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Author Topic: Power to speaker number.  (Read 1890 times)

Roger Goldsbrough

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Power to speaker number.
« on: January 07, 2007, 02:25:28 pm »

Hey, I'm a bit confused..  Sad   If you do understand - I'd be grateful for a response.

From Dickason's cookbook -If you use one 10" driver at 50W in a specific room you get 97dB SPL. If, you then increase the amp power by 2 times, to 100W you get 100dB. OR double the number of speakers and keep the power at 50w and get 103dB. I quote "doubles the cone area and increases acoustic power by a factor of four. The one acoustic watt of the combined drivers could produce nearly 103dB in the same room driven by the original 50W of output power. To reach the same SPL level with a single driver would require 200W"

Uh, what? If this is a universal law, why don't we all have 500 10w speakers rather than 10 500w speakers? - We would get.. well, LOADS more acoustic power right? (we're talking some massive exponential numbers here.. no pen to hand Smile )

This seems to be a general statement in the book, but from this forum i get the impression the only possible real world application of this rule appears to be coupling -from placing two subs close to eachother and therefore increasing efficiency (less than 1/3 of a wavelength). If what he is talking about isn't simply a typo of somekind and is in fact coupling.. then thats fine.. I just need to know more about it.

Is that what he's talking about or is this something entirely different?

Thanks!

Rog

Ivan Beaver

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Re: Power to speaker number.
« Reply #1 on: January 07, 2007, 03:31:52 pm »

It depends on exactly what is meant by 2 drivers at 50watts.  Is that 50 watts per driver or 50 watts total-25 watt/driver?  If it is 25 watts/ driver  then there is a typo.

You will typically get 3 db for doubling the power and 3 dB for coupling drivers-HOWEVER there are lots of limitations on this so that you do not get the "free: 3db for more than the first couple of drivers- these include combfiltering, distance of drivers from measurement position, piston area vs freq etc.

As usual, there is not a simple one answer for the question.
Logged
For every complicated question-there is a simple- easy to understand WRONG answer.

Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

Roger Goldsbrough

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Re: Power to speaker number.
« Reply #2 on: January 08, 2007, 04:56:52 am »

Yeah, ok. Cheers.
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