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Kappa Perfect VQ woofers are designed
to provide optimum system Q and
frequency response in infinite-baffle
applications or in very large enclosures
with no insert installed in the polepiece.
The smaller of the two inserts is
intended to be used with woofers
mounted in medium-sized sealed boxes
and vented boxes. The largest insert is
intended to provide optimum Q for very
small sealed or vented boxes or for use
with woofers used in SPL competition,
where the enclosure is designed to
provide the highest output possible
at a single frequency.
While it may seem that the most
forceful motor will provide the best
performance in all applications, in
reality that is not the case. When a
woofer is mounted in an enclosure, the
resonance of the woofer becomes the
resonance of the combination of the air
inside the box and the woofer, and Qts
(speaker Q) becomes Qtc (system Q).
For example, Figure 4 shows the
response of a Kappa Perfect VQ
subwoofer in a sealed box optimized for
use with the MidQ insert. Pictured on
the graph are the responses of the
woofer and enclosure combination with
the LowQ insert installed; with the MidQ
insert installed; and without an insert
installed (HighQ). The difference in the
performance of the woofer with its
various adjustments is increased output
at and slightly above system resonance
(Fc) with increasing Q, but reduced
output at the lowest reproduced
frequencies. The reduced motor force
supplied by the lower-Q designs results
in reduced sensitivity (SPL 2.83V/1m),
but the effects of that reduced
sensitivity are greatest above 100Hz.
Subwoofers in cars are typically used
for frequencies below 100Hz, so the
reduced sensitivity is inconsequential.
The difference in behavior for vented
and bandpass enclosures is similar, but
the enclosure design is more complex
and should be given special attention.
Although Kappa Perfect VQ subwoofers
were designed with specific uses for the
inserts in mind, there are many different
enclosure and insert combinations
that may suit your taste. The intended
combinations are highlighted as
“optimum” on the charts in the section
titled “Choosing an Application and
Enclosure”; several other applications
are also included.
VARIABLE Q (CONTINUED)
Figure 4. Effects of Variable Q.
Your Kappa Perfect VQ subwoofer is
shipped from the factory without an
insert installed. After determining
which application and enclosure is
most suitable for your system, install
the appropriate insert in the woofer’s
polepiece by aligning the insert with
the hole in the woofer’s polepiece and
simply dropping the insert into place
(see Figure 5).
Figure 5. Installing the insert.
To remove the insert, squeeze the
insert tool to compress the area
between the two tabs, insert the end
of the tool into the vent in the center
of the insert and align the two tabs
with the two small holes inside the
vent. The tabs should lock into the two
holes. Pull firmly on the tool to
remove the insert (See Figure 6).
Figure 6. Removing the insert.
Note: Magnetic force holds the insert in
place. Don’t be afraid to pull hard on the
insert to remove it.
INSTALLING AND REMOVING THE INSERTS
Step 1
Step 2
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