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Bose 251 TM Environmental Speakers Manual


Bose 251 TM Environmental Speakers Manual

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Setting Up Bose 251 TM Environmental Speakers

Before you begin Bose 251 
Thank you for purchasing Bose® 251TM environmental speakers. These high-performance outdoor speakers are engineered to provide sound quality far beyond that of other environmental speakers. The 251 environmental speakers are designed to withstand nature’s elements – so you can be confident they will perform for years to come.

Unpacking the carton
Carefully unpack your speakers and save all packing materials for possible future use. Check that your system contains the parts identified in Figure 1. Do not attempt to use your speakers if any part of them appears damaged. Instead, notify Bose Corporation or your authorized Bose dealer immediately.
WARNING: To avoid the danger of suffocation, keep plastic bags out of the reach of children.

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Tools required

You need the following items to complete this installation:

  • Speaker wire (see “Wire recommendations” on page 13)
  • Phillips-head screwdriver (#2)
  • A drill with the following bits:
    • A 3⁄ 32 inch diameter (2,5 mm) bit is preferred, or you can use a 1⁄ 8 inch diameter (3,0 mm) bit. For concrete, a 1⁄ 4 inch (6,0 mm) diameter masonry bit can be used.
  •  Eye and ear protection
  •  Dust mask

CAUTION: Failure to follow the instructions in this owner’s guide voids all warranties on your speakers. If you are unsure of your ability to complete this process, consult a professional installer.Please read this owner’s guide completely before beginning installation.

Selecting the location for your speakers

For best results, mount both speakers on the same wall, facing the listening area. Make sure they do not face each other. (Outdoors, if you are not using an existing wall, consider the length of your listening area as your “wall.”)
The 251TM speakers should be placed at least 7 feet (2 m) apart.Please consider the following before mounting your speakers:

  •  Measure the length of speaker wire you need to connect each speaker to your receiver or amplifier. To determine the wire gauge you will need, refer to the “Wire recommendations”.
  • It is important that the speaker wire not be tripped over, pinched, or pulled. Determine the best route to protect the wire.

CAUTION: Do not mount on surfaces that are not sturdy enough, or that have hazards concealed behind them, such as plumbing or electrical wire. If you are unsure about installing these speakers,contact a qualified professional installer.

  •  Regardless of where you place your speakers, make sure they cannot fall and cause injuries.
  •  Bose® 251 speakers are not magnetically shielded. Keep them at least 9 inches (23 cm) from any video screen or monitor.

Note: This product is not intended for use in areas where it will be subject to high vibration. If you are unsure about installing these speakers, contact a qualified professional installer.

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Installing Your 251 TM Speakers

Choosing the speaker wire
Be sure to use the proper gauge (thickness) of speaker wire. Standard zip cord (2-conductor,18-gauge wire found at electrical and hardware stores) works for most applications. If your speakers will be more than 30 feet (9 m) from the receiver or amplifier, see the “Wire recommendations”under “Technical Information” on page 13. Or check with your authorized Bose® dealer.If you decide to run the speaker wire through a wall or underground, check your local building code requirements, or contact an electrical installer before proceeding.
Note: Be sure to cut enough wire to reach from the receiver to each speaker.
CAUTION: Before making any connections, turn off your receiver or amplifier and unplug it from the outlet (the AC power mains).

Installing the mounting brackets

The 251TM speakers should be mounted using the supplied brackets. They can be mounted onto the exterior of a house or onto a deck railing or table. If you choose not to use the supplied brackets, be sure to position your 251 speakers on a sturdy surface.
CAUTION: If you do not use the supplied brackets, choose a level surface for the speakers. Vibration can cause the speakers to move, so it is important that you install the supplied rubber feet before using the speakers on a surface. Refer to “Attaching the rubber feet” on page 11.

