PSB Speakers PSB SubSeries 500 Guide D'utilisation page 8

few inches is sometimes enough to cure—or create—an intolerable
sound. The only way to find out what works best is by experimentation.
With full-range speakers, the range of places you can put the speakers
and still get proper imaging may be fairly limited, and some of these
positions may result in standing waves that can't be tamed. Things are
more controllable through the use of a subwoofer or two. Positioning of
the bass speakers has almost no impact on imaging, so a subwoofer
can be located with only standing waves in mind
Subwoofer Placement
There is no argument among audiophiles that the loudest bass output
from a subwoofer comes from corner placement. The natural
megaphone-like flaring outward of walls from a room corner focuses low
frequencies—giving them no place to go but toward you. In the case of
subwoofers, there is no automatic penalty in giving overall balance for
this maximal bass, since your main speakers can be located elsewhere.
It still may be too much bass for your room or (more particularly) your
favorite listening spot in the room, but unless you are seated in a "null"
spot, where sound from the sub is cancelled or diminished by out-of-
phase reflections from elsewhere, there should be plenty of bass from
corner placement.
If you are seated in such a null spot, your only real choices are
generally to move either the subwoofer or your listening position until
bass returns to the point that satisfies. Cranking up the level control or
changing the crossover point almost certainly won't help much. But
flipping the phase control 180 degrees sometimes may make a
difference, especially if the null is a product of cancellations caused by
interaction with low frequencies from your main speakers.
If you are in the opposite sort of situation, where direct and reflected
bass waves converge in phase and produce a strong peak at your
listening location, you can—if you like—deal with that both with changes
in placement or in the position of your sub's level control (or, less likely
but possible, the crossover frequency chosen). We say "if you like"
because there is no such thing as too much bass for some listeners,
and we don't want to be dogmatic. You are definitely the one who has to
be pleased, unless your Significant Other chimes in to the contrary.
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