Boston Acoustics MCenter User manual

M Series
Loudspeakers
OWNER’S MANUAL / SAFETY INSTRUCTIONS / COMPLIANCE INFORMATION
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2
IMPORTANT SAFETY INSTRUCTIONS
This symbol found on the apparatus indicates hazards
arising from dangerous voltages.
This symbol found on the apparatus indicates the user
should read all safety statements found in the user
manual.
This symbol found on the apparatus indicates double
insulation.
WARNING!
To reduce the risk of fire or electrical
shock, do not expose this apparatus to rain or moisture.
This symbol found on the apparatus indicates that
the apparatus must be placed in a separate collection
facility for electronic waste and not disposed with
household waste.
1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
4. Follow all instructions.
5. Do not use this apparatus near water.
6. Clean only with dry cloth.
7. Do not block any ventilation openings. Install in accordance
with the manufacturer’s instructions.
8. Do not install near any heat sources such as radiators, heat
registers, stoves, or other apparatus (including amplifiers)
that produce heat.
9. Do not defeat the safety purpose of the polarized or
grounding type plug. A polarized plug has two blades with
one wider than the other. A grounding-type plug has two
blades and a third grounding prong. The wide blade or
the third prong is provided for your safety. If the provided
plug does not fit into your outlet, consult an electrician for
replacement of the obsolete outlet.
10. Protect the power cord from being walked on or pinched
particularly at plugs, convenience receptacles, and the point
where they exit from the apparatus.
11. Only use attachments/accessories specified by the manu-
facturer.
12. Unplug this apparatus during lightning storms or when
unused for long periods of time.
13. Refer all servicing to qualified service personnel. Servicing
is required when the apparatus has been damaged in any
way, such as power-supply cord or plug is damaged, liquid
has been spilled or objects have fallen into the apparatus,
the apparatus has been exposed to rain or moisture, does
not operate normally, or has been dropped.
14. Maintain a minimum distance of 2” (50mm) around the
front, rear, and sides of the apparatus for sufficient ventila-
tion. The ventilation should not be impeded by covering the
ventilation openings or placing on or around the apparatus
items such as newspapers, table-cloths, curtains, etc.
15. No open flame sources, such as lighted candles, should be
placed on the apparatus.
16. The apparatus shall not be exposed to dripping or splash-
ing. No objects filled with liquids, such as vases, shall be
placed on the apparatus.
17.
Either the power inlet connector on the rear of the apparatus
or the power plug at the wall must remain accessible, to be
able to disconnect power from the apparatus.
18. T
o completely disconnect this apparatus from the AC
Mains, disconnect the power supply cord plug from the
AC receptacle.
19. The mains plug of the power supply cord shall remain readily
operable.
American Users:
Note: This equipment has been tested and found to comply with
the limits for a Class B digital device, pursuant to part 15 of the
FCC Rules. These limits are designed to provide reasonable
protection against harmful interference in a residential installation .
This equipment generates, uses, and can radiate radio frequency
energy and, if not installed and used in accordance with the
instructions, may cause harmful interference to radio commu-
nications. However, there is no guarantee that interference will
not occur in a particular installation. If this equipment does cause
harmful interference to radio or television reception, which can
be determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or more of
the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and
receiver.
• Connect the equipment into an outlet on a circuit differ-
ent from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician
for help.
Canadian Users
This class B digital apparatus complies with Canadian ICES-003.
Cet appareil numérique de classe B est conforme á la norme
NMB-003 du Canada.
Use only with the cart, stand, tripod, bracket, or
table specified by the manufacturer, or sold with
the apparatus. When a cart is used, use caution
when moving the cart/apparatus combination
to avoid injury from tip-over.

3
Introduction
Thank you for selecting Boston Acoustics. The M Series family of loudspeakers is designed to deliver exceptionally accurate
and natural sound reproduction from an aesthetically pleasing design. Each M Series model is specifically engineered to
provide superior acoustic results for the intended application.
The M350, M340, M250 and M25 utilize the Extended Wide Bandwidth (EWB) tweeter and Boston Lo-Q™ Cabinet
construction for pure sound reproduction and minimal interference from the cabinet. The MCenter and MSurround utilize
an innovative new Balanced Mode Radiator (BMR) high-frequency driver to provide even sound output over a remarkably
wide area for clear dialog reproduction and an immersive surround-sound field for all listeners. The look of the M Series
includes traditional and modern design cues that provide exceptional sonic results and allow them to easily integrate in a
wide variety of home décors. All of the M Series models are designed to blend seamlessly with each other and to mix and
match with other Boston Acoustics speakers providing great results regardless of the system configuration and speaker
types. We hope that you enjoy your Boston Acoustics purchase for many years to come.
Features
• Second generation Extended Wide Bandwidth (EWB) Tweeter (M350, M340, M250 & M25) to minimize phase shift and
distortion while improving pistonic motion
• Balanced Mode Radiator (BMR) high frequency diver (MCenter & MSurround) to maximize dispersion resulting in improved
dialog intelligibly and surround-sound field immersion for all listeners
• Polypropylene midrange with mass loading (M350 & M340) provides smooth overall response with minimal coloration
in the critical midrange frequencies
• Polypropylene woofers are lightweight and rigid with large motor structures for maximum low frequency output
and heat dissipation
• Boston Lo-Q™ Cabinet Design (All except MSurround & MSubwoofer) to minimize cabinet response and interference
• Leatherette covered baffle (All except MSubwoofer & MSurround in White)
• Rounded cabinet design with premium quality finish
• Solid aluminum stand-offs (M350, M340 & M250)
• 5-way gold-plated precision binding posts
• High quality crossover network filter circuit boards and components
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MCenter MSurround M25 MSubwoofer M250 M340 M350

