Speaker sensitivity, volume, and orientation in a 2x12+1×15 cab?

[Hiwatts-n-Gibsons]

After the beginning of the year I am going to put together a Moon Cabinets 2×12" + 1×15" cab.

I know the 15" is gonna be on the bottom, and two 12"s on top. The 15" is a 103 db EV SRO15 rated at 8 ohms.

For the top two speakers I am thinking I need two 12" speakers right around 100 db each to match the volume of the 103 db EV in the cab. I know I need either two 16 ohm or two 4 ohm speakers to match the EV's ohm rating.

Is that correct, or can I go a little lower in efficiency if the two 12" speakers are on top? It's a straight front cab, so the top speakers will not be pointed upwards.

Also any recommendations for speakers in that range you might have paired with a 15" speaker would be cool if you have them.

 

[Hiwatts-n-Gibsons]

I am kinda leaning towards WGS Blackbird HP alnicos, Celestion Cream alnicos, 75hz Creambacks, or these bad boys here.

 

[Any Name You Wish]

Are you going to drive this hairy beast with a 100w tube amp? Your out of my league with this thing, but something tells me by mixing a 15" with two 12"s stuff is going to happen, and it may not be good stuff. Perhaps there is a reason most cabs are 4x10 or 4x12. I'm curious to hear what other more knowledgeable cab builders have to say.

 

[Hiwatts-n-Gibsons]

Are you going to drive this hairy beast with a 100w tube amp? Your out of my league with this thing, but something tells me by mixing a 15" with two 12"s stuff is going to happen, and it may not be good stuff. Perhaps there is a reason most cabs are 4x10 or 4x12. I'm curious to hear what other more knowledgeable cab builders have to say.

I've got some experience. I've had two SRO15 loaded 1x15's from Mojotone with convertible backs, and still have one. I just bought a second SRO15 for the cab I plan to order.

I've used them either, alone, together both open and closed back, or paired with an open back 2x12, closed back 1x12, and various 4x12's. It always sounded killer. Open back 15" cabs are truly next level amazing for sweet vintage clean tones, even more so paired with a couple good vintage 12's.

Best vintage '60s-'70s rock tone I ever had was a P90 loaded guitar or my Firebird into my Hiwatt with two Pulsonic cone Fanes in my openback 2x12", and the SRO15 loaded cab.

 

[Any Name You Wish]

I've got some experience. I've had two SRO15 loaded 1x15's from Mojotone with convertible backs, and still have one. I just bought a second SRO15 for the cab I plan to order.

I've used them either, alone, together both open and closed back, or paired with an open back 2x12, closed back 1x12, and various 4x12's. It always sounded killer. Open back 15" cabs are truly next level amazing for sweet vintage clean tones, even more so paired with a couple good vintage 12's.

Best vintage '60s-'70s rock tone I ever had was a P90 loaded guitar or my Firebird into my Hiwatt with two Pulsonic cone Fanes in my openback 2x12", and the SRO15 loaded cab.

Interesting. I never would have thought of that. Heck, I'm a 4x10 guy, what the hell do I know What amp head are you going to use?

 

[Hiwatts-n-Gibsons]

Interesting. I never would have thought of that. Heck, I'm a 4x10 guy, what the hell do I know What amp head are you going to use?

Whichever amp I choose at the time. I am particulay fond of the Ampeg with its super deep reverb through the open back 15", but all my amps have been played through them at one point or another. My Hiwatt and Reeves through a closed back 1x15 + 4x12 sounded amazing anywhere from clean to Electric Wizard to low tuned death metal with fuzz or distortion.

Funnily enough the 1x15 cab will probably spend much of its time paired with a Carvin X1 preamp pedal's 1 watt speaker out powering it.

The 1x15+2×12 cab will be for my big amps.

 

[PaulD]

There is a handy sound pressure level calculator here http://myhometheater.homestead.com/splcalculator.html

Using this suggests that 2 X 100 dB speakers will give the same SPL as 1 x 103 dB speaker so it looks like your calculations are sound but as you say positioning and listening distance will likely have an effect. The online calculator lets you enter different listening distances so might help to get an idea of what the effect might be.