Okay, sorry if this is a stupid question. I have a Peavey Duel 212, with a terrible aftermarket 15" speaker inside. I prefer the sound of closed back cabs anyway (it's an open back), and I found a good deal on a 4x12 loaded with Vintage 30s. The combo is switchable between 4, 8, and 16 ohms, BUT it has two outputs (one for each of the original speakers). This 4x12 cab is also switchable (4 or 16 ohms). I want to run it in mono, and plug it into one of the outputs on my combo amp and leave the other one empty. What do I set the amp to run at? If I set it at 16 ohms, is that putting out 16 for each output, or 8 for each, or what? Should it be at 8 and the cab at 4?

Side question: if I just match impedance straight across, should I run it at 4 ohms or 16? Will it make a difference?
The impedance on a valve amp MUST be matched at all times! As far as I know it says "4 Ohm min speaker jacks paralleled" on the back. That means that you can switch your cab to mono either 4 or 16 ohms then set the impedance switch on the amp respectively and plug the cab in one of the outputs (doesn't matter which one).

Side answer: Basically it doesn't, but it *might*. I'd try and see if there is a difference.
Last edited by Ace Carson at May 20, 2011,