Snell QBx Sub User manual

QBx Sub
Powered Subwoofer
Owner’s Manual

2
IMPORTANT SAFETY INSTRUCTIONS
WARNING: To reduce the risk of fire or electric shock, do not expose this
product to rain or moisture.
The lightning flash with arrowhead symbol, within an equilateral triangle, is intended to alert the
user to the presence of uninsulated “dangerous voltage” within the product’s enclosure that may be
of sufficient magnitude to constitute a risk of electric shock to persons.
The exclamation point within an equilateral triangle is intended to alert you to the presence of important
operating and maintenance (servicing) instructions in the literature accompanying the product.
1. Read Instructions: All the safety and operating
instructions should be read before the product is
operated.
2. Retain Instructions: The safety and operating
instructions should be retained for future reference.
3. Heed Warnings: All warnings on the product and
in the operating instructions should be adhered to.
4. Follow Instructions: All operating and use
instructions should be followed.
5. Water and Moisture: The product should not be
used near water—for example, a bathtub, washbowl,
kitchen sink, laundry tub, in a wet basement, or near
a swimming pool, etc.
6. Carts and Stands: The product should be used
only with a cart or stand that is recommended by the
manufacturer. A product and cart
combination should be moved with
care. Quick stops, excessive force, and
uneven surfaces may cause the product
and cart combination to overturn.
7. Wall- or Ceiling-Mounting: The product should
be mounted to a wall or ceiling only as recom-
mended by the manufacturer.
8. Ventilation: The product should be situated so
that its location or position does not interfere with
its proper functioning. For example, the product
should not be situated on a bed, sofa, rug, or similar
surface that may obstruct the heat sink surfaces,
nor placed in a built-in installation, such as a
bookcase or cabinet that may impede the flow of air
near the heat sink surfaces.
9. Heat: The product should be situated away from
heat sources such as radiators, stoves, or other
products that produce heat.
10. Power Sources: The product should be
connected to a power supply only of the type
described in the operating instructions or as marked
on the product.
11. Grounding or Polarization: This product may
be equipped with a polarized alternating-current
line plug (a plug having one blade wider than the
other). This plug will fit into the power outlet only
one way. This is a safety feature. If you are unable to
insert the plug fully into the outlet, try reversing the
plug. If the plug should still fail to fit, contact your
electrician to replace your obsolete outlet. Do not
defeat the safety purpose of the polarized plug.
12. Power Cord Protection: Power supply cords
should be routed so that they are not likely to be
walked on or pinched by items placed upon or
against them. Pay particular attention to cords and
plugs, convenience receptacles, and the point where
they exit from the product.
13. Cleaning: Unplug this product from the wall
outlet before cleaning. Do not use liquid cleaners or
aerosol cleaners. Use a damp cloth for cleaning.
14. Nonuse Periods: The power cord should be
unplugged from the outlet when left unused for
long periods of time.
15. Object and Liquid Entry: Care should be taken
so that objects do not fall into and liquids are not
spilled into the inside of the product.
16. Lightning: For added protection for this
product during a lightning storm, or when it is left
unattended and unused for long periods of time,
unplug it from the wall outlet and disconnect the
cable system. This will prevent damage to the
product due to lightning and power line surges.
17. Damage Requiring Service: The product should
be serviced if any of the following events occur:
A. The power supply cord or the plug has been
damaged;
B. Objects have fallen or liquid has been spilled
into the product;
C. The product has been exposed to rain;
D. The product does not appear to operate
normally or exhibits a marked change in
performance; or
E. The product has been dropped or the enclosure
damaged.
18. Servicing: The user should not attempt to
service the product beyond what is described in the
operating instructions. For all other servicing,
consult your dealer or contact Snell Acoustics.

3
Declaration of Conformity
Konformitätserklärung
Déclaration de Conformité
Declaración de Conformidad
Verklaring de Overeenstemming
Dichiarazione di Conformità
We/Wir/Nous/WIJ/Noi:
Snell Acoustics, Inc.
143 Essex Street, Haverhill, MA 01832 U.S.A.
declare under sole responsibility that the
product
QBx Sub
to which this declaration relates, is in
conformity with the following standards or
other normative documents: auf das sich
diese Erklärung bezieht, mit der/den
folgenden Norm(en) oder Richtlinie(n)
übereinstimmt; auquel se réfère cette
déclaration est conforme à la (aux) norme(s)
ou au(x) document(s) normatif(s); al que se
refiere esta declaración es conforme a la(s)
norma(s) u otro(s) documento(s) normati-
vo(s): waarnaar deze verklaring verwijst, aan
de volende noem(en) of richtlijn(en)
beantwo-ordt: a cui si riferisce questa
dichiarazione è conforme alla/e sehuente/i
norma/o docu-mento/ i normativo/i.
European Users:
This equipment has been tested and found to
comply with the following European
directive:
(i) EMC Directive 89/336/EEC amending
directive 92/31/EEC 93/68 EEC as per
EN 50081-1: 1992 according to
EN55013: 1990 Class B
EN50082-1: 1997 according to
EN61000-4-2: 1995
EN61000-4-3: 1997
EN61000-4-4: 1995
(ii) Low Voltage Directive (Safety) 72/23/EEC
as per EN60065: 1993

