Ok so i looked through the forum and couldn't really find the answer to my question.

I recently bought a '68 YBA-1 and i'm having some work done on it at a local shop, while i was in there i talked to the guy and asked him if he could change the 8 ohm speaker output on the head to 16 ohm since the marshall mono 4x12 cab i have is 16 ohms. He looked at the schematics for the amp and said the only way i could do this was to replace the transformer. He then said i could rewire the marshall cab from 16 ohm to 4 ohm, and that it would be safer to run the 8 ohm traynor into a 4 ohm load instead of 8 into 16. The guy knows what he is talking about and knows a lot about older fender amps, but the idea of an 8 ohm head into 4 ohms just sounds backwards from what i've heard in the past.

also the amps has an output marked speaker and an output marked EXT. what is the ext? Is it just another speaker out?

any ideas?

that amp will drive a 4ohm or 16ohm cabinet no problem. neither will sound exactly as the amp was intended to sound, but either will work. if you want to have a perfect impedance match, have your guy wire the 4x12" so only two of the speakers are hooked up. that'll get you 8ohms and a little less output volume, which means you can crank the amp up more.

the ext speaker jack is just an external speaker jack, so you can hook up two cabs at the same time. though the jacks are wired in parallel, the ext speaker jack is only live when there's something plugged into the primary speaker jack. don't make the mistake of plugging a single cab into the ext speaker jack and nothing into the main speaker out. basically, always use the main jack which is the one on your right when you look at the amp from the rear.

great amp.

yeah I didn't even think of wiring only 2 of them in parrell. scott what do you think would be safer running it at 16 or 4. I've heard both from people. I've heard that 16 would be safe cause the amp won't run as hot, but I've also heard that it could damage the amp cause its not enough of a load. I've heard that 4 would be better cause the amp runs hotter and its better to "bog" the amp down. but I've also heard that I could blow a transformer this way. thanks for the help.

I'd run it at 4. I've run my YBA-1A with a 4ohm cabinet for many many months and it doesn't care. The transformers in the 60's Traynors are as robust and "unbreakable" as you're gonna find in any musical instrument amp, ever.

I've also run a YBA-1 with a 2ohm load for an hour or so, and it didn't freak out.

Some people say lower is better, or higher is better, but from what I understand, it's better to use a cab with a lower impedance than the amp is looking for because going the other way around, that's where you can blow the transformer. From what I've heard, read, and experienced, the old Traynors don't much care about speaker load, and it's safe to go half or double and you don't have to worry. I've never blown a transformer in a Traynor.