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Kappa Perfect was conceived and
introduced in 1998 as a high-end line
of car audio products. Infinity’s claim in
1999, when Kappa Perfect Subwoofers
were originally released, was that it had
the longest one-way linear excursion of
any subwoofer on the market. Additionally,
Kappa Perfect subwoofers incorporated a
somewhat higher Qts than other sealedbox woofers available at the time, which
made them appropriate for use in small
sealed and vented boxes. The Perfect 12d
VQ represents the latest generation of
“Perfect” (no modesty here) subwoofers.
Built on a proprietary four-spoke cast
frame design, the dual voice coil 12d VQ
weighs in at a healthy 22 lbs. The frame is
well conceived and has four sets of vents
below the spider that provide for substantial airflow out of the top plate voice
coil/gap area. This cooling mechanism is
further enhanced by the heat sinking
aspect of the frame. Besides cooling, the
frame is also set up to provide for substantial rearward spider travel and has nearly
1.5 inches from the integral spider mounting shelf to the back of the frame.
The motor system used on the 12d VQ
is pretty unique and patent pending. “VQ”
stands for Variable Q. Virtually all woofers
you see reviewed in CA&E have a fixed Q
(short for Qts, the number used to
describe low-frequency performance of a
speaker). Infinity engineers, however,
came up with a clever
way to allow a user to
personally customize
and optimize the Q of
his subwoofer for specific applications
from small sealed boxes to larger vented
or bandpass boxes and even infinite baffle
applications. This is accomplished with a
system of magnetically conductive 2.5inch-diameter milled steel “inserts” that fit
into the pole piece area of the backplate,
which is a milled T-yoke type with a 3mm
pole extension. Two inserts marked Mid Q
and Low Q are supplied with the Infinity
WWW.CARAUDIOMAG.COM
TESTREPORT:.
TEXT > VANCE DICKASON & ERIC HOLDAWAY :: PHOTOGRAPHY > STEVE SAWITZ
KAPPA PERFECT
12d VQ SUBWOOFER
Variable Q Makes This An Extremely Versatile Sub
THE AUTHORITATIVE ELECTRONIC SOURCE
ELECTRONICALLY REPRINTED FROM NOVEMBER 2003
INFINITY
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12d VQ that allow for the three possible
variations, High Q (no insert), Medium Q
and Low Q. High Q (a Qts of about 0.6) is
attained by using no insert at all and just
having a gaping 2.5-inch hole in the back
of your woofer. The Mid Q insert (Qts in
the 0.47 range) is the shortest of the two.
It’s only 1.875 inches long and has a
1.125-inch-diameter pole vent. For Low Q
alignments (Qts about 0.32) you need to
install the largest of the two inserts. It
measures about 2.875 inches in length
and has a smaller pole vent that is only 1
inch in diameter. Since the two steel
inserts are magnetically conductive, getting them in and out of the motor backplate would be a serious challenge had
Infinity not provided an insert “puller”
tool. The tool is a sort of wire handle with
ends that fit into two small holes in the
sides of the pole vent area. For the technically curious, the inserts affect the measured Qts of this woofer in two ways.
First, Qts of a woofer is a primary function of the motor strength (usually
described by the Bl number you see in the
data charts). The stronger the motor, the
lower the Qts (it’s not quite that easy, but
kind of). The Low Q insert is the longest
with the smallest vent and therefore has
the most magnetically conductive material
added to the motor system. This increases
the amount of magnetic flux available to
voice coil gap (think of it as a nitrous tank
for your woofer). Likewise, the Mid Q
insert has less conductive material because
it’s shorter and has a bigger pole vent, so
produces somewhat less magnetic gap flux
and results in a Qts higher than the Low
Q insert. The High Q setting comes from
no insert at all, which means less magnetic flux and thus a higher Qts number. The
other affect is really secondary and concerns the amount of series resistance
caused by the air flow restriction out the
pole, which in turn affects the speaker’s
compliance in free air.