5
SPECIFICATIONS
Frequency Response (±3dB) 35–150Hz
Subwoofer Amplifier Power 100 watts, <0.5% THD, 20–150Hz
Subwoofer Crossover 70–150Hz 24dB/octave low-pass
Crossover Bypass Yes
Bass Unit 10 inch video-shielded woofer
Enclosure Type Ported
Cabinet Construction 3/4-inch walls with internal bracing
Dimensions (HxWxD) 143/8” x 13” x 125/16” (365 x 330 x 313 mm)
Shippping Weight 34 lbs (15.42kg)
Finish Black Painted Oak or Cherry
High quality enclosure
with internal bracing
Conveniently located
bass level control
10 inch video-
shielded woofer
Crossover frequency
control for variable
low pass filtering
Line level inputs
Speaker level inputs

6
PRODUCT DESCRIPTION
The QBx (“Quiet Box”) Sub is a powered subwoofer that delivers the dynamic bass foundation
that is essential for lifelike reproduction of music in the home.
The amplifier in the QBx Sub has a built-in variable crossover that makes it easy to achieve a
seamless blend with the main speakers. A 24dB/octave low-pass filter prevents the subwoofer
from being easily localized by ear, increasing placement flexibility. An external crossover input
is provided for use with home theater electronics that perform their own bass management
functions.
The high-power amplifier and computer-optimized tuning of the QBx Sub enable it to produce
impressive, deep bass at high output levels from a remarkably compact enclosure. In addition, it
features a limiter circuit that tracks the input signal to the subwoofer and prevents the
amplifier from being driven into audible distortion. The benefit: The bass stays clean and strong
at any listening level.
Auto on-off amplifier switching and easily accessible controls make the QBx Sub as convenient
to use as it is exciting to listen to.
CONNECTIONS
NOTE: Power is always supplied to the subwoofer electronics unless it is unplugged. The auto-
on circuitry only activates or deactivates the power amplifier. Make sure your subwoofer and
receiver are unplugged when making the connection.
Line Level
Use the line level inputs with most systems. These inputs accept the line level signal from your
receiver’s subwoofer output. The subwoofer’s circuitry filters out the high frequencies and sends
the remaining low frequencies to the subwoofer power amplifier.
Speaker Level
Use these high-level terminals with receivers that do not have subwoofer output. The speaker
inputs accept both left and right channel speaker signals from your receiver.

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LOW LEVEL INPUTSPOWERCROSSOVER
CROSSOVER
PHASE
HIGH LEVEL INPUTS
FREQUENCY
INT EXT
SUBWOOFER
OUT
0 °
180°
80 Hz
75 Hz 125 Hz
70 Hz EXT
+ LEFT – – RIGHT +
QBx Subwoofer Amplifier Receiver
If you do not wish to run RCA cables to your subwoofer, you may use speaker wire to connect
the subwoofer in parallel with your main speakers. The subwoofer does not present any addi
tional load to your receiver.
Select “subwoofer-no” from your receiver’s set-up menu. This sends the LFE signal to the main
left and right speakers, and thus to the subwoofer. Consult your receiver’s owner’s manual for
more details.
When using the speaker wire hookup, the subwoofer’s built-in crossover is engaged. As a
starting point, set the crossover control on the subwoofer about 10Hz higher than the lower
limit of your main speakers’ bass response. Fine-tune the crossover setting by ear for the
smoothest blend with your main speakers. The best setting of the crossover control will depend
on speaker placement and personal preference.
Be sure to connect “+” to “+” and “–” to “–”.
To main speakers
FRONT
SPEAKERS
Connecting the QBx Sub to a Digital 5.1 Channel Home Theater System
Digital 5.1 home theater electronics dedicate one channel (the “.1” of 5.1) to reproduce the
special low-frequency effects (LFE) information (such as explosions and thunder) contained in
digitally encoded soundtracks.
Select ”subwoofer-yes“ from your receiver’s set-up menu. Hooked up this way, the receiver’s
amplifier is relieved of having to reproduce the difficult low bass signals that can drive the
receiver into audible distortion.
Use an RCA cable (not included), as shown, to connect your digital receiver’s subwoofer output
to the subwoofer. Use the “Crossover Ext” input.

