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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.