Horsepower for this ride is provided by
two stacked magnets, sandwiched between
the milled and polished 10mm-thick front
and back plates. Together the plates and
magnets create the magnetic field that drives the 3.2-inch-diameter voice coil. The
voice coil consists of two 2-layer CCAL
(copper clad aluminum) round wire windings on a non-magnetically conductive
Kapton former. Engineering at Infinity is
pretty much state-of-the-art and the company used a good deal of computer software to design this motor system. This
included a FEA (Finite Element Analysis)
modeling program called Maxwell, LEAP
CAD software like I use in CA&E reviews,
the MLSSA fft analyzer and the relatively
new and very serious big gun for analyzing woofer large signal performance, the
Klippel analyzer.
All of this drives a new proprietary
metal cone made from a magnesium alloy
Infinity calls M
3
D or Magnesium Metal
Matrix Diaphragm. According to the literature, this material is 20 times “deader”
than aluminum cones and has superior
stiffness and damping compared to other
materials. With a 5-inch-diameter dust cap
made from the same material that reinforces the cone at its midpoint, the slightly curved M
3
D cone is indeed quite stiff.
However, I was surprised that the outside
rim wasn’t turned downward, which is
often seen with aluminum cones and also
enhances their stiffness. I’m guessing this
has to do with the bending quality of the
magnesium compound.
Part of the compliance for this woofer
is supplied by a fairly wide (1 inch)
nitrile-butylene-rubber (NBR) injectionmolded surround with integral front
mounting gasket. Remaining compliance
is provided by a 7-inch-diameter polyester
and cotton blend progressive roll spider
with the voice coil tinsel lead wires
stitched to its surface. And lastly, each
voice coil is terminated by a pair of gold,
color-coded binding posts.
IN THE LAB
As promised in my last review, this
review incorporates the use of the new
LinearX LEAP 5.0 Enclosure Shop large
signal parameter calculation and simulation technology. Equipment used was
similar to previous reviews, but has a
couple of important changes. The same
LinearX LMS analyzer with Windows
software was used to make both free-air
and added mass impedance measurements. And, as before, this was not done
using standard impedance techniques,
which include a large series resistance, but
by measuring the driver directly coupled
to an amplifier, using the LinearX VIBox
to measure both current and voltage separately and then using Ohm’s Law to divide
FIGURE 1. SEALED
DATA CHA RT
Brand . . . . . . . . . . . . . . . . . . . . . . . . . . . .Infinity
Model . . . . . . . . . . . . . . . . . . . . . . . . . . .12DVQ
MSRP . . . . . . . . . . . . . . . . . . . . . . . . . .$444.95
Warranty . . . . . . . . . . . . . . . . . . . . . . . . .3 years
MECHANICAL SPECIFICATIONS
Weight . . . . . . . . . . . . . . . . . . . . . . . . . .22 lbs.
Rear Mounting Clearance . . . . . . . . . . . . . .6.813”
Woofer Magnet Dim. (dia. X ht. In mm) . . .178x22x2
(2 stacked magnets)
Voice Coil Diameter . . . . . . . . . . . .81.9mm (3.2”)
Voice Coil Winding Layers . . . .4 (two 2 layer coils)
MEASURED T/S PARAMETERS
Nominal Impedance (ohms) . . . . . . . . . . . . . . . .2
Revc (ohms) . . . . . . . . . . . . . . . . . . . . . . . .1.79
(both 3.58-ohm voice coils connected in parallel)
Sd (cone area in sq. meters) . . . . . . . . . . .0.035
LOW Q MID Q HIGH Q
Bl (motor strength in Tesla Meters)
. . . . . . . . . . . . . .11.70 . . . . .9.53 . . . . . .7.81
Vas (in liters) . . . .94.27 . . . .94.24 . . . .110.24
Cms (micrometers per Newton)
. . . . . . . . . . . . .298.72 . . .298.60 . . . .349.35
Mms (grams) . . .195.25 . . .195.37 . . . .173.97
Fs (Hz) . . . . . . . . .20.84 . . . .20.84 . . . . .20.42
Qms . . . . . . . . . . . .6.30 . . . . .6.58 . . . . . .6.52
Qes . . . . . . . . . . . .0.33 . . . . .0.50 . . . . . .0.66
Qts . . . . . . . . . . . .0.32 . . . . .0.47 . . . . . .0.60