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Connecting Your Subwoofer to Stereo or Dolby® Pro Logic® Systems
For stereo or Dolby Pro Logic systems, the easiest method is to use the same speaker wire
connections as are used for connecting to a 5.1 home theater system. See the illustration at the
bottom of the facing page.
When using speaker wire or the “Crossover Int” input, the subwoofer’s built-in crossover is
engaged. As a starting point, set the crossover control on the subwoofer about 10Hz higher
than the lower limit of your main speakers’ bass response. Fine-tune the crossover setting by
ear for the smoothest blend with your main speakers. The best setting of the crossover control
will depend on speaker placement and personal preference.
CONTROLS
Bass Level Control
This control adjusts the sound level of the subwoofer. It is located behind the grille on the front
of the cabinet. Grasp the top and bottom edges of the grille and pull the grille straight off the
front of the cabinet. A typical setting is for the control is around the 12 o’clock position. See
the information in the preceding sections on connection for more details.
Crossover Control
This control, located on the amplifier panel on the rear of the cabinet, adjusts the frequency of
the low-pass filter for the subwoofer. See the information in the preceding sections on
connection for more details.
Polarity Switch
This switch, also located on the amplifier panel on the rear of the cabinet, selects regular (0°) or
inverted (180°) polarity for the subwoofer. Set this switch to provide the fullest, most dynamic
bass. The distinction of phase will be most audible on low-frequency percussion instruments or
music with a continuously repeating bass line.
NOTE: Power is always supplied to the subwoofer electronics unless it is unplugged. The auto-
on circuitry only activates or deactivates the power amplifier.

9
PLACEMENT
Place the QBX Sub next to a wall or in a corner near your main speakers. Typically, the sound is
best when the subwoofer is within 15 feet (5m) of the main speakers. However, the sharp 24dB/
octave crossover roll-off permits placement farther from the main speakers if necessary. Since
the ear is unable to localize the low frequencies of the subwoofer, the bass still appears to
come from the main speakers.
The level of bass output from the QBX Sub will vary at different positions in a room. When
placed near walls, its loudness is emphasized. Corner placement provides the most bass output,
while placement near only one wall will provide somewhat less bass. Placement completely
away from walls may produce too little bass. Regardless of how you place the QBX Sub, you can
adjust its level with the level control. If you move the QBX Sub, recheck the setting of the
polarity switch. Use the setting that yields the louder and more dynamic sound.
IMPORTANT: Do not place the QBX Sub where there is a chance of contact between the rear
panel amplifier plate and drapes or furniture. Avoid obstructing air flow to the back of the unit.
Corner placement produces the most bass
Wall placement produces less bass
than corner placement

10
LIMITED WARRANTY
During the warranty period, Snell Acoustics will repair, for the original owner, any defect in
materials or workmanship that occurs in normal use of the speaker system, without charge for
parts and labor. The warranty period for all parts of the QBx, except the amplifier, is five (5)
years. The warranty period on the amplifier is one (1) year.
Your responsibilities are to use the product according to the instructions supplied, to provide
safe and secure transportation to an authorized Snell Acoustics service representative, and to
present proof of purchase from an authorized Snell dealer in the form of your sales slip when
requesting service.
Excluded from this warranty is damage that results from abuse, misuse, accidents, shipping,
repairs, or modifications by anyone other than an authorized Snell Acoustics service representa-
tive. This warranty is void if the serial number has been removed or defaced.
This warranty gives you specific legal rights, and you may also have other rights that vary from
state to state.
If Service Seems Necessary
Contact the dealer from whom you purchased the speaker system. If that is not possible, call us
at 978-373-6114, or write to:
Snell Acoustics
143 Essex Street
Haverhill, MA 01832
We will promptly advise you of what action to take. If it is necessary to return your speaker
system to the factory, please ship it prepaid in the original factory packaging. Please note that
Snell Acoustics will not be held liable for shipping damage due to improper packaging. After it
has been repaired, we will return it freight-prepaid in the U.S. or Canada.

©1999 Snell Acoustics. All Rights Reserved.
Specifications are subject to change without notice.
Covered by patents issued and/or pending.
Part #542-1011
143 Essex Street
Haverhill, MA 01832
phone: [phone]
fax: [phone]
email: [email protected]
www.snellacoustics.com