Peavey 6505+ - noise from hell !?

[Gary87]

Hello ! I must say that english is not my first language so be aware

I've got my 6505+ for about 3-4 years , no problems so far. I changed the power tubes last years but I have not abused them. I used this amp for about ... 20 hours at low volumes since I changed the tubes. Preamp tubes are stock, I only changed PI to Sovtek LPS.
Today I noticed that when I'm turning amp off (first standby then power switch) I can hear quiet fart(or some king of dive bomb sound , it varies) FROM SPEAKER. The sound is quiet, but noticeable in quiet enviroment. Faulty preamp, power tube or what ? I don't remember this "error" previously, maybe I haven't noticd it before. Beside this - amp is playing perfectly, zero other issues.

Anyone ?

 

[Racerxrated]

Probably a preamp tube. Grab another pre tube and swap it in/out of each pre slot and see if you can identify which pre tube it is.

 

[Gary87]

Thanks

I changed the outlet and ... well , it's ok now. We will see , maybe the outlet is the culprit or preamp tube as you said.

 

[southpark tube lab]

the sound you are hearing is a drop in voltage . in the power section.i think some stand by switchs are noisey