AmpTalk.com

[JoEllis]

I bought an early 70's Super Bass 100w head, with a 2X12 cab (4ohms), from a pawn shop about 6 years ago (deal of a lifetime!!!). The amp had a mains cable attached, which was obviously added later, and the mains- and impedance-selectors were missing. Back then I didn't really know anything about tube amps other than I wanted one.

Everything sounded fine, but the output transformer blew about 2 years later. I had it rewired and it has been running perfectly (or so I believe) since and it sounds GREAT!!!! I *think* the output-transformer was rewired to run at 4ohms.

My question is this: Would it be OK if I rewire the 2X12 to run at 16ohms and then hook up another cab to the amp to run it as a full stack? Plus: I would have known by now if anything was wrong, right?

Sorry if my questions seem stupid. I'm only learning about this stuff now.

[Goes_To_Eleven]

I'd suggest that you take the head to a tech and have him go over it to determine where the impedance is set, and maybe have it restored to the normal selectable setup. It's not a good idea to run a 4 ohm & 16 ohm cab together. If the amp is set at 4 ohms, you'd want two 8-ohm cabs running in stereo. Otherwise, you may run into trouble with mismatched impedance.

[JoEllis]

Hey, thanks for the reply! Just came back from a 2-week tour tonight (drove 15 hours today!!!). I'm having her checked out by a tech in about a week's time. She needs new output-tubes and just basically a good service, cause this is my workhorse amp. I'll have him check it out. Played through her on the tour and she blew everything else away. I'll probably keep her as is for now if the tech says everything is cool. Not sure that you can find those old selectors anymore. Maybe I'll get her re-wired to original standard when clubs actually start paying me what they promise Anyway, I was just curious about adding more cabs.