POWER AND EXCURSION DATA
Sensitivity (2.83V/1M in dB)
. . . . . . . . . . . . . .92.2 . . . . .90.41 . . . . .89.66
Continuous Power Handling (watts RMS)
. . . . . . . . . . . . .400 . . . . .400 . . . . . . .400
Peak Power Handling (watts)
. . . . . . . . . . . .1600 . . . .1600 . . . . . .1600
Xmax ([coil length – gap height]/2 in mm)
. . . . . . . . . . . . . .15.5 . . . .15.5 . . . . . .15.5
COMPUTER SIMULATION DATA
Enclosure size for simulation (cubic feet)
Sealed (Mid Q insert) . . . . .1.0 (50% fill material)
Vented (Low Q insert)1.75 tuned to 32Hz (15% fill)
-3dB (F3) at 2.83V
Sealed . . . . . . . . . . . . . . . . . .(Qtc=0.89) 41.4Hz
Vented . . . . . . . . . . . . . . . . . . . . . . . . . .34.8Hz
Voltage to achieve Xmax + 15%
Sealed . . . . . . . . . . . . . . . . . . . . . . . . . . . .40V
Vented . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43V
SPL at Xmax + 15% (17.8mm)
Sealed . . . . . . . . . . . . . . . . . . .115.5dB anechoic
Vented . . . . . . . . . . . . . . . . . . .117.5dB anechoic
SPL in-car measurement at 2.83 volts, 1 meter Peak
reading non-weighted
40 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . .98.0 dB
80 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . .99.3 dB
Max SPL . . . . . . . . . . . . . . . . . . . . . . . .128.0 dB
FIGURE 2. VENTED
52: SPL sd 40V 154cf
62: SPL vt 2.83V 154cf
SPL vs Freq
SPL vs Freq
dBSPL
130
125
120
115
110
105
100
95
90
85
80
10 Hz 20 30 40 50 60 70 80 90 100 200 300 400 500
43: SPL sd 2.83V 41.4Hz
47: SPL sd 40V
Map
51: SPL sd 2.83V 154cf
dBSPL
130
125
120
115
110
105
100
95
90
85
80
10 Hz 20 30 40 50 60 70 80 90 100 200 300 400 500
53: SPL vt 2.83V
57: SPL vt 43V
Map
61: SPL vt 43V 154cf
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into this product. As Andy kept reminding
me, “This is the first subwoofer that can
be easily optimized for tiny sealed boxes,
moderately sized sealed and vented and
infinite-baffle applications.” Once I got
Andy back to earth, we settled on a sealed
0.7-ft3 enclosure for sound quality.
INSTALLATION
I had my guys at Speaker Works build a
0.7-ft3 enclosure, but as you will read
later, I ended up building and using the
12d VQ in a 1.0-ft3 enclosure for all of the
final listening. Once I got the Perfect 12d
VQ into its enclosure, I headed out to my
Ford F-350 Super-Duty truck. In the Ford,
I found that the 12d VQ worked well in
most locations, but it really kicked butt
with the enclosure placed on the floor
between the front and back seat, subwoofer facing up.
The 12d VQ is rated at 400WRMS for
power handling and 1400 watts of music
power. To power the subwoofer, I
installed two Crossfire VR1000D amplifiers with a bridging module. Doing this
will allow me to wire the 12d VQ’s dual
4-ohm voice coils in parallel for a 2-ohm
load. Two Crossfire VR1000D amplifiers
wired with a bridging module at 2 ohms
will deliver a throbbing 2000 watts of
power! I used the internal crossovers
from the amplifiers and bypassed the subsonic filters.
ADJUSTABLE Q — DOES IT
DO ANYTHING?
The first thing I wanted to
find out was if this adjustable
Q thingy was just a bunch of
marketing Barbara Streisand.
For this section of the test I
mounted the 12d VQ inverted
so that the magnet was on the
outside of the enclosure.
By changing these inserts,
we are changing the amount
of magnetic force (Bl) applied
to the voice coil. The Low Q
insert is the largest and it
produces the highest Bl prod-
voltage by current to get impedance. The
biggest difference is how this is accomplished (see Web version for more information at www.caraudiomag.com).
Parameters shown in the Data Chart
were used to produce computer simulations of two factory-recommended box
volumes, one using the Mid Q insert and
one using the Low Q insert. The sizes
chosen from the factory selection were a
1.0-cubic-foot sealed box using the Mid Q
insert and a 1.75-cubic-foot vented box
using the Low Q insert and tuned to 32Hz
with a 4-inch-diameter port.
