Alright, so I just recently bought an Ampeg B-25B stack. Or...at least I think it is. I know the cab is because it says so...but the Amp head itself just says B-25. Will a B-25B say "B-25B"?
That's my first question. I was also trying to date the thing and find out if it is all-original. The serial on it is 005751. I've learned many times that's not enough, and I don't wanna open it up and light myself on fire so I put pics up to show the chassis and back. It's got two 12AX7 tubes, a 7719, 2 7027A's, and 5AR4 - if that helps any. It looks all original to me (minus tubes of course), but the Polarity and Power switches on front are plastic so I was wondering.
Also, I posted a thread a few days ago asking anyone if they knew the impedance of B-25 heads. I learned it was probably 16ohm/8ohm a while ago but cannot find any visible label to tell me that. I was saying before that I began using it when I got it with an SVT15E I regularly use (rated at 8 ohms) because it's a much lighter cab than the B-25B that came with the head. I have read you can mod it to run at 8 ohms but it normally runs at 16. However, I also read you can plug a dummy jack into the extension speaker and imitate a cab there and bring it down to 8 ohms. However, it only has the Ext. Speaker to plug in at all, due to the fact that (as I pictured) there is an plug coming out of the amp in place of the hum-balance speaker plug. I have seen pics of these heads with an open plug in place of this, but I don't know if that's a mod. These are the only speaker jacks I know of. Does that plug automatically act as a dummy jack? I wondered this because I am forced to plug into the extension right now with my SVT15E.
Needless to say, my Bassman runs far hotter than this head, and I thought that bad impedance matches would run the head hotter. So, I have a laundry list of things to know. I figured I'd try to get them all in one sitting.