Wiring for extension cabinets

I'm not familiar with that amp, but if your internal speakers are wired for 8ohm, then I would say wire the two epi cabs for 8ohms (same wiring as your two 16ohm internal speakers).

Then plug both 8ohm loads into the two 4ohm extension output jacks on your amp. I believe this makes the two 8ohm cabs run in series and become a 4ohm load presented to your 4ohm output. I run the same setup on my mesa DC-5. All my cabs and speakers are wired for 8ohm. When I use one it goes into the 8ohm jack. When I use two they both go into the two 4ohm jacks. This way I can run the 1x12 combo speaker, I can choose from two different 2x12 cabs, I can mix either 2x12 cab with the 1x12 combo speaker, or I can run both 2x12s for a half stack.

here is a hifi page that explains it pretty well.
http://www.bcae1.com/spkrmlti.htm

Hope this helps.

 

That's parallel, not series. Series would be a 16 ohm load. Just mod one of the cabinets to have 2 input jacks wired in parallel, and run 8 ohm output on the amp-cable-cabinet1-cabinet2. That would put an 8 ohm load on that output. Then, plug the internal 2x12 speaker in your combo into the other 8 ohm jack. That's assuming the 2x12 internal speakers are using one of your jacks, I'd figure they were. And, of course, assuming that those are 2 16 ohm speakers wired in parallel.

rooster.

 

Well, if the back panel says, "2x8" then it's a 4 ohm output with 2 jacks in parallel, I would think. I would say the best bet is to check with the owner's manual. It could be either 4 or 8 depending on how you look at it. Why they can't just label the total load on each pair of jacks is beyond me. Personally, I prefer just 2 output jacks with a good speaker selector that won't crap out. However, that can sometimes cost the manufacturer as much as $2-4, so I guess that's too much to spend for that component.

rooster.