I spent some time taking voltage readings using OmniMic and track 18 I believe which is the 50hz continuous tone. Using my trusty old Fluke Mod#16 voltmeter i adjusted the volume until I reach 2.0v at the speaker terminal. 2v into 4ohms should give me my system/room sensitivity. Then I measured all 4 terminals and all read between 1.98v- 2.01v. All channels are performing to spec. The subs are about 10-11ft apart and are equidistance to the MLP. The subs are 10.2ft from the MLP. So at 4x1w@50hz I get 100db. In my case that corresponded to a master volume setting of -3db
Next. I was interested in a comparison of room gain, not so much as to how much I get with my current sub/room combo but in relation to my former room. As always there's some variables. In this case its only a small difference, that of the box design (duo opposed vs single plane). The duo box was 8 cubes and the new box is 6.8. First room was 2700+ and my current room is 1700+. Everything else is exactly the same. From the drivers and amps to the frontend (Onkyo 885/Oppo 93/Omnimic CD track 2), same interconnects and speaker cable, to the multiples of Audyssey tunes I took of the system. Both subs are still sealed. I went back and looked back at all the data from the previous room and the new room. I unfortunately never took distortion measurement which now would have been very useful. My process for finding MaxSPL of the given sub system is to play track 2 and raise volume until audio clipping or compression of the waveform is showing. Having spent hours and overlaying hundreds of different graphs I've come up with this. This is the difference between the same sub system in a 1700cuft vs 2700cuft room.
Disregard the black wave. The red wave=1700 room and blue=2700 room. Interesting how the 1700 dominates at 15hz and 5hz but their equal at 10hz. Now to really analyze the difference I concentrated on the 20-50hz area. This is what I got.
Now I know the readings can be influenced by other sources. Even with the AC, washer and dryer on, noise in the room has never exceeded 60dbs. Despite that, I always make sure everything is off and take readings at a minimum of 95dbs, just to be sure. Comparing this graph I get a 5-9 db gain from the 1700 room compared to the 2700 room. So just doing a straight average I'm going to say a person can expect somewhere around a 6db difference between a 1700 vs 2700 cuft room. In other words you need to double the drivers or quadruple the power. I have 4x15 with 4x300w in the 1700 room. I would need 8x15 and 8x300w in the 2700 to match. Or 4x15(Ultras or XXX's needed) and 4x1200w.
Crunching numbers I came up with a 1700 cuft room is .63 of a 2700 cuft room. Or a 2700 cuft room is 1.59x a 1700 cuft room. Using this formula a 1700cuft needs 4 drivers. A 2700=8. A 4300=16. How about a 6800 cuft room. 32 drivers. Are you freakin kidding me. Suddenly those Maniacal Bass Mongers here don't seem so crazy. I don't have any proof to back up these numbers on the larger rooms or if it would stay linear like that as room size grows. But it sure opened my eyes as to how fast things can get out of control with rising room volume. Total cost of my modest system with 2 old amps and complete build is about $1700. You triple the room volume and you could very easily need to spend 10x that to match the performance. i just figured this was the new cold war. I had no idea of the necessity of the huge systems built here. WOW.