Home Speaker Asylum

General speaker questions for audio and home theater.

Adding a third or fourth subwoofer may improve bass at your seat in your room ... or maybe make it worse!

That's my point.

You could buy an extra subwoofer or two ... and hear no improvement, or hear a deteriorated bass frequency response ... meaning your money should have been used for upgrading the front speakers ... or upgrading some other components ... or given to your favorite charity.

Measuring bass by using frequency response standard deviations is not going to tell you whether the bass frequency response at YOUR SEAT sounds good.

It only takes one bass peak to ruin the reproduction of one bass guitar note or one bass drum strike -- the rest of the bass frequency response could be ruler flat causing a pretty good standard deviation measurement ... but the bassline won't sound right (and could sound horrible if the bass drum excites that one bass peak)!

Tom Nousaine found that fully exciting every room mode with a corner subwoofer is usually a good thing for bass if the resulting bass peaks are well distributed ... because our ear's one-third smoothing ability can work well on well-distributed bass peaks.

If you had three bass peaks under 80Hz. from standing waves (typical room) and could eliminate two of them, you might think the bass would sound better.

In reality, the one remaining bass peak is likely to be more audible and more annoying than it was before, possibly making the overall subjective bass quality worse than it was with three bass peaks.

The most serious bass problem in small rooms is insufficient modal density under 100Hz.

There are not enough bass peaks and nulls under 100Hz. for our ear's one-third octave smoothing ability to smooth out.

Above 200-300Hz there are so many standing wave and 1/4 wavelength cancellation peaks and nulls that they can be blended together by our one-third octave smoothing ability and we can't hear them.

Most common among people who try more than two subwoofers is placing ALL the subwoofers on the ground where they will ALL excite the very important first-order axial floor-to-ceiling standing wave (71Hz, boom with a 8 foot ceiling ... 56.5Hz. boom with a 10 foot ceiling).

Tom Nousaine found this to be the main reason five "surround" subwoofers did not outperform one subwoofer in a corner (other than having higher maximum SPL).

All the five "surround" subwoofers were located on the floor and caused a huge boom at 71Hz. -- the last thing you want when trying to reproduce a bassline just as the bass musician played it.
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Richard BassNut Greene
Subjective Audiophile 2007


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