1. Biro Technology
i n s t r u c t i o n m a n u a l
Kensington
Active Subwoofer

2. 2
Contents
Introduction ..................................................................................... 3
Features ........................................................................................... 3
Placement ........................................................................................ 4
Connection ...................................................................................... 5
Using a single Kensington in a stereo setup .............................................................. 5
Using a stereo pair of Kensingtons in a stereo setup .................................................. 7
Using a single Kensington with a surround-sound or home theater decoder ................ 7
Using a stereo pair of Kensingtons with a surround-sound or home theater decoder .... 8
Adjustment ...................................................................................... 8
Special instructions for using the Kensington with the Biro Technology L/1 .................. 9
Warranty......................................................................................... 10
Specifications ................................................................................ 10
Care ................................................................................................ 10

3. 3
Introduction
The Biro Technology Kensington is a high-perfor-
mance active subwoofer system which when properly
used will provide you with unparalleled listening
pleasure. This manual contains useful guidelines and
other important information that will help you get the
most out of your new product. Please take a few
minutes to review it. We strongly suggest at a mini-
mum that you read the sections on “Placement”,
“Connection”,and"Adjustment" beforeattemptingto
install your new system.
Features
The Kensington is able to set new standards of perfor-
mance for a product of its class through meticulous
engineering, careful cost/benefit analyses, and ex-
tended listening trials. Some of the technical features
you’ll find in the Kensington include:
Built-in active crossover. The on-board active crossover
has been engineered so that integrating the subwoofer
with your existing loudspeakers is simple and seam-
less. Careful filter design assures that the subwoofer
will not be localizable under any reasonable condi-
tions. The crossover is completely defeatable for sur-
round-sound and home theater applications.
Flexible input structure. The Kensington accepts line
level or speaker level inputs. Right and left channel
stereo inputs are internally summed so that a single
subwoofer can be used in conventional stereo or sur-
round-sound application.
Built-in high-power amplifer with active standby. The
Kensington's built-in amplifier can generate over 200
watts of power for plenty of headroom. Input-signal
sensing circuitry automatically turns the amplifier
power on and off.
High efficiency, long-throw 310mm (12") driver with vent-
ed coil and optimally damped 2nd order low-frequency
cutoff. The low-frequency response of the Kensington
has been designed to be free of unnatural sounding

4. 4
Placement
The Kensington may be oriented either vertically or
horizontally. Which makes the most sense for you will
depend on your specific needs and aesthetic tastes. In
either case, the cabinet should be placed on the floor
with the driver side (i.e., the side with the grille cloth)
facing toward the listening area. If you are using it
vertically, the best results are likely to be had if the
cabinet is oriented such that the low-frequency driver
isasclosetotheflooraspossible.Whenpositionedthis
way, the text on the back of the cabinet will be "right
side up".
If you are using only a single Kensington in your
system, locate it midway between the main stereo
loudspeakers(orfrontstereopairinasurround-sound
setup). If you are using a stereo pair of Kensingtons,
place them close to the main stereo loudspeakers (or
front stereo pair in a surround-sound setup). In many
cases a pair of vertically oriented Kensingtons can be
used in leiu of loudspeaker stands.
TheKensingtonisnotmagneticallyshielded.Ifyouare
incorporating it into a home theater system with a
standardtelevisiondisplay,besuretoprovideenough
distance between it and the CRT display so that the
driver's magnetic field doesn't affect it. Typically 60–
100 cm (2–3 feet) will suffice.
You may wish to experiment with placing the Kens-
ington closer to or farther from the rear wall. We
recommend that you start with a spacing of at least 60
cm(2feet).Ifyouthencannotachieveassmoothalow-
frequency response as you desire, moving the cabinet
resonances and will deliver controlled and unfatigue-
ing response to well below audibility.
Underpinning all the design considerations in the
Kensington is the standard Biro Technology credo of
technology in support of music. The motivating force
behind Biro Technology is, quite simply, music. In
everything we do, our goal is to bring the listener
closer to the spirit of the performance.

5. 5
closer to or farther from the back wall may help you
achieve the desired effect. This will change the sub-
woofer's interaction with the room, thereby changing
thenetresponsesomewhat.Exactlyhowitwillchange
will be different for each room, so some experimenta-
tion will be required.
The Kensington's crossover was designed to integrate
seamlessly with any main loudspeaker that has a
reasonablywell-dampedsecond-orderlow-frequency
cutoff. Therefore, for best integration between the
main loudspeakers and the Kensington, we recom-
mend that you plug your main loudspeaker's low-
frequencyports(ifpresent)usingwell-packedfoamor
a similar material. However, if you are using the
Kensington as an LFE device and/or in conjunction
with the bass management functions in a surround-
soundorhometheaterdecoderpluggingtheportswill
likely not be useful.
Connection
Before attempting to connect your Kensington, please
read the section on Placement—especially the last-
paragraph.
All audio connections to and from the Kensington should be
made with the power switch in the OFF position.
The Kensington requires 120 VAC power. Make sure
the power switch is in the OFF position and insert the
AC power cable into the back of the Kensington. Then
connect the other end of the cable to a source of 120
VAC power.
Using a single Kensington in a stereo setup
There are two sets of inputs on the Kensington—one
set will accept line level inputs and the other speaker
level inputs.
If you are using a high-quality stereo preamplifier (or
a receiver or integrated amplifier with a preamplifer
outputs), you may use the Kensington's line level
inputs. If your preamplifier has two pairs of outputs,
simply connect one pair to the pair of LINE IN jacks on

