efficency, spl @1W/1m :85.2db

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=76889
Printed Date: February 16, 2026 at 2:01 PM

Topic: efficency, spl @1W/1m :85.2db

Posted By: xtremej
Subject: efficency, spl @1W/1m :85.2db
Date Posted: April 27, 2006 at 12:14 PM

I am running into a wall trying to figure this out, is it 6:00 yet? Anybody have any ideas what this means. It is on a spec sheet for an concept xt-124 12" sub. I understand its a measure of efficency but can someone break it down for me?:errr:

Thanx a million

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Replies:

Posted By: SoundAudio
Date Posted: April 27, 2006 at 12:22 PM

It is the spl measured at 1 meter form the sub with it being powered by one watt. It can be calculated by:

n = 9.64x10^-10 x Fs^3 x Vas / Qes

That is the efficiency of the driver.

SPL = 112.2 + 10 x log (n)

This will give you the sensativity rating of the driver.

The efficiency of the driver tells you how efficiently the driver converts electrical power to acoustical power. If you take n x 100 to get it into a percent you will realize that is a low number around 1%. This looks poor but it is just how present drivers work.

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Good Luck!
-Thad

Posted By: DYohn
Date Posted: April 27, 2006 at 12:23 PM

It's not efficiency, it's sensitivity. It means the speaker was tested with 1 watt input measured 1 meter away and generated 85.2db or sound pressure. Generally this is at a fixed frequency like 1KHz.

I wrote up THIS description of sensitivity specs a while back. You might find it useful.

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Posted By: xtremej
Date Posted: April 27, 2006 at 12:41 PM

Whew I read it, now I need a nap. Ha Ha. I'll probably read it a few more times but it make sense, knida scarry.

Thanks

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