Bose Personalized Amplification System Troubleshooting Manual page 26

THEORY OF OPERATION
3. Cylindrical Radiator™ Loudspeaker L1
The L1 Cylindrical Radiator speaker array consists of two sections, an upper and lower section,
with 12 drivers each for a total of 24 drivers. The lower array section plugs directly into the cavity
in the center of the PS1 power stand. Electrical connections are made via Molex connectors in
the PS1 and the bottom of the lower array section. The upper section of the line array plugs
directly into the top of the bottom section, aligned by a bayonet pin. Electrical connection is
made by another Molex connector to the top of the lower array section. The result is that there
are no cables needed to connect the line array sections to the PS1 power stand.
There is no crossover or protection circuitry in either section of the line array. All protection and
EQ is performed in the PS1 power stand. The drivers of both sections are replaceable, as are
the grilles and the Bose ® logo.
4. Bass Module B1
The B1 bass module is a dedicated passive unit that houses two 5 1/4" drivers. The input is via
two 4-pole Neutrik ® Speakon ® connectors on the rear panel. Both of these inputs are paralleled,
allowing you to jumper multiple bass modules together. There are no crossover or protection
ciricuit components located on the input panel. All EQ and protection is performed in the PS1
power stand.
Pins 1+ and 1- of the input connector are used to apply the input signal to the bass module. Pins
2+ and 2- are connected to a 10k ohm resistor on the bass module rear panel PCB. This allows
the PS1 power stand to detect how many bass modules are connected to it from the Bass/Amp3
Out connector.
If the PS1 sees a 10k resistance, it knows that there is only one bass module connected and
adjusts the output level and EQ accordingly. If the PS1 sees 5k ohm resistance, it knows that
there are 2 bass modules connected, and again, adjusts the output level and EQ accordingly.
If the PS1 sees an infinite resistance, it knows that there is no bass module connected and
adjusts accordingly.
The woofers in the bass module are replaceable. The input panel, grille and Bose logo are also
replaceable.
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