Hertz Meter Reading Device

As the frequency gets lower, you'll notice the volume decreasing as well. There will be a point where the tone is no longer audible. You have just experienced the bass roll off of your system.

As well as the roll-off of your ears, of course, Bob, which may very well be more significant than the system roll-off which you are trying to determine, unless the tones are played at extremely loud volumes. Remember the Fletcher-Munson effect.

Regards,
-- Al

My gripe about frequency response specs is that they ought to be measured not only relative to the SPL level at 1000 Hz, but also AT some particular SPL level at 1000 Hz. If the SPL is very low the woofer will not run out of excursion and the LF performance will be better, but unfortunately you won't be able to hear it :-(

Response to 11 hz does NOT mean you have useful bass (not base) to 11 Hz. That number is probably down by 20 dB, practically inaudible relative to higher frequencies. Are there recordings that go below 20 Hz?

Most subwoofers start rolling off at 30 Hz or higher with a 24 dB per octave slope. By the time they get to 25 they could be down by 6 dB or more. They may also produce gross amounts of 2nd harmonic distortion. Taking the Fletcher-Munson hearing curve into account, we'll hear the harmonic more than the fundamental.

There may exist frequency meters, but as stated above, all you need is a test CD, an SPL meter, AND the response curve of the meter to correct your readings.

You'll have to place the mic or meter right up to the sub's cone(sealed) or port. Otherwise you'll only be measuring how the sub interacts with your room.