Performance in the 1.0-cubic-foot sealed
box produced a low-frequency rolloff of
41.4Hz with a box Qtc of 0.89. My preference would be to stuff this box a little more
or make it somewhat larger to drop the
small signal Qtc of the box down to about
0.7. This should translate to somewhat
more accurate bass that will still sound
good at very high volume levels. However,
increasing the voltage input of the 1.0cubic-foot sealed box computer simulation
to 40V increases the excursion to its maximum linear level (about 17.8mm) and
results in an output of 115.5dB. This is a
reasonably impressive number considering
the woofer is still operating more or less
linearly at this point.
The vented box simulation had a lower
F3 of 34.8Hz and a higher max linear SPL
of 117.5dB. These numbers are based on
sine wave analysis and the performance
with program material will probably be at
least 2-3dB greater before noticeable distortion. However, like most of the sophisticated subwoofers in this price range,
they are easily capable of producing
undistorted sound pressure levels high
enough for you to want to own an SPL
meter so you’ll know exactly what SPL
you are subjecting your ears to.
Along these lines, if you look at the
LEAP 5.0 graphs you will see that something new is being displayed. Both graph
sets, Fig. 1 for the sealed box and Fig. 2
for the vented box, have double sets of
curves that represent the SPL in an anechoic chamber (red at 2.83V and black at
max voltage) and a second set that represents the response in a car compartment
(blue at 2.83V and green at max voltage).
In this case, I used a 154-cubic-footer for
the compartment size, about the size I calculated for my Eclipse GT. While the anechoic SPL maximums before severe distortion were 115.5dB sealed box and 117.5dB
vented box, you can see that in a small
car, these figures get much higher — a
minimum of at least 7dB higher SPL! This
number changes with the car volume and
the peaks occur in different places, but
that at least gives you some idea of the
real world SPL when you are sitting in
your car and cranking up the volume.
Infinity is offering a lot of trick technology with this subwoofer. The variable
Q concept is definitely cool, and if nothing else inspires confidence in the high
quality of engineering that Infinity is capable of. But, as usual, in the end, it all
comes down to the subjective sound quality. So what’s up with that? —V.D.
SUBJECTIVE
Well Vance, you are right about this
subwoofer being crammed full of high
technology. This awesome variable Q
design is from someone who is really
thinking outside of the box! And as you
will read further along, it works.
To get the low down on this highly
sophisticated subwoofer, I spoke to Andy
Wehmeyer, Infinity’s Product Marketing
Manager Guru-Kinda-Guy. I asked Andy
what enclosure type and size he recommended for the test, and I ended up with
a half dozen boxes and alignments before
I finally had to tell Andy that I was not
going to test them all! In about 10 seconds he had given me a couple of sealed
alignments, at least three ported and even
a free-air design.
This just goes to illustrate the incredible versatility that Infinity has designed
Points Infinity
Possible 12d VQ
Overall Sound Quality 50 40
Tonal Balance 10 8
Low Frequency Extension 10 7
Clarity at Low Volume 10 8
Clarity at High Volume 10 8
Impact 10 9
TOTAL 100 80
SUBJECTIVE SCORE CHART
Artist Music Points Infinity
& Title Type Possible 12d VQ
Lenny Kravitz Rock 10 7
Believe in Me
Sade Smooth 10 6
Lovers Rock
10,000 Maniacs Folk Rock 10 6
Peace Train
Creed Rock 10 8
Say I
Harry Connick Jr. Vocal Jazz 10 8
We Are In Love
TOTAL 50 35
MUSIC SELECTION
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uct. Having a higher Bl product means
you have more available force to move the
cone, but it requires a more powerful
counter force to help control the movement of the cone. By going to a smaller
enclosure, we have a tighter or stiffer air
spring that the woofer cone is working
against. As the Q of a subwoofer goes up,
the Bl factor drops and you need a larger
and larger enclosure to soften the air
spring. If you do not soften the air spring,
the stiffer air spring will start to override
the ability of the motor to properly control the movement of the cone, resulting
in higher distortion and possibly damaging the sub. So as I am raising the Q of
the 12d VQ, I will be expecting some pretty obvious changes in the sound quality
because we will be moving radically away
from the correct size enclosure.
