Infinity Kappa 100.9w - Page 4

KAP PA
®
4
VENTED ENCLOSURES
A vented enclosure acts like a sealed
enclosure at frequencies above its tuned
(resonance) frequency.At resonance (which
is defined by the vent), the vent produces
the majority of sound – the subwoofer cone
is nearly stationary while the air inside
the vent vibrates.This provides greater
mechanical power handling at and above
resonance, but reduced mechanical power
handling below resonance. Since the
subwoofer cone and voice coil don’t move
much at resonance, airflow across the
voice coil is minimized and thermal power
handling is reduced slightly at resonance.
Vented enclosures provide better efficiency
in the 40Hz – 60Hz range, at the expense of
sound output in the lowest octave (below
40Hz).The use of an infrasonic filter is
recommended with vented enclosures.
An optimum vented enclosure for a Kappa
Series subwoofer is larger than an optimum
sealed enclosure.
See accompanying data sheet for specific
enclosure dimension requirements.
VENTED-ENCLOSURE PERFORMANCE ADVANTAGES
• An optimum vented enclosure has greater
efficiency and higher output in the
40Hz – 60Hz range than an optimum
sealed enclosure.
• An optimum vented enclosure provides
a greater sensation of bass than an
optimum sealed enclosure.
• A 100.9w or 120.9w subwoofer in an
optimum vented enclosure will require
less amplifier power to achieve a given
acoustic output (down to the enclosure’s
resonance frequency) than in an optimum
sealed enclosure.
VENTED-ENCLOSURE PERFORMANCE TRADE-OFFS
• Reduced output in the lowest octave
(below 40Hz).
• Reduced mechanical power handling
below the enclosure’s resonance
frequency.The use of an electronic
infrasonic filter is strongly recommended,
to reduce the chance of overdriving
the subwoofer below the enclosure’s
resonance frequency.
• An optimum vented enclosure will
always be larger than an optimum
sealed enclosure.
VENTED-ENCLOSURE CONSTRUCTION
Vented-enclosure construction is more
difficult than the construction of a sealed
enclosure.The enclosure volume and port
dimensions have a specific relationship
with the physical and electromechanical
characteristics of the subwoofer, requiring
that the recommended enclosure volume
and port characteristics be strictly
observed.As with sealed enclosures, use
medium-density fiberboard (MDF), glue
and screws to construct the enclosure,
and seal all joints with silicone caulk.
THE INFINITY RECOMMENDATION
100.9w and 120.9w subwoofers in
vented enclosures are recommended
for enthusiasts who prefer accentuated
bass response, for those who have plenty
of cargo space to devote to a subwoofer
enclosure and for those who will use a less
powerful amplifier to drive their subwoofer.
The volume and port dimensions indicated
on the included technical data sheet must
be followed precisely to ensure optimum
performance.