HedonismBot wrote: ↑Thu Jul 07, 2022 7:35 am
Update: turns out, the local guy has retired. The closest (reputable) alternative is an hour drive away and happens to be Skip Simmons who is a proponent of an “as long as everything works, keep it original” philosophy. Called him yesterday and it sounded like he was talking me out of taking any immediate action. He recommended that, if I must swap out the speaker, I replace it with an Eminence Legend 15, which I did order. I don’t see why I couldn’t change the speaker by myself so I guess I’ll do that and save some money on gas and labor. I’ll keep you posted.
That sounds... frustrating.
I mean, good luck with the speaker, I have no doubt you can take care of that yourself.
But as far as not changing anything... huh?
So, I'm super new to my amp tech education. I know enough to know I barely know anything. I only have basic, limited understanding. But I was in a similar situation over the last year. And reading a lot and trying to learn about amp maintenance basics only reinforced what other more experienced players told me when I asked around here last year. If that bias cap goes, so go the tubes and maybe the transformer.
I looked at the invoice for the maintenance I just got last month. It was for *four* capacitors, totalling ten dollars. The ones I got replaced were identical to those white Mallory caps in yours, my photos are still up in that thread. Your amp appears to have a fifth cap (the big metal-can one near the transformer) in the bias balance circuit. I don't know about the metal ones, but they seem like they could be original.
And I have to imagine the filter caps underneath are probably original if everything else is. So, altogether, that's, what... ten capacitors? Maybe $50 in common parts?
So, whatever their reputation might be, I find this person's diagnosis very suspect. If even *I* understand that electrolytic caps have a limited life span before they dry up, and that the failure of a CBS-era component purchased for the fewest cents -- and rated for what, twenty years? -- could knock out the whole amp, WTF is this person's problem with preventative maintenance? Why wouldn't they want an easy single hour of bench work money? Do they want you to ruin your amp so they can charge for a rebuild?
The Bantam Bass is awesome and a really cool, unique thing to have. I'm happy for you and jealous I don't have one. I adore these weird early-'70s oddballs.
But some tech treating it like it's a blonde Showman is insane, especially if it risks taking out the amp, even without audible symptoms.
Sorry, your plight really got me pissed off. Maybe some nearby forumite can help, and I really hope you can find somebody to safeguard that cool amp for you.
[P.S. - Like I said, I'm new to the technical side of amps, so take anything I'm saying with a grain of salt, ask people smarter than I am. But read my Bassman Ten thread here or find my posts on TGP and let their advice about the bias cap speak for itself.]