sub woofer sensitivity?

Question

What does the Sub-woofer sensitivity mean and what is it for?

Answer 1

Subwoofer's sensitivity is a number that state the efficiency of a subwoofer. Usually it's stated in ....dB/1W/1m.
It means, the subwoofer, if driven with 1 Watt of power, measured at 1 meter in front of the speaker, will produce a certain deciBell (SPL) of sound.
The bigger the number, the more efficient your subwoofer will be, meaning that it will sound loud with only small power amplifier.
For example, a subwoofer that has 90dB/1W/1m will produce :
90dB with 1 Watt of power,
93dB with 2 Watts,
96dB with 4W,
and so on each doubling of power will give you 3dB more SPL.
This mean that if that sub (A) is compared with the other sub (B)with lower sensitivity, let's say 84dB, it will be 6dB louder with the same power. Or sub (A) will only need 100W amplifier to achieve the same loudness that sub (B) achieve with 400W amplifier.
The caveat is, usually the high efficiency subs won't go as low as the big low efficiency ones, the choice is yours.
Hope this helps.

Answer 2

it is usually the signal to noise ratio,the higher the s/n ratio is the more efficient the subwoofer is so if you have a sub that has s/n of 90 db and a sub that is 95 db the 95 db will be louder with the same amount of power pushing it