp definitely does not like frequent tube rolling!
transl
transl OP
156 posts
 
It was a single "thump" but then everything worked OK. There was no need even to swap the tubes from side to side.
atmasphere's avatar
atmasphere
11,841 posts
 
Did you have the amplifier on while you were replacing the tubes in the preamp? The thump could have been the preamp warming up, if so then there are no worries- just make sure you turn the preamp on before the power amp(s).
transl OP
156 posts
 
This is an integrated amp. This problem did not appear again.
cruz123
586 posts
 
Transl, I had the identical problem a few months back. I would turn on my amp (Cary SLI80) and within a few minutes I would get the thump - identical to your scenario. After about a month of this behavior, one of my power tubes failed. I would swap out all the tubes one by one in the channel that's creating the noise until you find the bad tube.
transl OP
156 posts
 
Hi Cruz,

I have the Cary SLI-80 but I've never had a problem like yours, save for burnt fuses a couple of times.
More to discover