Cambridge Sound Works Powered Subwoofer II User manual

Powered Subwoofer II
by Henry Kloss
Installation and Operating Instructions
© 1995 Cambridge SoundWorks Inc.

Contents
Powered Subwoofer II
by Henry Kloss
Important—Please Read First..........................................................1
Unpacking The System ....................................................................2
Setting Low-Pass Filter Frequency ...................................................3
Cleaning The Cabinets .....................................................................3
Placement ........................................................................................4
Low-Cut Filters ................................................................................5
Audio And AC Power Connections....................................................6
Setting Subwoofer Level And Intial Listening .................................8
Difficulty?........................................................................................8
The Powered Subwoofer II Limited Warranty...................................9

Cambridge SoundWorks
1-800-FOR-HIFI
(1-800-367-4434),
8 AM to Midnight,
Eastern time
In Canada: 1-800-525-4434
Outside US or Canada:
Tel: [phone]
Fax: [phone]
B
Important – Please Read First
ass drums, organs, and
electronic synthesizers are
among the very few
instruments that produce
You should keep in mind
when installing your Powered
Subwoofer II and investigating
its capabilities that you will be
dealing with a relatively
unfamiliar range of sounds.
These are sounds more felt than
heard, and are encountered
more often in the well-equipped
movie theater than in the
concert hall.
Also keep in mind that a
Cambridge SoundWorks Audio
Expert is only a toll-free call
away should you need advice or
assistance (8 AM to midnight
Eastern time):
extremely low-frequency sounds.
As a result, comparatively few
home loudspeakers are designed
to reproduce bass below about
50 Hz.Today, however, home
loudspeakers are called upon to
reproduce more than music: in
home theater systems, they are
called upon to reproduce movie
soundtracks. And modern
movie soundtracks contain a lot
of energy at very low frequen-
cies—on sound effects.
To do full justice to these
effects, as well as to the musical
low-frequencies missed by most
speakers, the Cambridge Sound-
Works Powered Subwoofer II
reproduces, at high power, the
lowest bass sounds the human
ear can detect.
1

2
Unpacking And Checking For Shipping Damage
1. Upon unpacking your
Powered Subwoofer II, please
examine it carefully for any
signs of shipping damage. If
there is evidence of shipping
damage, do not discard the
shipping carton or its inserts,
and do not install or use the
Powered Subwoofer II, in case
it needs to be returned. Call
the store where you made
your purchase or, if you
bought directly from Cam-
bridge SoundWorks, call
1-800-FOR-HIFI immediately.
Your store or a Cambridge
SoundWorks Audio Expert
will tell you how to proceed
and will help minimize any
inconvenience.
2. Check the accessory pack for
the following items (inform
your store or call Cambridge
SoundWorks if there is
anything missing):
• One spare five amp,
fast-blow fuse
• Four square rubber feet
3. We suggest that you keep
the shipping carton and
packing materials in case
you later move, or have to
ship your speakers.

•100 Hz: This position is
appropriate to high-quality
systems with less low-bass
reach, such as those
designed to achieve higher
efficiency at the expense of
low bass.
•140 Hz: This position can be
used with small speakers for
creating your own satellite-
type system. 140 Hz is the
highest frequency recom-
mended for this purpose; the
ear tends to localize sounds
that are higher in frequency.
See page 8 for advice on
how to set the overall subwoofer
level.
If more than dusting is
needed, the vinyl finish of the
Powered Subwoofer II can be
cleaned with a window or vinyl
cleaning product. Avoid
spraying the cleaner directly on
the speaker grilles to prevent
damage to the speaker.
3
The Powered Subwoofer II
has a four position “low-pass”
switch. One of the four settings
of this switch will enable the
Powered Subwoofer II to best
“take over” the very low bass
seamlessly from your existing
speakers. The following
guidelines will help you choose
the appropriate setting for your
system. Alternatively, you may
choose to set the switch by ear.
•55 Hz, 80 Hz: Use one of
these two positions with
Cambridge SoundWorks’
Ensemble®or Ensemble II, or
with any other wide range
speaker system. Typically,
this would be a large
acoustic suspension
bookshelf speaker, where
bass reach has not been
sacrificed for efficiency.
Which switch position to
choose will be affected by
where the main speakers
and subwoofer(s) are placed
in your listening room. The
closer your main speakers
are to the corners of the
room, the more likely the
55Hz setting will be the
better choice. See the
“Placement” section which
follows for more information.
Note: The Powered
Subwoofer II is intended to
supplement, not replace, the
separate woofers supplied
with Ensemble systems.
Do not disconnect your
Ensemble woofers when
using Powered Subwoofer II.
Setting The Low-Pass Filter Frequency Cleaning The
Cabinets

