Older 6A5Q version. The original CTS(?) is kaput. It's very not BF/SF sounding, IMO. I had pretty good luck with a cheap MOD 12-35 in the multivox in my avatar. The MMB sounds similar, with less low end due to cab design, methinks. I tried it with a C12N, and it was good, but way too loud. And still didn't help much with low end, but the amp is what it is. The MOD 12-35 is way less efficient, and I would prefer something like that. I don't see myself gigging much with this amp, if at all. Before I plunge for the MOD, gimme some suggestions. Nothing over, say, $125 w/discounts. But I would prefer to keep under $100. And, please, for the sake of all that is holy, remember to party on.