Bose AM-30P Service Manual - Page 6

Browse online or download pdf Service Manual for Speakers Bose AM-30P. Bose AM-30P 49 pages.

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1. Overview

The AM-30P is a five channel, 175 Watt, surround-sound powered Acoustimass

designed to be used with either the CD-20 or CD-5V Music Center. The AM-30P and CD-20

together form the complete Bose

the AM-30P include:

• Patented Acoustimass speaker technology

• Five independent high efficiency Class-G power amplifier channels

• Patented (VideoStage

• Microcontroller based remote control operation

• Patented low frequency dynamic equalization

• Miniature Jewel Cube

• Manually adjustable bass and treble tone controls

The bass module portion of the AM-30P is identical to the AM-25P and similar to the AM-5 II

Acoustimass loudspeaker, except that the woofers are 8Ω instead of 4Ω, wired in parallel and

driven as a single channel. The acoustic response has been modified for powered speaker

application. The Jewel Cube satellite speakers have been specially designed to work exclu-

sively in equalized powered speaker applications .

The following theory of operation relates to the electronic module. The electronic module

consists of two printed circuit boards (referred to as the "Main" and "Amplifier" PCB) and a

magnetically shielded power transformer. Each PCB will be discussed separately. First, a

general operation and block diagram overview will be given (See Figure 8 block diagram),

followed by a detailed description of each diagram block that will reference the schematic

diagram.

2. GENERAL OPERATION AND BLOCK DIAGRAM OVERVIEW

Connection to the CD-20 occurs through a 30 ft. shielded audio cable that carries the following

signals:

• Left and right stereo audio (shielded)

• Turn-on signal (10VDC)

• Serial data signal

Figures 1, 2, and 3 show the total system frequency response, from DIN input to speaker

output, for the left, right, center, surround, and bass channels.

2.1 General Audio Chain (Refer to Figure 8 PCB Block Diagram)

Audio is buffered and amplified by the DIFF-AMP stage and then passed through a preliminary

equalizer stage COMMON-EQ. Next, the audio is passed through a volume control dependent

dynamic equalizer stage (consisting of the blocks labeled 37HZ BPF and DYNAMIC EQ VOL)

and then presented to the digitally controlled master volume control stage. This is followed by

an analog treble control stage (manually adjustable potentiometer). Next, the surround sound

decoder splits the left and right channel audio into five components: left, right, center, sur-

round, and bass. Within the decoder block, center and surround channels pass through sepa-

rate digital volume controls. The bass channel output is fed to an adjustable level control. Each

of these channels pass through separate equalizer stages, and then exit the Main PCB to the

power Amplifier PCB where they are amplified and sent to each speaker.

THEORY OF OPERATION

Lifestyle

30 home theater audio system. Major features of

) surround-sound decoder

satellite speakers

loudspeaker,