Powered Subwoofer II can be
placed horizontally or vertically
(stick-on feet are provided for
attachment once you have
decided on its final orienta-
tion). It can go most anywhere
within the listening room,
although we don’t recommend
placing it behind the listeners.
It can be hidden under or
behind furniture.
The strength of the low bass
output produced by the Pow-
ered Subwoofer II is markedly
affected by its placement with
respect to adjacent room sur-
faces. The strongest bass will
be reproduced with the speaker
on the floor in a corner (See
Figure 1, C). The least strong
bass will result if the speaker is
placed out in the room away
from the walls. (Figure 1, A.)
We suggest you first place the
subwoofer on the floor against
the same wall as the front
speakers (Figure 1, B). After
extended listening, you can try
other placements if the initial
location results in too much or
too little bass.
1. The ear cannot localize the
very low bass sounds repro-
duced by the Powered
Subwoofer II. This is why it is
possible to use a single unit to
reproduce all the low bass for a
stereo or multi-channel sur-
round system, and why it need
not be located particularly close
to the other speakers or aimed
directly at the listeners. The
Placement
FIGURE 1: HOW ROOM PLACEMENT AFFECTS BASS RESPONSE
Left Satellite Right Satellite
Powered Subwoofer II
SurroundSurround
Left Satellite Right Satellite
Powered Subwoofer II
SurroundSurround
Left Satellite Right Satellite
Powered Subwoofer II
SurroundSurround
A. Least bass B. More bass C. Most bass
4

Note: Do not place the
subwoofer in shelving that
houses a phono turntable.
Strong bass from the speaker,
including the turntable’s own
rumble, could be picked up by
the turntable, fed back out the
speakers again, picked up by
the turntable yet again, and so
on. This condition, known as
acoustic feedback, will muddy
the sound, or worse, set up a
loud, low-frequency rumbling.
2. A listening room’s construc-
tion also has a marked affect
upon the very low frequencies
reproduced by the Powered
Subwoofer II. Thin, relatively
flexible walls allow bass to
dissipate readily, as do open
doors, archways opening into
another room, and even open
windows. In addition, the
larger the room, the greater
the demand for low-frequency
acoustic energy. Therefore, for
best low-bass, the ideal room
for a home theater would be
moderate in size, solidly
constructed, with no openings
to other rooms.
Obviously, not all rooms meet
all these criteria. However, if
you have the option, set up
your home theater in the room
that comes closest. When
listening, shut the room’s
doors and windows if practi-
cal, which can make a surpris-
ing difference. If your listening
room is very large and/or
opens out into another room,
the higher acoustic output of
our original larger Powered
Subwoofer may be necessary
(consult your store or a
Cambridge SoundWorks
Audio Expert).
An option is available from Cam-
bridge SoundWorks to optimize your
system. Low-cut filters keep the low
frequencies best left to the
subwoofer out of the main front
speakers. This “eases” the burden
on front speakers and amplifier,
letting them play more cleanly at
higher levels.
Our inexpensive Low-Cut Filters
are ideal for use with Cambridge
SoundWorks Model Seventeen™,
Model Six™ or Ambiance®speakers,
or other conventional systems of
reasonably wide range. You connect
these filters between your main
speakers and your amplifier. The
filters begin to block bass signals to
your main speakers below about
140 Hz, so that below 100 Hz,
almost no bass signals reach your
main speakers. A filter for your
center channel speaker is not neces-
sary with Dolby®Pro Logic®if you
set its Center Mode control to Nor-
mal (which rolls off frequencies
below 100 Hz).
Low-Cut Filters
• The filters can go at either end of
the left and right speaker wires.
You can, for example, connect
the filters’ INPUT FROM AMP
leads to the speaker terminals on
your receiver or amplifier, then
connect the speaker wires to the
filters’ OUTPUT TO SPEAKER
leads (using the wire nuts
supplied). Or, you can attach the
filters at the back of your
speakers. Connect the OUTPUT
TO SPEAKER leads to the
speaker terminals. Connect the
speaker wires coming from your
amplier to the INPUT FROM AMP
leads with the wire nuts.
• As with all speaker connections,
be sure to maintain consistency
with respect to the + and —
terminals on the receiver and
those on the speakers. The
connecting wires on the filters
are coded by the use of one
copper-colored lead and one
silver.
5

