'Ringing Tubes' in fender amp

harrisonmerwin

note: Fender Blues Deville Reissue (Tweed 410)

so i was playign, and noticed when i hit certain notes a ringing (almost like the salvation army bells) sound came out of my amp. I looked all over the place took it all apart, and eventually found out it was the pair of two little tubes that were ringing. I believe these are the preamp tubes. I also found that if i applied pressure upwards (towards the seat of them) the ringing was lessened or diminished. It is also only ringing on the clean channel, if its on the overdrive channel, the tubes seem to be inactive. If i flick the tubes while active in the clean channel, the same sound happens. So i believe it is from vibrations. They come with a 3/4 inch pecie of fitted foam around the two of them, but it doesn't seem to dampen the vibrations enough.

Any thoughts on how to eliminate this ring? is it the loose seats? new tubes? better foam dampening?

happy holidays,
Harrison

lucylespian

Sounds like they might be getting microphonic, happens as they age. Are they pre-amp tubes, or is it the driver tube ? DRiver tubes do teh most work, so wear out with the power tubes, but pre-amp tubes last a lot longer.

enharmonic

an easy test.

Fire up the amp. Let it get warm, then turn on the speakers if you have a standby switch. Next, tap the preamp tubes with a pencil. If you can hear them though your amp, they have gone microphonic and should be replaced.

MichaelMcKevin

enharmonic wrote:

an easy test.

Fire up the amp. Let it get warm, then turn on the speakers if you have a standby switch. Next, tap the preamp tubes with a pencil. If you can hear them though your amp, they have gone microphonic and should be replaced.

you fit too much knowledge in that head of yours. eventually when i get some gear, i'm just gonna search up your old posts if i'm having any trouble with it.

lucylespian

I was reading my Boogie manual about this last night. They definitely sound microphonic. Randy says it is normal for them to ring when not turned on though. If it is the driver tube, ringing is less common, you get either scratching or your whole amp just sounds shit. Just replace them one at time with a new good tube till you fix the problem.

harrisonmerwin

yeah they definately ring that way....its funny because i bought the amp, out of the box new from a music store in late october. what does microphonic mean by the way, and can i simply get a batch of tubes and do a replace, or is biasing involved?

exhausted

http://studentweb.eku.edu/justin_holton/tubes.html#i2

biasing isn't involved unless the power tubes are being replaced and the amp isn't self-biasing.

lucylespian

harrisonmerwin wrote:

yeah they definately ring that way....its funny because i bought the amp, out of the box new from a music store in late october. what does microphonic mean by the way, and can i simply get a batch of tubes and do a replace, or is biasing involved?

There is a few pages on this topic in my printed Lonestar manual, which is probably re-produced in the On-line version which are downloadable. Whether you like Boogie or not does not matter, the info there is good.
Basically he says to narrow it down to wchich ever channel, which it sounds like you have, tehn replace each tube one at a time, using a new good tube to replace them, making sure you put each one back in it's original socket.

There is a lot of good info there, talks about biasing and dispels a few myths, also has a neat story descibing how tubes are designed while involving Irishmen and bars. Good reading for any tube amp owner. Also lots of good stuff about speaker wiring, and how to choose which output socket to connect to, and what to do if impedances don't match.
Lots of people bag the Boogie manuals for being too big, but ya can't know too much in this life and compared to my H&K one which basically says " there are a bunch of knobs to play with", they are great, and can be adapted to most other amps. I know you have a Fender, but I am not brand jealous, and Boogies are really modifed Bassman amps at heart anyway.
Did you know Randall Smith learnt how to build ham radios from the son of the guy who invented the STilson wrench, and who was buildiing control panels for nuclear subs in teh same workshop ??