I installed the Low Q magnet insert to
begin. With this insert the 12d VQ should
be optimized for the 0.7-ft3 enclosure that
we are using. It sounds really tight and
punchy, and hits hard.
I pulled the Low Q insert and installed
the Mid Q one. The bass is now a bit looser. Not as tight, but the low frequency
extension does appear to be slightly better.
The power handling also has taken a step
down. So now I go for the High Q setting
by removing the insert altogether. First
impressions were that the overall efficien-
cy was now lower and that the bass
impact response had radically changed. It
was just out and out loose, with a lot of
hangover. The power handling was way
down and the woofer was just screaming
that it was in the wrong enclosure, which
of course it now was. Well, what do you
know, this adjustable Q thing does work.
Awesome! One subwoofer that can be
tuned to match many different applications — I am getting excited.
OK, enough playing around, let’s get to
the listening! I reinserted the Low Q plug
and mounted the 12d VQ in the enclosure
the correct way. Then I cranked up Lenny
Kravitz’s album Lenny, track five, “Believe
In Me.” This track has a great opening
bass line and a tightly recorded drum kit
that will really exercise a subwoofer. At
80Hz the 12d VQ is loud and delivers
chest-pounding impact. From 60Hz and
below, the loudness level of the bass line
falls off slightly. The 12d VQ definitely has
a hump at about 80Hz and can tend to
sound a little one note-ish. But the 12d
VQ is not muddy like some of the other
subwoofers that I have tested. I tried a
number of tracks quickly and decided to
try the 12d VQ in a larger enclosure, a
1.0-ft3 sealed.
The results were immediate. The upper
bass hump is now much smoother and the
low frequency extension is greatly
improved with this slightly larger enclosure. The 12d VQ produced impressive
impact and clarity. Imaging is good and
mostly up front.
Next I listened to Sade’s Lovers Rock
album, the title track. This track has a bass
line that moves from 80Hz to below 40Hz,
and the upper frequency bass note hump is
again noticeable, but not overpowering. A
touch of equalizer, a slightly larger enclosure or possibly lowering the crossover frequency may correct the response curve.
From 0:53 to 1:00, there is a declining
scale of bass notes. The 12d VQ reproduces these note changes with authority
and ease. It has excellent impact response
and gave me a good shaking.
Next I put in 10,000 Maniacs’ “Peace
Train.” The opening eight bars of this
track have a deep 30Hz kick drum beat,
one beat per bar. It’s perfect for highlighting subwoofer impact and hangover, if
there is any. The kick drum impact is
very firm but it is missing the really deep
fundamental note. Hangover is again
minimal and the overall performance is
great.
Next up is Creed’s Human Clay album,
track four, “Say I.” After about 20 seconds,
I found myself thinking that the 12d VQ
is geared for rock music. The bass line
came through super fast and tight. A lot of
kids that I work with are asking for subwoofer systems that have “fast bass.” Well,
the Infinity 12d VQ has moved to the top
of my list of recommendations.
I finished off with a listen to the title
track off an old favorite album, Harry
Connick Jr.’s We Are In Love. It features a
fine recording of a closely mic’ed stand-up
string bass. The bassist is getting a workout in this recording, going up and down
the scale. The Infinity Perfect 12d VQ
reproduces the attacks of the string plucks
with great authority. I could feel them in
my chest, and the note shifts are clearly
defined and controlled.
CONCLUSION
Is this subwoofer the answer to all of
your bass wants and needs due to its amazing versatility? It very well may be. It’s a
wonderful sounding sub with excellent
detail and sound quality. It can be used in
just about any type of enclosure, from a
tiny sealed box to a moderately sized sealed
or a vented, and even in an infinite-baffle
application. All of that ability in one subwoofer? Impressive for sure. —E.H.
v
Christopher M. Dragon
Director of Brand Marketing
(516) 682-6489
www.jbl.com
Posted with permission from the November 2003 issue of Car Audio & Electronics ®
Copyright 2003, PRIMEDIA Inc. All rights reserved.
For more information about reprints from Car Audio & Electronics, contact Wright’s Reprints at 877-652-5295
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