Installing the brackets onto the exterior of a house
The 251 speakers should be mounted in a vertical position to achieve the best musical performance. Figure 3 illustrates how the mounted speaker will look once the installation is complete. To begin, mark four holes to indicate where you want to install the speaker bracket (Figure 4). For wood, drill four starter holes using a 3⁄32 inch (2,5 mm) drill bit (Figure 5). For cement, drill four starter holes using a 1⁄ 4 inch (6,0 mm) drill bit

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Maintaining Your 251TMSpeakers


ProblemWhat to do
Neither speaker plays• Check the settings on your receiver or amplifier. Refer to the owner’s guide that came with

it for instruction on settings.

• If your 251TM speakers are connected as a second set of speakers to your receiver or amplifier, check that the connections have been made to the “B” terminals and that the “B” speakers are selected to play.

The bass or treble is weak• Check the tonal balance setting on your receiver or amplifier.
Only one speaker plays




Only one speaker still plays

• Check the balance control on your receiver or amplifier and make sure it’s centered.

• Check the wires connected to the speaker that does not play. Make sure the wires are in good condition and are firmly connected. Review the “Making the connections” section on page 9.

• Disconnect the working speaker from the receiver or amplifier.

• Switch the cord of the “faulty” speaker from its original receiver or amplifier jacks to the

other set of jacks (the working speaker was originally attached to those jacks).

– If the speaker now works, the problem is in your receiver or amplifier. Reconnect your

speakers to a working unit.

– If there is still no sound from the speaker, continue below.

• Remove the cord from the working speaker and connect it to the “faulty” speaker.

– If the speaker now works, the problem was in the original speaker cord.

– If there is still no sound, the problem is in the speaker.

• If trouble persists, contact your authorized Bose® dealer, who will arrange for service. Or, contact Bose customer service. See the inside back cover of this owner’s guide for a list of phone numbers.

Warranty period

Bose 251 environmental speakers are covered by a limited five-year transferable warranty. Details of coverage are on the warranty card that came with your speakers. Please fill out the information section, detach, and mail it to Bose.

Customer service
For additional help in solving problems, contact Bose Customer Service. See the inside back cover for offices and phone numbers.

Cleaning your speakers
Use a cloth dampened in mild detergent and water to remove dust or dirt from the outside of your 251 speakers. Or use a hose to rinse them thoroughly with fresh water. Do not use enough pressure to force water behind the grille and into the drivers or the acoustic ports.

Protecting the speaker wire
The bare ends of the speaker cord can be affected by exposure to the elements. This is especially true of saltwater exposure. You may use a silicone caulking material, such as RTV adhesive, to protect the connections. It is commonly available at hardware stores. If you do use caulking, apply it only after the wires are connected and the knobs tightened down.Check the connections annually, and reapply as needed.

Technical Information

Protective features

  • Galvanized powder coated steel grille
  • Environmentally resistant hardware
  •  Polymer fiber composite drivers
  •  Nickel-plated brass connection terminals
  •  Syncom® computer quality control

Driver complement

  • Two (2) 21⁄ 2 ” environmental Twiddler TM drivers per speaker
  •  One (1) 51⁄ 4 ” environmental woofer per speaker


  • Dual-port molded polypropylene composite
  • Black or white


  • 131⁄2 ” H x 53⁄ 4 ” W x 8” D (34.29 cm x 14.6 cm x 20.32 cm)


  •  Compatible with amplifiers or receivers rated 10-200 watts per channel/rated 4 to 8 ohms
  •  100W IEC continuous power handling; rated 6 ohms

Environmental Capabilities

  • Designed to withstand:
    • salt fog, sun, high humidity (100%RH)
    • temperature extremes (-40°F to 158°F; -40°C to 70°C)

Wire recommendations

  • Based on a maximum frequency response deviation of ±0.5 dB
    Gauge                                             Length
    18 (0.75 mm2)                              30 ft (9 m) maximum
    16 (1.5 mm2)                                 45 ft (14 m) maximum
    14 (2.0 mm2)                                70 ft (21 m) maximum


  • 8 lb (3.63 kg) each


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