tubes...

[lookingforcool]

hey all....

can anyone tell me how to know for certain if i need to replace the tubes in my amp?

i have an old Legend Rock n Roll 50 Wicker face amp that just isn't as loud as i would expect from a 50 watt 112.

is it the tubes, or a deeper problem?

also, is it okay to replace the tubes myself (any special things i need to do, or just plug em in?) or should i take it to an amp repair shop?

thanks in advance!

.pete.

ps - i just got done cleaning pots and replacing fuses. it now turns on when i ask it to. and only half of the pots make scratchy noises when i touch them. that's a start. but now that it works, it's really noisy. i just don't know what bad tubes sound like.

pps - damn old amps and their weird ass switches. light's out in my power switch. radio shack has nothing even remotely close.

 

[bongolation]

Test your tubes on a tester. There should be some old one out on the floor for customer use at your electronics surplus junkstore or ham radio gear outlet.

Granted, these are probably not expertly calibrated and top-notch (they're usually forty years old), and they won't give you an indication of things like microphonics in your preamp tubes, but they will at least tell you if your tubes are in the ballpark of useability and if your power tubes - especially - are still within their useable life and relatively matched.

If you replace your power tubes, you generally should check the bias or have it done.

Your other tubes may be replaced without additional fiddling.

 

[Sonixx]

This can be several things...

Check output stage bias first...

If the amp is old, check Capacitors... either signal (usually in the output stage) or power supply filters (check these first).
It can be (probably output) tubes...

Got a rectifier tube check there...

 

[lookingforcool]

thanks guys for the replies. i actually ended up just getting really antsy and ran down to the tube amp shop. picked up some new pre-amp tubes (probably should've mentioned that it's a hybrid, only has pre-amp tubes.) thing works great now. i haven't heard this amp in years. now i remember why i bought it in the first place.

run a pair of p90's into it and crank. plus the master volume knob is screwed up, so it keeps going to 11 now. haha... doesn't actually get louder, but i promise. everything sounds better at 11.

thanks again.

.pete.