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Do you remember how the power to db ratio goes?

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Joey_V

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I forgot how they went...

Was it if your speaker is 90db efficient, this would mean at 1 watt, you get 90db out of the speaker from 1m?

Now, what happens when you start moving up the SPL ladder? What happens to the power draw (watt)?

Was it every 3db requires double the power?

Just wanted to brush up on my facts... I have Stesom's Rotel RB1090 behemoth coming to my listening area in a few days.

Joey :)
 
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jleblanc77

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Joey_V said:
I forgot how they went...

Was it if your speaker is 90db efficient, this would mean at 1 watt, you get 90db out of the speaker from 1m?

Now, what happens when you start moving up the SPL ladder? What happens to the power draw (watt)?

Was it every 3db requires double the power?

Just wanted to brush up on my facts... I have Stesom's Rotel RB1090 behemoth coming to my listening area in a few days.

Joey :)
Every additional 3dB that the speaker produces means it is putting out twice the power, and would typically take twice the input power to do that. That's true up until the very high end of the scale, when the speaker doesn't necessarily work @ 100% efficiency, and it could take more than twice the power to double the output.

Also, don't forget that it takes 10dB to actually double the perceived volume level.
 

Audiophiliac

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He is correct. 10dB = doubling of perceived sound pressure level (volume) It also requires 10x the power.

3dB = normally used as the lowest most humans can detect a noticeable difference in volume (some can hear less, some takes more). Every 3dB of increase in volume requires a doubling of power.

I dont know if the way you figure it is how it actually works. If a speaker it measured 90dB 1w/1m probably at 1kHz, if you double the power, you may or may not get 93dB 1w/1m at 1kHz. Its not uniform across the frequency range either. You have impedance curves to deal with, and other electrical and mechanical forces to deal with. :)
 
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Tiberium

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Also, don't forget that it takes 10dB to actually double the perceived volume level.
I thought a 3db increase was twice as loud but I will have to do some research and come back with a link.
 

amey01

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The scale is logarathmic. A pair of 87dB speakers will produce 87dB (A) of sound at a distance of 1m for an input of 1w. An increase of 3dB represents a doubling of the power, but a tiny increase in sound from a human's point of view. To double the perceived loudness represents a 10dB increase in decibels.

So, if we drive our 87dB speakers with a 100w amplifier and we want to double the loudness of this system we will need to do either of the following:

Get a pair of speakers rated at 97dB efficency
OR
Upgrade to a 1000w (1Kw) amplifier

Alternatively, if we double the amplifier power to a 200w model we will achieve a mere 3dB increase in loudness which would barely be noticable.

I think thats how it works! Of course, none of this has any impact on sound quality, which is what all of us (hopefully) are interested in - most of us have heard 3w SETs produce stunning results!
 

Spike

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While we're talking about power and loudness, here's a convenient utility for calculating the db level at your listening position: Peak SPL Calculator. Hmm, maybe I should post this link in the tweak section for easier access :) Hey Rod, does this qualify as a...tweak?

Spike
 

amey01

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Spike said:
While we're talking about power and loudness, here's a convenient utility for calculating the db level at your listening position: Peak SPL Calculator. Hmm, maybe I should post this link in the tweak section for easier access :) Hey Rod, does this qualify as a...tweak?

Spike
Cool little tool.....I wonder how accurate it is though - especially given the dispersion characteristics of electrostatics?
 
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