Bose 251TM - Environmental Speakers Manual

Selecting the location for your Unit

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 251 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.

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.

Speaker placement guidelines

Installing Your Device

Choosing the unit 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". 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.

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 251 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.

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".

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 below illustrates how the mounted speaker will look once the installation is complete.

251 environmental speaker mounted onto the exterior of a house

To begin, mark four holes to indicate where you want to install the speaker bracket.

For wood, drill four starter holes using a ³⁄₃₂ inch (2,5 mm) drill bit. For cement, drill four starter holes using a ¹/₄ inch (6,0 mm) drill bit.

For mounting onto wood, install the supplied screws using a Phillips-head screwdriver (A). For concrete use, first install the supplied plastic inserts. Then, using a Phillips-head screwdriver, install the screws (B).

Installing the hardware

1. Wood
2. Concrete

Installing the brackets onto a deck railing or table
The 251 speakers should be mounted in a vertical position to achieve the best musical performance. Figure below illustrates how the mounted speaker will look once the installation is complete.

251 environmental speaker mounted onto a deck railing or table

To begin, mark four holes to indicate where you want to install the speaker bracket.

Then, drill four starter holes using a ³⁄₃₂ inch (2,5 mm) drill bit.

Finally, install the four screws using a Phillips-head screwdriver.

Installing the bracket onto a deck railing or table

Note: If you are mounting your 251 TM speakers on a deck railing or table, you will need to rotate the Bose logo. Refer to "Rotating the Bose logo" for instructions on how to do this.

Attaching the unit to the brackets

Once the brackets are installed, carefully follow these steps to attach the speakers to the brackets. First, insert the knobs into each side of the speakers. Be sure to turn each knob two full rotations.

Installing the knobs

Then, carefully slide the speakers into the brackets.

Finally, temporarily tighten the speaker in a position that will allow you to easily connect the speaker wire.

1. Exterior of the house
2. Deck railing or table

Making the connections

Preparing the speaker wire (not provided)
Speaker cord consists of two insulated wires. The insulation around one wire is striped, collared, or ribbed. This marked wire is positive (+). The plain wire is negative (–). These correspond to the red (+) and black (–) terminals on the back of the speaker, receiver, or amplifier. Be sure to connect each wire to the proper terminal (positive to positive, negative to negative).

At the ends of each cord, strip approximately ¹⁄2 inch (1.3 cm) of insulation from both wires. Next, twist the ends of each wire so there are no loose strands.

Connecting the speaker wire to the speakers
At the back of your speaker, unscrew the hex knobs on the terminal posts. This reveals a small opening through each post.

Using the wire guides, insert the marked wire into the red (+) terminal. Then insert the plain wire into the black (–) terminal. Tighten the knobs to secure the wires.

1. Exterior of a house
2. Deck railing or table

Connecting the speaker wire to the receiver or amplifier

1. Connect the speakers on the left side of the listening area to the left channel of your receiver or amplifier.
   
   1. Attach the marked wire to the red (+) terminal.
   2. Attach the plain wire to the black (–) terminal.
2. Connect the speaker on the right side of the listening area to the right channel of your receiver or amplifier, following the same procedure above.

Note: If your 251 speakers are being connected as a secondary set of speakers to your receiver or amplifier, be sure to make the appropriate connections to the "B" channel.

Checking the connections
Check the speaker connections carefully. Make sure no loose strands of wire touch across terminals. This could create short circuits that can damage an amplifier or receiver. Tighten any loose connections before you plug in the receiver or amplifier.

Testing the connections
To make sure your speakers operate correctly, follow these steps:

1. Set the balance control on your receiver or amplifier to normal (centered).
2. Play some deep bass passages of music through the speakers.

The sound should seem to come from a point between the two speakers. The bass should be full and natural. If not, your connections may be reversed, causing the speakers to play out of phase. Refer to "Making the connections". To correct the problem, make sure all the wires are connected positive to positive (+ to +) and negative to negative (– to –). Then repeat steps 1 and 2 to re-test the speakers.

Putting the speakers in the final location
Loosen the knobs on each speaker to rotate the speakers into the desired position. Then, tighten the knobs to secure the speaker in its final position.

1. Exterior of the house
2. Deck railing or table

Attaching the rubber feet
If you do not plan to use the supplied brackets to mount your 251 environmental speakers, you can place them on a sturdy, level surface. They should be standing in the vertical position. Be sure to attach the rubber feet before using your speakers. For proper balance be sure to place the feet in the position shown in Figure below.

Rotating the Bose logo
Mounting the speakers on a deck railing or table will require you to rotate the Bose logo. Using your fingers, gently lift the logo, taking care not to detach it from the speaker, about ¹⁄4 inch (.24 cm) and turn it 180º.

Troubleshooting

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.

Maintaining Your Device

Cleaning your device

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 unit 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 drivers per speaker
• One (1) 5¹⁄4" environmental woofer per speaker

Enclosure

• Dual-port molded polypropylene composite
• Black or white

Dimensions

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

Compatibility

• 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

Weight

• 8 lb (3.63 kg) each

© 2008 Bose Corporation, The Mountain
Framingham, MA 01701-9168 USA

Documents / Resources

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