2
THREE's amplifier's response is contoured to restore
the low frequencies to the proper level induced by the
crossover. The SUB THREE's input Impedance is high
enough (over 100k ohms) that it has no discernible effect
on the main amplifier's output.
THE SUB THREE CROSSOVERS
Each SUB THREE subwoofer needs an M5-HP
crossover.
Mono OR Stereo Bass?
There are significant advantages to using two sub-
woofers. Summing the channels into a single subwoofer
reduces or cancels all the low-frequency information
containing phase differences between the channels.
Stereo subwoofers reproduce all of the bass information,
complete with the phase differences that help provide the
imaging and location clues we use to place people and
things at distinct points in the sound field. Stereo
subwoofers also lend themselves to natural placement
near the corners where the low-frequency room gain is
more linear and often desirable.
ADJUSTABLE SENSITIVITY, ROOM EQ, AND Q
FEATURES EXPLAINED
The sensitivity, room EQ, and Q controls on the
SUB THREE's input plate allow you to match the bass
level to the full-range speakers and tailor the
characteristics of the low frequencies.
The sensitivity control's label is in dB to initially
match to the main speaker's efficiency rating, the Q
control starting setting is "1", and 11-bands of EQ at
noon.
The Q control can then tailor the SUB THREE's low-
frequency response to compensate for room
characteristics and to best suit your sonic tastes. The Q
control is from 1 to10. Position 1 provides the tightest
bass and best transient response, while position 10
emulates a typical home theater subwoofer's peaked
response. The Q control effect on the SUB THREE's
frequency response is illustrated in the graph below. For
clarity, only positions 1, 5, 7, 9, and 10 are shown. (The
chart does not include the effects of low-frequency room
gain.)
When you want more of a
conventional home theater sound,
turning up the system's bass tone
control will provide the extra low-
frequency emphasis that is
desirable in many movies. If your
system does not have tone controls,
setting the SUB THREE's Q control
to a higher number will yield similar
results.
The 11 Band EQ adjusts your
SUB THREE precisely to the room
bass nodes to the sub's position.
Setup is explained in a later
section.
Superimpose the response of the
subwoofer over the response of the main
speakers and the crossover point is
evident.
Response
of
the
main
amplifier
and
speakers
with
the
crossover
induced
low-freqency
roll-off.
This
is
also
the
input
of
the
Sub
amplifier.
Output
of
the
SUB
THREE
amplifier.
The
contour
is
the
oppisite
of
the
low
frequency
roll-off
induced
Response
of
the
SUB
THREE
subwoofer.
The
coutour
in
the
amplifier
boosts
the
frequencies
below
the
crossover
pointback
to
flat
and
rolls
off
the
subwoofer
above
the
crossover
point
These
examples
show
the
interaction
between
the
crossover,
the
SUB
THREE
amplifer,
the
SUB
THREE
subwoofer
and
how
they
work
together
to
provide
accurate
and
extended
bass
response
with
your
main
speakers.
