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Subwoofer Direct switch- In/Out
This switch allows the electronic crossover circuitry to be removed from the signal path.
This is required in certain installations which route the signal through external processors
with a crossover circuit of their own, such as the new digital units. Simply move the switch
to OUT to disengage the built in crossover. For all other installations which do not have
a separate electronic crossover we recommend you leave the internal crossover IN to
provide optimum performance.
Auto turn on switch- Auto/On
The auto turn on switch allows the user to utilize or bypass the automatic signal sensing
circuitry. When set in the AUTO mode with main power ON, the subwoofer will turn itself
on when an input signal is present. If no signal is present, after several minutes the unit will
shut itself off. When set in the ON mode, the auto turn on/off function is bypassed and the
unit will be on whenever the main power switch is on.
Power switch
The master power switch is located on the right half of the unit. This rocker style switch is
the main on/off for the unit. This switch should be set to position 1 (up) for on, and 0
(down) for off. If the unit is to be left unused for an extended period of time, the master
power switch should be turned off.
Line-level connection
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Figure 1 shows connection to a pre-amplifier's main outputs and returning them to your
amplifier inputs.
When installed in this fashion, your satellite speakers will be crossed over at 85Hz which
removes the lower bass from your amplifier and speakers, enabling them to do a better job
reproducing high frequencies. By utilizing this method, you will have a bi-amplified system,
gaining improved power and headroom for your system.
The first type of protection circuitry which prevents overdriving of the speaker or amplifier
operates constantly without being audible under most situations. In some extreme
situations (sustained high output levels), the unit may shut down momentarily. The green
power led may also blink rapidly. This indicates operation of the thermal protection
circuitry. If this should happen, you should reduce the volume setting or shut the unit off
until normal operating conditions return. You may also want to plug the unit into a different
wall outlet, as dropping power line voltage will be most noticeable under strenuous
conditions.
Distortion in loudspeakers
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Nonlinear distortion is a problem which plagues all speakers. This particular type of
distortion is a common problem in subwoofers, which must move large amounts of air to
produce adequate levels of deep bass. Nonlinear distortion is defined as any form of
distortion that moves energy from one portion of the audio frequency spectrum to
another. When a single tone is applied to a nonlinear system, the result is harmonic
distortion. In which some of the energy leaves the system at multiples of the original
frequency. When multiple tones are applied, intermodulation tones are produced, usually
as simple combinations of the input frequencies. Generally, 3% distortion is considered a
reasonable amount for speakers. This means that 3% of the total energy leaving the speaker
is at frequencies other than the intended input signal.
Most subwoofers on the market today however, produce much more than 3% distortion
at common listening levels. Many models we have tested produce greater than 20%
distortion @ 20Hz when driven to 100dB. This is a typical output level obtained in many
systems, particularly home theater systems. Even at 1 watt, many conventional units
produce several percent distortion. Secondly, the odd order, higher harmonics are much
more offensive to the human ear than the closer 2nd harmonic.
An interesting result of this reduced distortion is that some of the bass, when played over
an extremely accurate subwoofer system, seems to actually be missing. The truth, however,
is that the "missing" bass was never there to begin with! Distortion products of conventional
continued. . .
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