Bose 301 Series III User Manual download pdf (Page 6)

5

TEST PROCEDURES

Note: Before performing any tests, remove both

grilles by following the grille removal instructions in

the disassembly section of this manual.

1. Woofer Rub and Tick Test: Connect the

output of a signal generator to the input of a

power amplifier. Connect the output of the

power amplifier to the input terminals of the

speaker under test, (see Figure 1). Adjust the

frequency of the generator to 45 Hz and the

amplifier output to 8 Vrms. No extraneous

noises such as rubbing, scraping or ticking

should be heard.

Note: To distinguish between normal suspen-

sion noise and rubs or ticks, slightly displace

the cone of the woofer with your fingers. If the

noise can be made to go away or get worse, it

is a rub or tick and the woofer should be re-

placed. If the noise stays the same, it is normal

suspension noise and the woofer is fine. Sus-

pension noises will not be heard with program

material.

2. Woofer Sweep Test: Sweep the signal genera-

tor from 10 Hz to 5 kHz using the 8 Vrms signal.

There should be no loud extraneous sounds. If

there are any loud buzzes or distortion, replace

the woofer.

Test Connections, 301

®

Series IV Speaker

FIGURE 1

+ -

Audio Signal

Generator

Power Amplifier

Input Output

Back of Speaker

Under Test

- -

++

RIGHT

Red ( + )

Black ( - )

Note: There should not be any buzzes or

rattles from within the speaker cabinet. Re-

dress any wire or component that buzzes.

3. Tweeter Sweep Test: Reduce the amplifier

output to 3 Vrms and continue sweeping from 5

kHz to 15 kHz. Replace either of the tweeters

in which buzzing or distortion occurs.

4. Air Leak Test: Using an 8 Vrms signal, set the

generator frequency to 45 Hz. Listen for air

leaks around the woofer, tweeters and cabinet

seams (glue joints). Any air leaks will be heard

as a sputtering or hissing sound. The repair of

air leaks can be made by repositioning the

transducer gaskets.

5. Woofer Phase Test:

Note: In this test, supply voltage should only

be momentarily applied to the speaker input

terminals to avoid possible damage to the

speaker.

Set a DC power supply to 8 volts. To ensure

that the woofer 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 woofer

should move outwards with the application of

the supply voltage.

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