Ok, I have two seperate questions. 1) Why is it that a Marshall 4x12 can run at 16 ohms mono, 4 ohms mono, or 8 ohms stereo? I think the speakers are 16 ohms a piece, and that would explain the 4 ohms mono, and 8 ohms stereo part, but where does the 16 ohms mono come into play? Is it a way of running in series, or am i just way off. I guess I just never got it. Also, why don't we see this on Bass Cabs? Couldn't you run a 4 ohm 4x10 at 4 ohm, or 16ohms? Why is a better question, but COULD you do it? 2) The Ampeg 6x10 is a 4 ohm cabinet. If all of the speakers are 32 ohms, it would be 12 ohms, right? If all of the speakers were 16 ohms, it would be 6 ohms, right? If you had some of one, and some of the other, wouldn't you run certian speakers heavier than the others? Yet another thing that always confused me. Any insight into these mysteries of resistance would be wonderful. Thanks.

16 ohms? Easy. You put 2 speakers in parallel -> 8 ohms Do it again. Another 8 ohms Put them in series -> 8 + 8 = 16.

#1 - I think the first post answered the "how do you do it" part. Bass cabs could do it too, but nobody wants a 16 ohm bass cab because most folks run solid state and the lower the impedance the more power you get. With tube amps, you can get full power into a 16 ohm cab or 4 ohm cab (assuming it has taps for both of those, which most do). #2 Not familiar with the Ampeg 6x10, but they would have to each be 24 ohm speakers to hook up in parallel to get 24/6 =4. Any way you slice it, they are going to have to be weird speaker impedances, not 4 or 8 or even 16 or 32 ohms. You don't mean the 8x10 do you? Those are filled with (8) 32 ohm speakers for 32/8 = 4 ohms. They could just be fudging the numbers and it's really a 5.3 Ohm cab (32/6 = 5.3)? I don't know. Chris