Infinity Kappa perfect 10 VQ, Kappa perfect 12 VQ, Kappa perfect 12d VQ User Manual

subwoofer instructions

Thank you for purchasing an Infinity Kappa Perfect VQ

subwoofer. Kappa Perfect VQ subwoofers are engineered to
provide unparalleled audio reproduction at even the highest
output levels, and are constructed using state-of-the-art materials
for unequalled performance and longevity. To ensure the best
subwoofer performance possible, we recommend that a qualified
professional perform the installation. Although these instructions
provide enclosure specifications and explain how to install a
Kappa Perfect VQ subwoofer in a general sense, they do not show
specific box-construction details or vehicle-specific installation
methods. If you don’t feel you have the knowledge, experience
or necessary skills to install the subwoofer yourself, ask your
authorized Infinity dealer about professional installation options.

Remember to keep your sales receipt and this manual in a safe
place so they’re available for future reference.

INTRODUCTION

Kappa Perfect VQ Series subwoofers
are unique because they provide
variable Q. Q adjustments may
allow the subwoofer to be optimized
for a particular enclosure or applica­tion and may provide the user with
optimum performance for several
applications in a single enclosure.

The frequency response of every
speaker includes three distinct regions
characterized by flat amplitude (pass­band), high-frequency attenuation
(stopband-high) or low-frequency
attenuation (stopband-low) (see
Figure 1). Midrange speakers and, to
a lesser extent, tweeters are used to
reproduce frequencies in the region
where they exhibit flat frequency
response. Subwoofers, on the other
hand, are used in a region of low­frequency attenuation, but those low
frequencies are what we want the
subwoofer to reproduce. Subwoofer
system design is almost entirely
an effort to extend the region of
flat response to the lowest possible

frequency or to shape the frequency
response in the band of reproduced
frequencies. Qes and, consequently,
Qts are the parameters that best
describe the behavior of a subwoofer
in the range of frequencies it is most
often used to reproduce.

2

A FEW WORDS ABOUT
POWER HANDLING

The power-handling capability of any
woofer is related both to its ability to
dissipate heat and to the maximum
excursion limits of its suspension.
Once the speaker’s voice coil moves
outside the magnetic gap, power
can no longer be converted into
motion and all the amplifier’s power
is converted into heat in the voice coil.
Voice-coil heating is the greatest
detriment to speaker longevity, so
overexcursion should be avoided.
Since excursion characteristics are
very different for each type of
enclosure, power handling will be
different for each enclosure type.

Sealed enclosures exert the most
control over the motion of the sub­woofer at the very lowest frequencies
because the air inside the box acts
as a spring, opposing the motion

of the woofer’s cone. Larger boxes
allow more excursion, providing more
low-frequency output than the same
woofer in a smaller box, for any input
power level. When placed in a sealed
box much larger than the equivalent
compliance (Vas) of the subwoofer,
it will perform as if it were in an
infinite-baffle application, with the
attendant lower excursion-limited
power handling.

Vented and bandpass enclosures allow
the least excursion for the amount
of sound output (near and above the
resonance frequency of the enclosure).
The mass of air contained in the
port provides an acoustic load to the
woofer’s cone at the tuning frequency,
and this added mass decreases
excursion so that the subwoofer’s
motor is, essentially, coupled to the
air in the port. Vented boxes do not
provide adequate control below the
frequency at which the box is tuned,

so proper design and a subsonic filter
are important. A vented bandpass box
will allow the least cone excursion,
provided a subsonic filter is used.

Infinite-baffle, or “free air,” mounting
allows for greater excursion than does
mounting subwoofers in enclosures.
The power handling of a subwoofer
mounted in an infinite baffle will be
reduced by nearly half its rated-power­handling spec.

Voice-coil overheating and burning
have only one cause – exposure to too
much power for too long. An amplifier
driven into severe clipping or square­wave can output much more average
power than the average power of a
clean sine wave of the same level.
Audible distortion in the sound is a
clear indication of amplifier clipping
and should serve as an indication that
your speakers may be in danger of
being damaged.

VARIABLE Q (PATENT PENDING)

30 10050

Hz

200 1K500 2K 5K 10K

SPL vs Frequency

dBSPL

Deg

180

150

120

90

60

30

0

–60

–30

–90

–120

–150

–180

–10

–15

–20

–25

–30

–35

–40

–50

–45

–55

–60

–65

–70

LOW-FREQUENCY

ATTENUATION

HIGH-

FREQUENCY

ATTENUATION

FLAT AMPLITUDE

Figure 1. Frequency response of a speaker.

3

The operation of a subwoofer (or any
moving-coil loudspeaker) is divided
into two regions. Below resonance,
where the motion of the cone is
“stiffness-controlled,” the subwoofer’s
suspension does a great deal of the
work of opposing the inertia of the
moving assembly – the stiffness of
the suspension controls the motion
of the cone. Above resonance, where
the motion of the cone is “mass­controlled,” the subwoofer’s
suspension has little effect on the
motion of the cone, and the motor
must do all the work of opposing the
inertia of the moving assembly – the
motor controls the motion of the cone.
“Opposing inertia” simply means
starting and stopping the motion of
the cone.

The metal inserts included with your
Kappa Perfect VQ Series woofer are
used to adjust the amount of force the
motor can exert on the inertia of the
moving assembly. The largest of the
two inserts (LowQ), when installed in
the woofer’s polepiece, will provide
the highest motor force and, conse­quently, the lowest Q (see Figure 3).
The smaller of the two inserts (MidQ)
will provide less motor force and
somewhat higher Q and the woofer
used without an insert will have a
much higher Q. (continued)

VARIABLE Q

Figure 3.

20 50Frequency 100 Hz 200 500 1K 2K

Subwoofer Operating Range

dB

95

90

85

80

75

70

65

60

55

OPERATING RANGE

MASS-CONTROLLED

RESONANCE (Fs)

STIFFNESS-CONTROLLED

Figure 2. Subwoofer operating range.