Bassman 10 As a Bass Amp... no really.

[tyrebyter]

I picked up a fender Bassman 10 because I always wanted one. Some tired components needed replacing, like the electrolytic caps. While it makes a fine guitar amp, it's a little soft for bass. It had the original bargain basement Utah 10" drivers and they were barely passable new, so they got shelved for some Eminence BP102's. That was a big help. While in the amp replacing the caps, the power supply diodes were taunting me so they got replaced with some fast recovery diodes. The ouput transformer was almost big enough for a Princeton but the nice thing about the BM 10 is the vast real estate to work with. New output tranny and bias adjustment tightened things up nicely.
Here's the problem: The plate voltage on the output tubes is 517 volts! Holy cow! And I'm getting just over 500 at the screens. Anybody deal with this before? I'm considering going to a tube rectifier just to get the voltage down, but there goes the tight bottom end. Any ideas?

 

[T-Bird]

Hi.

Welcome to TalkBass tyrebyter.

When I bought mine (amp only) back in the late 80's I didn't do much more than replace the fuse sockets.

Unfortunately the bloke who sold it to me kept the cab as it made "a cool keyboard stand" . I even tried to swap it for a real KBD stand with no luck.

I ended up doing a Gibsonish 2*12" open back particle board cab for it and used it mainly for guitar. Used may be a bit strong word as a 30mm particle board weighs just a little more than what's comfortable . Sometimes I played bass through it and the sound was fine with the square magnet Fender speakers I put in there.

Is Your heater voltage spot on? If it's not, is it possible that You have an export model and the PT primary is incorrectly connected?

Regards
Sam

 

[Tusec]

Wow, 512v, that's pretty hot. My '67 Bassman is at 460 I think. As long as the plates don't have red hot spots you should be fine. If you replace the tubes I'd probably use good NOS. They would probably be happier at that voltage than Chinese cheapies. A tube rectifier would sag on low notes which is probably not what you want for bass.

I'm surprised the output transformer is small. Is it the original? My Bassman's is massive, as is the case with other Bassmans I've seen.