Originally Posted by LTD02
"Am I calculating incorrectly?"
Good doc, Your calculations are more or less right for 2 pi space aka standing outdoors in a field. In a room, the wall reflections increase sensitivity quite a bit. The amount of gain is both frequency, placement, and treatment dependent. You could easily pick up 3-6db vs. 2 pi space model in room in the mid-bass region. Also, the lower your noise floor, the higher the sound level will seem. I like 95-100 db while in my car on the highway, open windows, with a noise floor of 80db because my ears are adjusting to protect given how much ambient noise there is. At that level, I can't hardly hear myself while yelling, but the sound doesn't seem "too loud". In a dead quiet room, the same 95-100db sound out of the quiet, is painfully loud because the muscles in my ears have gone for max sensitivity. Our ears actually work much like our eyes. Walk into a room after being out in the snow and you won't be able to see because your eyes have adapted to protect them from too much light. After a while, they re-adjust. Our ears work much the same way.
GoodDoc, Scott is planning to use 4 2226J's per main. Those are 97db sensitive drivers. Four of them would be 103db at 1w. That is about about 105db at 12ft with 10w. Of course, he would have 3 of these for his L/C/R so it isn't absolutely necessary to have a full 105db from any one speaker, although that does meet spec.
10w was an exaggeration. Yes, 50w would be good. That would be good for at least 3db of headroom at 105db in a 20ft room by my rough calcs.
As far as chip amps are concerned, I was not referring to the Sonic Impact amp. The DTA-100 measures far better and does 30w at 8ohms with .05%THD. It might be barely under powered, but I doubt it given the highly efficient setup.
I'm not suggesting the chip in the DTA is the end-all, but if Scott has been sitting on his project for 2 years saving up for some 2000w/channel uber pro amps, he could certainly use this as a stop gap.
Thylantyr, how much headroom do you deem necessary, 20db?
Do all chip amps suck? How about the IRS2092, LME49810, and LM4702? Properly implemented, those are all very high quality chip amps, IMHO.