6. 6
thebackoftheKensington.Thenconnecttheotherpair
the the input of your power amplifier.
If your preamplifier has only a single set of outputs,
then you will need to obtain a "Y-splitter" cable from a
cable supplier to give your preamplifier an additional
outputpair.Alternately,youmayconnectyourpream-
plifier's output to the Kensington's LINE IN jacks and
then use the Kensington's LINE OUT jacks to route the
singal back to the power amplifier. The Kensington's
LINE OUT is a direct passive connection in parallel
with the LINE IN jacks (i.e., the LINE OUT signal does
not undergo any processing nor is it passed through
any electronics inside the Kensington.)
(Note: many preamplifiers cannot drive long cables
without compromising performance. If you notice a
degradation in midrange or high-frequency perfor-
mance after connecting the Kensington using the line
inputs, we recommend you experiment with using the
speakerlevelinputsasdescribedbeloworuseapream-
plifier that is not sensitive to cable loads.)
You can use the Kensington's speaker level inputs if:
youdonothaveaccesstolineleveloutputstodrivethe
Kensington, it is inconvenient to wire another set of
line level cables from your electronics to the Kensing-
ton, your preamplifier cannot drive the added load
presented by the additional cables, or your power
amplifer produces a low-frequency coloration that
you like and would like the Kensington to reproduce.
Using good-quality speaker wire (preferably termi-
nated with banana jacks) connect the stereo ouput of
youramplifertotheSPEAKERLEVELINterminalson
the back of the Kensington. Pay close attention to the
polarity of these connections as an incorrect connection can
damage the amplifier driving the Kensington. The connec-
tion to the main speakers can then be made via the
Kensington's SPEAKER LEVEL OUT terminals. These
terminalsareelectricallyinparallelwiththeSPEAKER
LEVELINterminals.(ThustheSPEAKERLEVELOUT
signalsdonotundergoanyprocessinginsidetheKens-

7. 7
ington.) Alternately, you may make the connection to
the main speakers directly from the output of the
power amplifier by using stacking banana plugs or if
yourpoweramplifierhasmorethanonesetofoutputs.
Using a stereo pair of Kensingtons in a stereo
setup
Connecting a stereo pair of Kensingtons is just like
connecting a single Kensington (as described above)
except that only the right channel of your system's
output is connected to the right channel Kensington
and only the left channel of your system's output is
connected to the left channel Kensington. It does not
matter which of the Kensington's LINE IN jacks or
SPEAKER LEVEL IN terminal pairs you use to make
the connections.
Using a single Kensington with a surround-
sound or home theater decoder
If your system employs a surround-sound decoder,
preamplifier, or receiver with low-frequency manage-
ment options, consult that product's manual for setup
instructions. To use the Kensington as an LFE sub-
woofer, connect the LFE output from your decoder to
either of the LINE IN jacks on the Kensington. Then
you may either bypass the active crossover entirely
(LOW PASS control up) or with the active crossover
enabled (LOW PASS control down) increase the fre-
quency control to its maximum (clockwise) position.
Which works best will depend on the performance of
the bass management filters in your decoder.
If you cannot achieve satisfactory results this way, we
recommend you setup the Kensington as described
above under "Using a single Kensington in a stereo
setup" with the front left/right pair as the main speak-
ers. Then use the "route LFE information to mains"
option in your bass management software (if avail-
able).

8. 8
Using a stereo pair of Kensingtons with a
surround-sound or home theater decoder
If your system employs a surround-sound decoder,
preamplifier, or receiver with low-frequency manage-
mentoptions,setuptheKensingtonasdescribedabove
under "Using a stereo pair of Kensingtons in a stereo
setup"usingthefrontleft/rightpairasthemainspeak-
ers. Then use the "route LFE information to mains"
option in your bass management software (if avail-
able).
Adjustment
The material below applies to installations where the
Kensington is being integrated into a conventional
stereo system. If you are using the Kensington as an
LFE device (e.g. in a surround-sound or home theater
system) consult the manual that came with your de-
coder/preamplifier/receiver for setup instructions.
Also read the material on "Using a single Kensington
with a surround-sound or home theater decoder" in
the section above
The Kensington's crossover was designed to integrate
seamlessly with any main loudspeaker that has a
reasonablywell-dampedsecond-orderlow-frequency
cutoff. Therefore, for best integration between the
main loudspeakers and the Kensington, we recom-
mend that you plug the main loudspeaker's low-fre-
quency ports (if present) using well-packed foam or a
similar material. If you are using the Kensington as an
LFE device—e.g. in a surround-sound or home theater
system—then the above does not apply.
If your main speakers employ passive radiators or
haveanelectricallyequalizedlowfrequencyresponse,
it may not be possible to achieve satisfactory integra-
tion. Again, if you are using the Kensington as an LFE
device—e.g. in a surround-sound or home theater
system—this does not apply.
With the Kensington's Crossover switch in the ON
position,theFrequencycontrolatitsminimum(CCW)