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Specifications M350 M340 M250 M25
Frequency Range (±3dB): 45Hz – 30kHz 45Hz – 30kHz 60Hz – 30kHz 62Hz – 30kHz
High-Frequency Driver: 1” (2.5cm) 1” (2.5cm) 1” (2.5cm) 1” (2.5cm)
EWB Dome EWB Dome EWB Dome EWB Dome
Mid-Frequency Driver:
4½” (11.4cm) 4½” (11.4cm) 5¼” (13.3cm) —
mass loaded mass loaded polypropylene cone
polypropylene cone polypropylene cone
mid/low driver
Low-Frequency Driver(s): 4 x 5¼” (13.3cm) 4 x 4½” (11.4cm) 5¼” (13.3cm) 5¼”(13.3cm)
polypropylene cones polypropylene cones polypropylene cone polypropylene cone
Crossover Frequency: 400/3,000Hz 390/3,100Hz 450/2,900Hz 3,000Hz
Impedance: Compatible with Compatible with Compatible with Compatible with
8 ohm outputs 8 ohm outputs 8 ohm outputs 8 ohm outputs
Sensitivity: [1 watt (2.83V) at 1m] 90dB 88dB 88dB 86dB
Recommended Amplifier Power
50-500 watts 50-350 watts 50-250 watts 50-200 watts
Dimensions (H x W x D): 423/8x 95/8x 123/16” 4 0 3/8 x 813/16 x 117/16” 3 87/16 x 95/8x 913/16” 1 23/8x 615/16 x 103/16”
(107.6 x 24.5 x 31cm) (102.6 x 22.4 x 29cm) (97.6 x 24.5 x 25cm) (31.4 x 17.6 x 25.8cm)
Weight: 55.9 lbs (25.4kg) 46.3 lbs (21.0kg) 35.3 lbs (16.0kg) 14.7 lbs (6.7kg)
Specifications MCenter MSurround MSubwoofer
Frequency Range (±3dB): 68Hz – 22kHz 95Hz – 22kHz 23Hz – 150Hz
High-Frequency Driver: 2½” (6.4cm) 2½” (6.4cm) —
BMR flat planel BMR flat planel
Low-Frequency Driver(s): 2 x 4½” (11.4cm) 3½” (8.9cm) 10” (25.4cm) polypropylene cone
polypropylene cones polypropylene cone 2 x 8”(20.3cm) polypropylene
cone passive radiators
Crossover Frequency: 700Hz 700Hz 40Hz - 180Hz (variable)
Impedance: Compatible with Compatible with —
8 ohm outputs 8 ohm outputs
Sensitivity: [1 watt (2.83V) at 1m] 87dB 86dB —
Amplifier Power: — — 500 watts RMS
(1000 watts Peak)
Recommended Amplifier Power 50-200 watts 50-150 watts —
Dimensions (H x W x D): 61/8x 215/8x 71/16” 9½ x 69/16” x 47/16” 1 3 1/16 x 163⁄4x 157⁄16”
(15.5 x 55 x 18cm) (24.2 x 16.6 x 11.3cm) (33.1 x 42.5 x 39.2cm)
Weight: 15.9 lbs (7.2kg) 5.5 lbs (2.5kg) 51.8 lbs (23.5kg)
Specifications subject to change without notice.

5
Unpacking the System
Carefully unpack the speakers. If there is any sign of damage from transit, report it immediately to your dealer or delivery service.
Retain the shipping carton and packing materials for future use.
Grilles
The cloth grilles should remain on the speaker during normal use. However, to remove a grille, use your fingers to carefully
pry the top edge of the grille away from the cabinet so you can insert your fingers between the grille and the cabinet. Then
slide your fingers down the inside of the grille frame from top to bottom which will cause the grille to pop free. The grille is
NOT designed to be removed by only pulling on one side. The pins that hold the grille can be damaged. Also, do not use any
objects other than your fingers to remove the grille as the finish or grille may be damaged. Be careful to keep rings, watches
and other sharp objects from scratching the finish or tearing the grille cloth.
To replace the grille, carefully align the two pins at the top of the grille with their corresponding grommets and gently push
them in until the grille is supported by the grommets. Then work your way down the grille gently pushing the grille pins into
the grommets evenly until the grille is fully seated. Be careful to align the pins with the grommets so the cabinet, grille pins
and grommets are not damaged. Also, take care to support the speaker so it does not tip over or fall off its mounting location
while the grille is being removed or replaced. MCenter Note: The same grille removal and replacement procedures apply
to the MCenter except you will begin at the left or right side and work towards the opposite side. MSubwoofer Note: The
MSubwoofer grille is not removable.
Feet & Spikes
The M350, M340 and M250 come with rubber feet installed at the factory which are ideal for hardwood floors. Spikes are also
included for placement on a carpeted surface. To install the spikes, carefully lay the speaker on its back on a soft, debris-free
surface and remove the rubber feet by hand turning them counter-clockwise. Thread the spikes by hand to make sure they
are inserted properly. Save the rubber feet for future use.
The M25, MCenter, and MSurround come with rubber stand-offs that are designed to be attached to the bottom of the
loudspeaker
when stand, shelf or cabinet mounting. This will minimize the vibration transferred from the loudspeaker to the
stand, shelf or cabinet. It will also help to protect the finish of the loudspeaker and the mounting location. The MSubwoofer
comes with rubber feet installed at the factory.
MSurround Note: It is recommended to mount the rubber stand-offs on the back of the side panels of the MSurround if it is
going to be wall mounted. This will minimize the amount of vibration that is transferred directly to the wall. You may need to
adjust the depth of the mounting screws to help ensure that the speaker is not mounted too loosely or too tightly.
Where to Place the Speakers