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#338759 - 02/16/11 05:01 PM How much power is needed to play M80s at reference
DanLW Offline
frequent flier

Registered: 07/30/10
Posts: 11
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!


Edited by DanLW (02/16/11 05:17 PM)
Edit Reason: Fixed links

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#338763 - 02/16/11 05:31 PM Re: How much power is needed to play M80s at reference [Re: DanLW]
Ken.C Offline
shareholder in the making

Registered: 05/03/03
Posts: 17809
Loc: NoVA
I'm not certain about your figures (I'll leave that to Chris), but I would advise looking somewhere in addition to Emotiva. Budget amps (for lack of a better word) are just that--budget. If you're looking to push that much power, I'd be looking at Outlaw (maybe), Parasound (definitely), Rotel, ATI, Bryston, that sort of thing.
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I am the Doctor, and THIS... is my SPOON!

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#338764 - 02/16/11 05:40 PM Re: How much power is needed to play M80s at reference [Re: Ken.C]
Adrian Offline
axiomite

Registered: 12/27/08
Posts: 6622
Loc: It's all about the location.
Jeebers! that kind of power in a 2000cf room is going to be loud!

Some of the pro-amps are connect friendly for HT use, if you don't mind occasional fan noise on quieter passages(unless you swap it out for a quieter fan). Of course, at those kind of levels you wouldn't be concerned about noisy fans.
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Half of communication is listening. You can't listen with your mouth.

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#338765 - 02/16/11 05:41 PM Re: How much power is needed to play M80s at reference [Re: DanLW]
BlueJays1 Offline
connoisseur

Registered: 09/19/08
Posts: 4082
Loc: Porch,enjoying Bombay Sapphire
You sound like a candidate for horns or some type of pro speakers as it seems high sensitivity and efficiency seems to be your main concern. That said most won't have the fidelity of the Axiom system. I would suggest buying as much power as you can afford. Maybe even look into some pro amps. The M80's are really geared for very high power handling. The limit will be the amp feeding it.
_________________________
I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne

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#338766 - 02/16/11 05:44 PM Re: How much power is needed to play M80s at reference [Re: BlueJays1]
Ken.C Offline
shareholder in the making

Registered: 05/03/03
Posts: 17809
Loc: NoVA
I've heard M80s playing at >105dB sustained. They can handle it just fine. The dude was powering 5 of them (!) and 2 QS8s with 4 Parasound Halo 500 WPC 2 channel amps.
_________________________
I am the Doctor, and THIS... is my SPOON!

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#338769 - 02/16/11 06:00 PM Re: How much power is needed to play M80s at reference [Re: Ken.C]
Wid Offline
axiomite

Registered: 06/22/03
Posts: 6722
Loc: The Peoples Republic of Il.

I have reached 105DB continuous in my 20x13 room with a Rotel RB1080. I like it loud but that is to loud for me. The amp could handle it well, the M80s handled it just fine but my ears didn't do so well.
_________________________
Rick


"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud


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#338770 - 02/16/11 06:14 PM Re: How much power is needed to play M80s at reference [Re: DanLW]
ChrisC Offline
newbie

Registered: 10/05/10
Posts: 2
Emotiva has decided not to release the Emotiva PMA-7350 350WPC 7 channel amp $3000. I think you will have to select alternate power.

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#338773 - 02/16/11 07:17 PM Re: How much power is needed to play M80s at reference [Re: ChrisC]
ClubNeon Offline
connoisseur

Registered: 02/06/09
Posts: 3452
Loc: Western Maryland, USA
It's going to be hard to find a 450 Watt @4 Ohm amp, that isn't really expensive. The price is slightly justified too, because 200 Watts isn't too hard to do, maybe 300 into 4 Ohms, but once you start nearing 500 Watts the design work that goes into amps of that caliber has a cost.
_________________________
Pioneer VSX-1018AH-K, PDP-5020FD, DV-79AVi
Axiom M22s, VP150, QS8s
Sony PS3, surround backs
-Chris

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#338775 - 02/16/11 07:31 PM Re: How much power is needed to play M80s at reference [Re: ClubNeon]
BlueJays1 Offline
connoisseur

Registered: 09/19/08
Posts: 4082
Loc: Porch,enjoying Bombay Sapphire
The Behringer EP2500 will do that into 4 ohms and then some. It will also provide about 1000 watts into 2 ohms (verified by 3rd party testing). These would be the most cost effective solution and offer better performance than the Emotiva but you would also have fan noise to deal with which will be an issue if you do any low level listening smile or have to mod the fan on the unit(s).

Behringer can be hit or miss and quality issues can be a problem with their products just so you know.
_________________________
I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne

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#338776 - 02/16/11 07:38 PM Re: How much power is needed to play M80s at reference [Re: BlueJays1]
ClubNeon Offline
connoisseur

Registered: 02/06/09
Posts: 3452
Loc: Western Maryland, USA
The fact that Behringer has quality issues backs up what I'm saying. It's not cheap to build a rock solid 500 Watt amp.

The ButtKicker LFE amp does 1000 Watts into 4 Ohms, and 2000 Watts into 2 Ohms. But you don't want to listen to it through a speaker.
_________________________
Pioneer VSX-1018AH-K, PDP-5020FD, DV-79AVi
Axiom M22s, VP150, QS8s
Sony PS3, surround backs
-Chris

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