Decibels [Archive] - Audio & Video Forums


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11-19-2009, 08:56 PM
Hey guys, I was just thinking about something I heard quite some time ago. If you double your power output, you gain 10dB. For every speaker you add from the same amount of power, you gain 3 dB. So, if you add a second subwoofer the same as the first one you'll gain approx. 13 dB. 10 from doubling power and 3 from another speaker. Can anyone confirm if this is right?

Mr Peabody
11-19-2009, 09:05 PM
Decibels aren't as easy as the little quotes people repeat and it tends to start and argument because some hear the 3dB thing where others hear the 10dB thing. Here's a good link I keep for just such an occasion, a good explanation of dB's:

11-19-2009, 09:07 PM
The 10 dB concept is a theory on how much increase it takes to create the perception of double the loudness. Double power is +3 dB.

Two sources (in this case, subwoofers) that are the same loudness as each other will be 3 dB louder than only one of them, regardless of the proposed idea that there's now twice as much power.

11-19-2009, 09:50 PM
If you double your power output, you gain 10dB.

As 02audionoob said, if you double the power output, your gain will be only 3 dB.

This chart from Mr. Peabody's link explain it better.

11-20-2009, 06:25 AM
However, if you're looking to increase your bass output a lot of advantage can be had by placement. I believe I heard that for every room boundary you place your subwoofers next to, you gain 3db. A maximum of 9db gain by placing it in a corner. Of course that will depend on your listening position and whether you're sitting on a peak or in a trough.

11-26-2009, 08:00 PM
Standard amplifiers are voltage sources so If you parallel a second speaker you will double the current draw from the amplifier and thereby double the amplifier power output.

Thermodynamics says there is never a free lunch.