Note: Make all connections with
the Powered Subwoofer II
switched off.
The Powered Subwoofer II can be
connected one of three ways.
Connection Method One: Con-
nect directly to an amplifier or
receiver’s speaker output termi-
nals using conventional speaker
wire (Figure 2). This is the easiest
way to connect the Powered
Subwoofer II and we strongly
recommend it, even if you have a
separate preamp output. You can
use very thin speaker wire, as the
Powered Subwoofer II uses virtu-
ally none of the amplifier or
receiver’s output power. Be sure to
connect the speaker wires to the
same speaker output terminals
used by your main speakers. Do
not use any additional speaker
output terminals your amplifier or
receiver may have.
Alternatively, you may connect
these speaker wires to the termi
6
0
1
2
345
BASS
LEVEL LOWPASS FILTER FREQUENCY (Hz)
55 80 100 140
67
8
9
10
SPEAKER LEVEL
RIGHT INPUT
SPEAKER LEVEL
LEFT INPUT
LINE LEVEL
RIGHT INPUT
LINE LEVEL
LEFT INPUT
0
1
2
345
BASS
LEVEL LOWPASS FILTER FREQUENCY (Hz)
55 80 100 140
67
8
9
10
SPEAKER LEVEL
RIGHT INPUT
SPEAKER LEVEL
LEFT INPUT
LINE LEVEL
RIGHT INPUT
LINE LEVEL
LEFT INPUT
0
1
2
345
BASS
LEVEL LOWPASS FILTER FREQUENCY (Hz)
55 80 100 140
67
8
9
10
SPEAKER LEVEL
RIGHT INPUT
SPEAKER LEVEL
LEFT INPUT
LINE LEVEL
RIGHT INPUT
LINE LEVEL
LEFT INPUT
INTEGRATED AMP OR RECEIVER
(FRONT)
SPEAKER OUTPUTS
LEFT RIGHT
To left (front)
speaker To right (front)
speaker
PREAMP
OUTPUTS TO POWER AMP
LR
“Y”
Adapters
To left and right
power amp inputs
*Labeled “Mono”
on some units
SURROUND DECODER, RECEIVER OR PREAMP
POWERED SUBWOOFER II POWERED SUBWOOFER II POWERED SUBWOOFER II
Figure 2. Using speaker wire. Figure 3. Using“Y” adapters
and phono cable. Figure 4. Using a full-range signal output.
OUTPUTS
L
FRONT CENTER
R
SURROUND SUBWOOFER*
Stereo phono cable
Audio And AC Power Connections

