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(RBernst929) wrote in message ...
Hi everyone. If i have a small, square 11'x 11' listening room
am i doomed to have no bass? No matter whether i add a subwoofer
or two? Can i never get any better bass than 50hz?

This is a common and, to some, and intuitive conclusion. The
assumption is that if you can't fit a wavelength in it, the room
can't support that frequency.

Intuitive as it may seem, it's wrong.

I wrote an extensive article debunking this myth in a recent
AudioExpress issue. Rather than going into that level of detail,
let me summarize the principles and conclusions.

"Sound," as detected by the ear, is the pysiological response to
movement of the eardrum. For the eardrum to move in response to
acoustical stimuli requires a periodic chnage in the difference
in pressure on one side of the eardrum vs the other. This is
germaine to your question, because what is says is simply that you
need a change in pressure of a sufficient amplitude and within
certain frequency limits to hear the sound.

Now, we do not "hear" wavelengths, we hear pressure variations.
So, to perceive a sound, all we have to have is the pressure
variations in the air in the vicinity of our ears, variations,
again, of sufficient pressure and within a certain range of
frequencies in order to hear something.

SO, all the loudspeaker has to do is cause those pressure variations
to happen, That's it. It doesn't make ANY difference how big the
room is. In fact, consider the lowly headphone if the "intuitive"
conclusion was correct, it would be impossible for headphones to have
ANY information below a few thousand Hz, being that the size of the
"room" they are working into is only a couple of inches in its largest
dimension.

Another example of how it is possible for "bass" to exist in a very
small enclosure is the Bruel & Kjaer pistonphone calibrator, used for
calibratiing microphones. It has a chamber which is on the order of
3/4" in it's largest dimension, suggesting a lower limit, using your
rule of thumb, of about 9000 Hz. Yet it operates quite nicely at its
design frequency of 250 Hz and, in fact, can be slowed down to a few
Hz. Above the frequency where simply air leaks dominate (a fraction
of a Hz, the response of this "room" is essentially flat from about
5-10 Hz to about 800 kHz, where is stops working in pressure mode
and starts working in various resonant exitation modes.

And that's what's happening in your 11' x 11' room. About 50 Hz is
the frequency where HOW the room works changes. At and above 50 Hz,
it's operating in various resonant modes. Well above 50Hz, it's
essentially operating in a diffuse field mode. Below 50 Hz, it's
operatring in pressure mode, down to the frequency where the room
"leaks" (determined by the volume of the room and the size of the
leaks).

But, most assuredly, you can have bass at and well below 50 Hz in
such a room.