I have a b52 at100 2:12 combo. I also have a splawn 4:12 cab. The at100 has two speaker outputs. And has a switch for 4/8/16 ohm's. All The speakers are 16 ohm's. does anyone know what position the switch should be set in to run the combo's speakers and the 4:12 at the same time?
Any help would be appreciated...
First you need to find out if the internal speakers are automatically disconnected if a cab is plugged in.

Also double check that the amp speakers are wired in parallel for an 8 ohm load total.

If you were to just run the 4x12 cab and NOT the 2x12 then match at 16. I would just do this. No reason to run all 6 speakers anyway is there?

Whatever you do match match match. If not sure - don't do it.

Also, this thread has interest to me. Please post a clip.
I do have to manually unplug the two speakers from the back of the unit. It's just a male 1/4 in. Jack wired to the speakers, and then plugged into one of the two speaker outs. So it has no automatic disconnect. The at100 combo has The exact same schematic as the at100 head. So it's basically just the at100 head unit in a 2:12 combo box.

Im not at home right now, otherwise I'd have all the little details on hand. I have the head version and the combo. I run the head into an avatar with two vintage 30's and two g12 T's in an X pattern, like the bogner ubercabs have. That setup sounds great! This setup is for a different band than the one I just joined.

Im wanting to run my at100 combo with my splawn cab,(same speaker setup as my avatar). And also run the two 12's in the combo(2 eminence legends) just to see how the combination of those speakers would sound together.

Either way, Im very impressed with the b52 at100, head or combo. Both sound very good. They're value far exceeds they're pricetags. In my opinion.
I'll put up some clips of the different combinations later today or tomorrow.
Thanks for the help.
Last edited by Maximo33 at Jan 13, 2012,
I see.

Well if you are positive that you can run the internal combo speakers AND an external cab at the same time then this is what I'm thinking (you may want to get this validated).

The 2 speakers in the combo are probably wired in parallel for an 8 ohm load total as mentioned. 16 + 16 wired in parallel = 8 ohms.

If this is true, then you will only want to add an extension cab that is also 8 ohms.

Additionally, as with most amps, your B52 will want to consider both loads (internal speakers and ext cab) as a parallel load meaning you would then set your amp to 4 ohms.

8 + 8 wired in parallel = 4 ohms

(FYI in series wiring you add up so 8 + 8 would = 16.)

Now, your Splawn cab is probably wired in series/parallel for a 16 ohm load total. That is pretty common. Series/parallel means 2 sets of the 16 ohm speakers are wired in parallel for a total of 8 and then those two sets are wired in series so you are back to a total of 16 overall. (see below)

If this is true, then you won't be able to do what you want to do. However, if you ext cab has stereo capability and one half of the cab has its own jack at 8 ohms total then you could do that but it would only be 2 of the 4 speakers.

Does this make any sense? Good luck.

(PS - I really dug the B52 ATX head I played at GC)

Everyone is entitled to an opinion.

Feel free to express yours so I can make an informed judgement about how stupid you are.