Speaker Area and Volume

It's almost impossible to give any accurate answer. Firstly, it's unlikely that you'll find speakers of different sizes with the same efficiency (which itself has the area factored in, since it's measured by putting sound through the speaker), and secondly the different frequency responses make the apparent loudness vary, especially in a mix. Not only that, cabinet design matters too.

As a very general rule, I tend to think of a 2x10" as being around the same volume as a 1x12", with a 1x15" being slightly louder. But all other things being equal, the 2x10" will most likely cut through the mix better.

A 2x12" is louder than a 1x12", but how much depends on the cab design. I hear it as being around 2dB normally. But it also disperses better, so out to the side it may sound more, and directly in front may actually sound less (although still louder).

4x12"s are obviously louder again... with the same conditions. Hard to put an exact figure on it unless you measure it.

OK, that doesn't help much...

 

If you have 10" speakers that will handle that sort of power...!

... yes, that should give you a much bigger sound than the 1x12". I'm assuming the 4x10" is going to be closed-back though, or you still won't get a huge lot of bottom-end.

300W will be a lot louder than 80 - it's nearly four times the power, so you could expect an extra 5dB of headroom over the same 4x10" run from the 80W amp, and that itself will be louder than the 1x12" by a couple of dB probably.

You might want to use different speakers - you're obviously going to need two that will handle over 110W each, but the other two might sound better if they're closer to the power of the amp at 80W... eg two 50W speakers.

If you're going to build a cab like this, I would make it with an internal divider so that the 220W section is isolated from the 80W section as well - which will prevent any unwanted cancellations or distortion caused by the effects of the larger movement of the high-powered pair. You could then maybe even make the 80W section semi-open-back for better dispersion...

 

I guess we are done with the archtop for now

 

I would say that 80W into a 2x10" would be about the same volume as into the 1x12" - ie not as loud as 220W into the 1x12".

But in fact, if the 80W is tube-driven and the 220W is solid-state, you may be surprised how little perceived volume difference there is. Even if you don't think the tube amp is distorting - it might be, slightly; that's one of the reasons tube amps tend to sound louder, since the onset of distortion is soft. With a solid-state power section you know about it immediately, and it's not nice.

What speaker are you using just now? I'm assuming from the fact that you're putting 220W into it that it must be something like an EV, Peavey Black Widow or the like... which are also very efficient speakers. It's unlikely that you'll get two 10s which are any more efficient, even together.

I would definitely go for the 'complete' solution you already thought of. I might go even further than the previous idea of enclosing the two sets separately and enclose each of the high-powered pair in individual boxes too, if you're likely to want to run stereo effects. That will maximise efficiency and separation. You could also make the top section angled, if hearing yourself is an issue.

The advantage of running both amps into their own speakers is that you not only get more power, but you can 'tune' the tone you want using just the tube one, then make up any volume shortfall with the solid-state without affecting the sound.

 

I'd do it other way round - or you probably won't hear the 100W dry section.

I would make the top section an open-back (or semi-open) 100W, and the bottom as the closed/ported 220W.

This is going to be louder and with more headroom than 220W into the single EV 12", for sure.

220W into the two 10s will be about the same volume, probably - but you'll be adding another 80W tube-driven 2x10" on top of that.

 

That's exactly why I think you should put the 80W section in an open-back at the top. If it's in a closed-back near your feet, you won't hear much from it if there are two other speakers running at nearly four times the power above them.

But if the tube-driven speakers are in an open or semi-open cab at the top (closer to your ears, and especially if you make it an angled cab so they're pointing slightly upwards too) I think you'll hear them OK, especially as tube power amps have more presence than solid-state, so the volume difference may be less than you expect.

Solid-state is ideal for the extra bottom-end you want from the closed-back section though.