I'm trying to decide between a home theater system powered by either an Axiom M80 centered system, or Brand X. I say Brand X because I've done the research, and I know what to expect if I mention a specific name. I'm not here for that. I'm here because I have a power question.
My theater room will be probably about 2000 cubic feet, give or take, and sealed. The room will be well treated with acoustic treatments placed from a home theater perspective. (dead front wall, broadband absorption along the sides up to ear level, rear treatments, bass traps) So for the purposes of this query, I will probably be most interested in the Anechoic sensitivity rating. (don't worry, I'll be trying to keep the RT60 within a reasonable range)
Okay, with the background info taken care of, here is my question. How much power do I need to run an M80 system at reference levels? Reference being defined, as I understand, by 105db peaks at the listening position from each speaker. (115db from the sub. I'll have two SVS PB13Us on task for this)
I believe I have come up with the correct answer, but want to have my numbers checked.
Given the lowest sensitivity of 91db anechoic, and a seating distance of 3 meters, the
Crown Audio Amplification Calculatgor tells me I need 451W of power to achieve 105db, and have 3db of headroom left over.
Based on this calculation, I have come up with two possible amplification options for an M80 system:
Axiom Audio Reference System 1
M80 Twoers at 91db @ 1w/1m
VP180 Center at 91db @ 1w/1m
QS8 Surrounds at 94db @ 1w/1m (2 pairs)
Yamaha RX-V765 Reciever (pre-outs going to external amps listed below)
Emotiva PMA-7350 350WPC 7 channel amp $3000
So, bearing in mind that I need 451W to play reference, and have headroom, the M80 and VP180 are both 4 ohm speakers, and the PMA-7350 is capable of 4 ohms. So, given that 4 ohm wattage is usually higher, the Emotiva should be able to give me 105db and still have some leftover headroom.
Will this provide reference listening levels without clipping?
Axiom Audio Reference System 2
M80 Twoers at 91db @ 1w/1m $1628/pr
VP180 Center at 91db @ 1w/1m $850
QS8 Surrounds at 94db @ 1w/1m $1316 (2 pairs)
Yamaha RX-V765 Reciever (pre-outs going to external amps listed below)
Emotiva XPA-2 300W @ 8, 500W @ 4 $799
Emotiva XPA-5 200W @ 8, 300W @ 4 $899
This is $1300 cheaper, but at the cost of headroom. The XPA-2 should have the headroom to drive the M80s at 4 ohms. But the XPA-5 could be an issue. The center will call for 226 watts of power at 4 ohms to achieve 105db. The XPA-5 is rated for 200W @ 8, 300W @ 4 ohms. That's only 1db of headroom for the center. The surrounds are 8 ohms, and will call for 113W to drive them at 105db. That leaves 2.5db of headroom.
So, will this system also be enough, or is it too borderline? Which of these setups would be the most balanced and cost efficient, without compromising the ability to play at reference volumes with no distortion?
Thank you!
