Tube amp newbie question

[Jamin]

Just picked up a Sig:X and have a couple questions about tube amps (before I break this one!) ...

When I brought it home, I plugged it into my old Marshall cab, which says it's 16 ohms...so, I plugged it into the 16 ohm output on the back of the amp. Played for probably 20-30 mins, fiddling with EQ settings and such...then suddenly noticing how hot this thing is running. I could feel the heat even on the knobs on the front panel, and the top vent above the power tubes was quite hot to the touch.

I immediately switched the power OFF. Realizing that my cab looks and probably is really really old, I suddenly considered the possibility that it might not actually be a 16 ohm cab (I got it used, and somewhere down the line someone could have opened it up, customized/altered it, screwed up it's insides, etc.)

How hot do tube amps generally get when running for a bit? If anyone out there owns a Sig:X, how hot should this amp get in particular? Also, would it be safer for me to just plug the cab into the 8 ohm output? From what I understand, I can run the amp into a cab with a higher impedance than it expects, but not a lower impedance? (ex. 8 ohm out to 16 ohm cab, but NOT the other way around?)

Also, once the amp got hot, I noticed a very quiet crackling noise...is this normal tube amp behavior? I really hope I didn't already break this thing

 

[Ryan-ZenGtr-]

Tube amps run really hot! They can burn you if you touch the tubes after it has been on sometime. It's normal... But keep looking for reassurance if you're worried, maybe something is wrong.

I *think* you're right about the impedance, but you'd have to check your owner's manual.

You're correct in thinking your cabinet may have been tampered with, as upgrading speakers is quite common, as stock, most cabinets don't come with a player's favourite speakers. Mine are Celestion Vintage 30's, which are in Mesa Rectifier cabs as standard. Have a look in your cab, maybe you got a bargain! Perhaps it has really nice speakers in it, worth a look.

 

[Jamin]

Thanks for the fast reply Ryan! I assumed all tube amps would run hot, and I read about people getting burned by them ...But in your experience, would you say that even the front control panel (EQ knobs, etc.) get warm after it's been running for a bit?

Also, I think I'll open up that cab tonight and see what I've got! Never know, I indeed might have gotten a bargain without knowing it.

EDIT: Opened it up, and a black wire is disconnected...hmmm...I'm guessing this might cause a problem with impedance? Don't think I got a bargain...plain looking, made for Marshall by Celestion. Time to get the soldering gun out...and google a Marshall cabinet wiring diagram.