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Understanding Power Requirements
#198667 03/02/08 06:30 AM
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fredk Offline OP
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Just found a web page that explains some of the stuff I have been wondering about with respect to power requirements for speakers. I was wondering what sort of head room requirements I might have depending on the dynamics of the music I am listeneing to, the volumes and listening distances.

The page even has a link to a calculator you can use to figure out what you need for your particular situation. Its meant for professional musicians, but it should work just fine for the rest of us as well.

I found their suggestions for headroom for different types of music (as much as +25db for some types of music) quite interesting.

Crown audio link

Enjoy.

P.S. I know, I know, M60s are easy to drive. Any decent receiver will do. I'm bored...


Fred

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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!
Re: Understanding Power Requirements
fredk #198668 03/02/08 06:55 AM
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fredk Offline OP
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OOooooh, this is fun!

M60 at 2.5 meters, 95 db spl and 10db headroom = 99w
Bump that to 105 db spl and the max power required jumps up to 313w!

So, if you listen to music with a lot of dynamic range, your power requirements really jump.

Want to handle 25db peaks withoug clipping at 95db spl? You will need a cool 3,132 amps of power!

Fred


Fred

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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!
Re: Understanding Power Requirements
fredk #198676 03/02/08 04:20 PM
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...and a hearing aid.


M80s/VP160/QS8s/EP350; M22s; M3s.
Re: Understanding Power Requirements
doormat #198713 03/02/08 09:26 PM
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fredk Offline OP
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Meh... need a hearing aid already... ;\)

For me, playing with the calculator really drove home what folks here have been saying. I guess I am a visual guy, because I couldn't quite put it all together before playing with the calculator.

One thing I still wonder about is what the danamic range I can expect out of the music I listen to. The Crown website seems to suggest +15db peaks is reasonable

Something Alan Loft wrote in his article about power has stuck in my mind. Music played cleanly as high spls dosn't sound loud.

Put that together with a speaker like the M80 or less efficient speakers in a larger space with music that has high dynamic range, and I can see how you very quickly exceed the power requirements of your average receiver if you want clean playback at reasonable volumes.

As for hearing loss, I wonder if very short peaks 25db above and average listening volume of 85db will lead to hearing loss. Thats a lot different than running equipment for 8 hours a day that generates a continuous 110db of noise.

Fred


Fred

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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!
Re: Understanding Power Requirements
fredk #198729 03/02/08 11:55 PM
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Good article. I like the quick way the calculator adjusts for sensitivity and dyanmic range.


John
Re: Understanding Power Requirements
jakeman #198746 03/03/08 12:34 AM
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Holsts' The Planets has about 50 db range so to listen at a mere 60db @ 2.5 meters, for the quiet parts the Amp requirements jump to 198W and that's if I use the in room sensitivity of the M80s. When using the anechoic I need - 496W


Jason
M80 v2
VP160 v3
QS8 v2
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Samsung 85" Q70
Re: Understanding Power Requirements
jakewash #198754 03/03/08 12:45 AM
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I think this speaks to have distributive power :)Not all your channels need to have this at the same time. I would use 25db as a realistic expectance..

Last edited by mapatton; 03/03/08 12:47 AM.

Mark
Pio 94,SB3,BD30,A35,Pio 48AV.Pronto 7000 controlling all. Getting ready for 22s, 150 & QS8s.
Re: Understanding Power Requirements
mapatton #198759 03/03/08 12:50 AM
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When listening to the Planets, SPL meter in hand, the range peaks at 53 db. so 25 would not suffice, as we are talking total range.


Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70
Re: Understanding Power Requirements
jakewash #198768 03/03/08 01:46 AM
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So plan on 50+? Will do.

Gosh like I needed another reason to get a new amp.


Mark
Pio 94,SB3,BD30,A35,Pio 48AV.Pronto 7000 controlling all. Getting ready for 22s, 150 & QS8s.
Re: Understanding Power Requirements
jakewash #198769 03/03/08 01:47 AM
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fredk Offline OP
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John. I agree: pretty cool!! I think these two pages should be stickied on one of the forums here. Its a very concise explanation of power requirements and the things that AND it gives examples of spl's and headroom for various types of music.

Mark. It took a while to parse that first sentence, but I get you. I don't think a lot of people appreciate just what Axiom has done with their new amp.

If +25db is a reasonable requirement for peaks, at 85db spl, I would need 200 amps to drive the M60s clean... but I can get to about +23db on 120w On the Crown page they use +15db peaks as typical for home audio. For +25db I would need around 200w.

So, how much power I need really, really depends on how loud I like to listen to my music. This is something I want to establish when I go to give various speakers a listen at Axiom.

 Quote:
so 25 would not suffice, as we are talking total rang

This is where I get confused when people talk about dynamic range. Are youl talking about total range as in from the quietest to the loudest? If I understand the way the calculator works, they are talking about peaks above average spl.

Another interesting thing on the link is that their chief engineer says that amplifyer continuous and peak power are virtually identical. Maybe he was refering only to Crown's amps, but I don't think so.

Fred


Fred

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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!
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