: Hey all,
: I got a concert bass head awhile back, and for some reason I'm getting a little fuzziness in the sound. It's more like a white noise fuzz than an overdriven/distortion type of noise. The amp is from '74 (it's as old as me!) - is there anything that I should check out - something that might commonly wear out - capacitors or anything?
I know exactly the kind of noise/fuzz you mean. The common cause is a loose/intermittent type connection.
Check the jacks... the ones that internally connect the preamp/poweramp together and give you a power amp in, preamp out on the back of the head. Some crud could have built up on the switching contact. A couple swipes with emery cloth on both sides of the contact.
Play your bass plugged into the power amp in jack. The output will be lower, but you should be able to hear if you still have the fizz. If not then the problem is isolated to the preamp board.
These amps use wire contacts instead of soldered joints and any one of them could have dirt or corrosion. Pull each one off (one at a time, so you don't lose track of where they go) checking for a firm contact.
Finally, a transistor could have worked itself lose in a socket. These amps are really neat for using sockets for all the transistors. Press each one lightly with a finger and wiggle it. Don't take one out unless you are confident you'll be able to get it back correctly.
If all else fails, take it to a tech with a scope. These types of problems really need a scope for signal tracking.
Hope this helps!