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Matttcattt 14th March 2004 09:10 PM

SPL and Watts
A while ago, I saw a table comparing SPL to Watts. I wonder if anyone could point me to one such as this. It showed the power (in watts) required to reach each SPL level.

Bill Fitzpatrick 14th March 2004 09:22 PM

A few seconds with Google finds this:

Sch3mat1c 14th March 2004 09:23 PM

Assuming you mean "SPL (dB, 1W/1m)", then there's no need: take the SPL figure and add or subtract as many decibels as compared to the 1W test figure. So if you put 10W through an 88dB/1W/1m rated speaker, you'll read 88 + 10*log(10W/1W) = 98dB. (In acoustical energy terms, this is 98 = 10*log(I/10^-12) ~= 6mW per square meter, in case you were wondering.)


till 14th March 2004 09:26 PM

1Watt into a speaker with 100% efficiency makes about 112dB SPL

a tabel efficiency - dB at 1W here

double the Watt get 3dB+

something here about dB

Matttcattt 14th March 2004 09:36 PM


Originally posted by till
double the Watt get 3dB+
I was thinking along the lines of a table with the watts starting at 1 and doubling, and the appropriate dB.

PS: Thanks for the replies.

till 14th March 2004 09:40 PM


I was thinking along the lines of a table with the watts starting at 1 and doubling, and the appropriate dB.
you need to give a speakers efficiency for this. In case its 100% you make

1W 112dB
2W 115dB
4W 118dB

in case you have a real world speaker with < 100% efficiency you start with the value from the table behind the link.

for example my speakers with about 100dB/1W

1W 100dB
16W 112dB (with ZEN)
32W 115dB (with OPA549 AMP)
128W 121dB (150W ratet input speaker)
256W 124 dB (300W max input power speaker)

kelticwizard 14th March 2004 10:00 PM


How is this chart? It is from Richard Small. It has acoustic watts on the left, and the equivalent SPL on the right. It also tells you how much air must be moved in a sealed system to produce what SPL, (or acoustic watts) at which frequency.

There are two charts, one in normal and one in Metric measurements.

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