New Tubes For My 1968 Bassman?

[applefan76]

I have a 1968 Fender Bassman with blackfaced circuitry. I think that it still has original RCA(?) tubes. I also notice a slight hissing noise whenever I play it. Should I change the power and preamp tubes to get less gain or is there something else that I can do?

Thanks,
Kyle

[iiipopes]

Possibly. The hissing could be the filter caps going bad. Filter cap replacement after a few decades is a common repair. I've done it myself on my '69 Bassman Export (Bassman with the multi-tap transformer for overseas use)

Electro-Harmonix is importing some great tubes. I use their low-noise 12AX7's for most of my preamp applications. That, or you can get NOS (with a $$ price tag to match) at thetubestore.com .

[Staccato]

Doug at Doug's Tubes will give you the personal service that you deserve at very competitive prices.

Call him on the phone, and give him the model and list of what tubes are in it, if you can.

[beans-on-toast]

Originally Posted by applefan76

I notice a slight hissing noise whenever I play it.

Everybody wants to be a critic. Look in the back to see if there's a snake hiding in your amp.

The easiest thing to try is to check out the tubes. I would start by swapping out the first preamp tube and work down the line to the power tubes. A hiss is one of the signs that a tube is wearing out.

There are many other possibilities with an amp of that age. It would be a good idea to have a tech look at the amp and perform any maintenance that it needs.

[iiipopes]

And upgrade it to a 3-prong plug if it isn't already.

[christw]

A good tech around here will usually charge you a $40 to $60 diagnostic fee and apply that cost towards whatever work needs done or parts need replaced. Seems like a good plan to me.

[johnk_10]

weak or bad filter caps do not hiss. they hum. nor does the AC cord. all amps have some hiss, but if your's is more than normal, the first thing to check are the preamp tubes.