Bose 151, 111 Service Manual

Model 151™ and 111™ ENVIRONMENTAL SPEAKER SYSTEM

Transducer: Cabinet:

1-4.5" (11.4 cm) full-range, Black or white high-impact molded
environmental driver polypropylene

Nominal Impedance: Speaker Dimensions:

4 Ohms 6.1"H x 9.1"W x 5.9" D

IEC Power Rating: Shipping Weight

Min: 10 Watts Per Channel 4.0 lbs. (1.8 kg) Per Speaker
Max: 40 Watts Per Channel

©

200 Bose Corporation

SPECIFICATIONS

(15.4 H x 23.0 W x 15.0 D cm)

Service Manual

Test Procedures

NOTES: In each test procedure, it is necessary to remove the grille to access the driver.

Refer to the Grille Removal procedure.
Polarities are not marked on the input terminals of the 151™ speaker. The red terminal is

the positive (+) terminal and the black terminal is the negative (-) terminal. See Figure 1.

1. Rub and Tick Test
A. Connect a sine wave oscillator to a power amplifier. Adjust the frequency of the oscillator

to 10 Hz and the amplifier output to 6 Vrms. Connect the amplifier output to the input
terminals of the 151 speaker (see Figure 1). No extraneous noises such as rubbing,
scraping or ticking should be heard.

NOTE: To distinguish between normal suspension noise and rubs or ticks, displace the
cone on the driver slightly with your fingers. If the noise can be made to go away or get
worse, it is a rub or a tick and the driver should be replaced. If the noise stays the same, it
is normal suspension noise and the driver is fine. Suspension noises will not be heard with
program material.

2. Sweep Test
A. Sweep the oscillator from 10 Hz to 3 kHz using the 6 Vrms signal. There should not be

any loud extraneous sounds. (Note: A "whooshing" noise from the port at approximately 80
Hz is acceptable). If there are any loud buzzes or distortion, replace the driver. (See
Disassembly/Assembly Procedures for instructions on replacing the driver).

NOTE: There should not be any buzzes or rattles from within the speaker cabinet. Redress

any wire or component that buzzes.
B. Reduce the amplifier output to 3 Vrms and continue sweeping from 3 kHz to 15 kHz. If

there is any buzzing or distorting,replace the driver (see Disassembly/Assembly
Procedures for instructions on replacing the driver).

1

Audio Signal
Generator

Power Amplifier

Input Output

--

+

-

++

Speaker

-

+

Red (+)
Black (-)

Figure 1. Test Connections 151™ Speaker

3. Air Leak Test
A. Using the 6 Vrms signal,set the oscillator frequency to 10 Hz. Block the ports. For at

least 3 seconds, listen for air leaks around the driver and baffle. If there is a "whooshing"
noise around the driver, re-position the driver gasket behind the driver to make an airtight
seal. If there are similar noises around the baffle, make sure that it is securely fastened to
the speaker cabinet.

4. Phase Test
NOTE: Supply voltage should only be momentarily applied to the speaker input terminals to

avoid possible damage to the speaker.
A. Set a DC power supply to 10 volts. To ensure that the driver is connected in phase,

connect the positive lead of the supply to the positive (+) speaker input terminal and the
negative lead to the negative (-) input terminal. The driver should move outwards with the
application of the supply voltage.

2