9. 9
position, and the Level control at its midpoint, apply
power to the system and subwoofer. Adjust the polar-
ity control and leave it in the position that results in the
most low-frequency output at your listening position.
(If your power amplifier and loudspeakers do not
invertpolarity,theidealpositionforthisswitchwillbe
the 180° position.)
Slowly increase the Frequency control while reducing
the Level control until you achieve a smooth, integrat-
ed response. (It might also be necessary to increase the
level control to achieve the desired effect.)
Note: There is a tendency among many users to set the
FrequencyandLevelcontrolstoohigh.Whenproperly
set, you should not be explicity aware of the presence
of the subwoofer. The only time it should make itself
known is when there is a lot of very low-frequency
information present.
Special instructions for using the Kensington
with the Biro Technology L/1
SincetheL/1isaportedsystem,itwillbenecessaryfor
you to plug its ports using the foam material supplied
- roll it up and insert the roll in the port. The Kensing-
ton's variable crossover was designed so that the Fre-
quency control ideally will be in the minimum (CCW)
position when the L/1s are set up this way. Thus it will
be very unlikely, though not impossible, that you will
needtomovetheFrequencycontrolfromitsminimum
(CCW) position.
Furthermore,theL/1doesnotinvertpolarity,soifyou
are confident that your power amplifier does not in-
vert polarity, the ideal position for the Polarity switch
will be the 180° position. If you are not sure what your
amplifier does to the polarity, then with the Level
control at its midpoint adjust the Polarity for maxi-
mum output at the listening position.
Now simply adjust the Level control for the best bal-
ance.

10. 10
frequency response 25 Hz to 250 Hz ±3dB in free space
driver 310mm (12.2") long throw bass unit with cast
frame and polymer matrix cone.
low-frequency loading 2nd-order sealed box.
crossover 2nd-order lowpass variable from 40 Hz to 150
Hz with additional 2nd-order fixed lowpass at
200 Hz. (Defeatable for LFE applications.)
amplifier power greater than 200 W rms.
inputs stereo or mono line-level input.
stereo or mono speaker-level input.
controls power (off/active standby)
output level
output polarity (0°/180°)
crossover bypass
crossover frequency (42 to 200 Hz)
dimensions h 395mm (15 1/2")
w 725mm (28 1/2")
d 450mm (17 3/4")
specifications are subject to change without notice
Warranty
The Biro Technology product you have just purchased is guaranteed to be free of defects in materials
and workmanship for a period of one year from the date of purchase. If your product should fail within
that time due to a defect in materials or workmanship, BiroTechnology will repair or replace (at our
option) the ailing device and ship it back to you at no charge
Toobtainwarrantyservice,youmustfirstcontactBiroTechnologysothatwecandiagnosetheproblem
and make sure it is necessary for you to send the product back to us. Once we have determined that
we need to have the device back to fix the problem, you must carefully pack the device and send it to
us fully insured using a standard carrier. You must also enclose proof-of-purchase. We cannot accept
deliveries for warranty service that have not been pre-authorized.
Thiswarrantyisnon-transferableanddoesnotcoverdamageduetonormalwearandtear,abuse,and/
or acts of god(s), nor does it cover incidental or consequential damages.
Care
CleantheKensington’scabinetusingonlyasoft,slightly
damp cloth. Any other polish or cleaner may harm the
finish. Do not store or use the Kensington in any area
where the temperature can exceed 50°C (120°F) as
some of the internal adhesives, polymers, and damp-
ing agents may soften. In particular, be careful when
transporting the Kensington since the interior of an
automobile (even the trunk) can become quite hot on a
sunny day.
Specifications

11. 11
POWER
OFF
ON
OUT IN
SPEAKER
LEVEL
IN OUT
LINE
MIN MAX40Hz 150Hz
PHASE LOW PASS
FREQUENCY
LEVEL
ON
OFF
180°
0°
LOW PASS
3A/120Vslow-blowfuse
120VAC
power
red=standby
from
main(front)poweramplifieroutputs
from
preamporprocessoroutput
tomain(front)speakerinputs
tomain(front)poweramplifierinputs
green=on

12. Biro Technology
P.O. Box 582
Circle Pines, Minnesota 55014
(763) 786-6643
http://www.birotechnology.com/
biro@winternet.com
©2000 Biro Technology