nals of your main speakers
instead of the amplifier or
receiver’s speaker output termi-
nals.
Be sure the speaker wire con-
nects the positive (+) terminals of
the subwoofer to the positive (+)
terminals of the amplifier or
receiver (and similarly connects
the negative (–) terminals to-
gether). All two-conductor speaker
cable is coded along one conduc-
tor by lettering, a stripe or a raised
bead -or- the appearance of the
two conductors differs, usually
one copper and one silver. This
allows you to easily connect the
proper conductor to each terminal.
Connection Method Two:
Connect between a stereo preamp
output and a stereo power amp
input using phono cable “Y”
adapters and standard shielded
stereo cable with phono plugs
(Figure 3). Some receivers and
integrated amplifiers have preamp
outputs and power amp inputs
7
time, such as for several weeks’
vacation, it’s a good idea to turn
the Power switch off.
Note: The 5A fast-blow fuse
protects the amplifier from shorts
across its output, or within its
output stages. If it blows, try
another fuse of exactly the same
value, such as the one supplied in
the accessory pack (do not use
any other value or a slow-blow
fuse). If the fuse blows again,
there may be a defect within the
unit. Do not replace a fuse more
than once. Contact your store or a
Cambridge SoundWorks Audio
Expert as soon as possible for
advice. There are no other fuses
within the Powered Subwoofer II.
Note: If you connect the Powered
Subwoofer II to your system using
speaker wires and hear a low-level
hum, turn off both the system and
the subwoofer and reverse the
latter’s AC plug in the outlet.
When you turn the system back
on, the hum should be gone.
that are accessible by removing
jumpers from the back panel.
Connection Method Three:
Connect from a subwoofer output
(on either a receiver, amplifier,
preamp or surround unit) using a
single shielded cable with phono
plugs at each end (Figure 4). The
subwoofer output should be a full-
range mono signal. Check the
specifications for the subwoofer
output. Do not use a subwoofer
output that cuts off the signal
above some arbitrary frequency
(usually between 80 and 200 Hz).
This kind of signal output will
conflict with the operation of the
Powered Subwoofer II’s internal
electronic crossover, resulting in
poor performance. Assuming you
have the necessary full-range
output, use either the left or right
line input of the Powered
Subwoofer II.
Note: You should connect the
Powered Subwoofer II to your
system using either the line level
inputs or the speaker level inputs–
but not both sets of inputs.
AC Power, On/Off Switch,
and Fuse
After you have finished making
the audio connections, plug the
Powered Subwoofer II’spower cord
into any convenient 120-Volt AC,
60 Hz outlet, and switch the
power “On”.
Note: Do not plug the Powered
Subwoofer II into a “switched”
outlet on the back of your receiver
or amplifier. The Powered
Subwoofer II draws enough power
at higher volume levels that it
could damage the outlet’s relay
device.
You can safely leave the
Powered Subwoofer II turned on all
the time, although it does draw a
small amount of power even
when you aren’t playing music.
However, if you are leaving your
system unattended for a long

If you experience any diffi-
culty, don’t hesitate to call the
store where you made your
purchase, or a Cambridge
SoundWorks Audio Expert. If a
problem is confirmed, you will
need to return the speaker to
that store or its Authorized
Service Center. If you purchased
the speakers through our mail
order catalog service, call a
Cambridge Sound-Works Audio
Expert at 1-800-367-4434. He or
she will help you track down the
problem, which could be in some
other component in your system.
If together you agree that there
is something wrong with the
Powered Subwoofer II, he or she
will supply you with a Return
Authorization Number and a
shipping carton specifically for
the unit. Please do not return the
Powered Subwoofer II to the
factory without prior authoriza-
tion.
The Subwoofer Level control
adjusts how loudly the Powered
Subwoofer II plays. Start with it
set midway (5) then adjust
upward or downward depending
on what you discover during
your listening tests.
Remember that the Powered
Subwoofer II reproduces frequen-
cies below most frequencies of
musical interest. Therefore, it’s
easiest to adjust the subwoofer’s
output when listening to film
soundtracks on video cassette or
Laser Disc. Film soundtracks
generally have deeper bass
signals recorded on them than
the average compact disc.
In order to evaluate the Pow-
ered Subwoofer II’s contribution
and make final adjustments, try
sound effects such as the semi
hitting the concrete after a 20-
foot fall in “Terminator 2,” the
heavy-footed killer robot in
“Robocop,” or the stomping of
the T-Rex in “Jurassic Park.”
With the Powered Subwoofer II
properly adjusted, these film and
video sound effects should liter-
ally be room-shaking at high
playback levels. In contrast, the
majority of music should not
sound any different with the
Powered Subwoofer II properly
adjusted. Indeed, if the sub-
woofer does add any “boomy” or
“thumpy” quality to music, you
may have the subwoofer’s level
control set too high.
Always adjust the level control
first. Fine tune the low-pass filter
setting once you have arrived at a
satisfying overall level control
setting.
It may take several sessions
using different films and musical
sources to arrive at just the right
adjustment.
8
Setting Subwoofer Level And Initial Listening Difficulty?