Bose LIFESTYLE SA-2 Theory Of Operation

General Information:

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The Lifestyle SA-2 or SA-3 stereo amplifier provides you with a simple solution when you want to add Bose
non-powered environmental speakers or Bose non-powered accessory speakers to your Lifestyle
Bose proprietary Integrated Signal Processing technology, featured in the amplifier, provides full, rich stereo
sound, even when the speakers are playing at low volumes. By using the Lifestyle
your system, you can enjoy Bose quality sound and Lifestyle
swimming deck, garage, or utility room.
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The Bose Lifestyle SA-2 and SA-3 amplifiers are a zone 2 accessory to the Bose Lifestyle
repair package for installation instructions) and Bose
require an additional RF remote control in order to operate the second zone. This is because the dip switches
located in the remote control must be set differently to control zone 2 (see repair package for settings).
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Lifestyle systems that use a PMC/MRI (such as the Lifestyle
control.
Note: The circuit operation described below is for the left channel. The right channel operation is identical. The
designators inside the brackets are schematic sheet grid locations.
Refer to schematic for the following information.
The rear panel of the Lifestyle
DIN. These jacks, along with an audio input cable, part number 272902-220 supplied with the
amplifier, allow the use of the different Lifestyle
installation, see the repair package for the installation to the system you are working with.
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Bose link is the proprietary networking technology that allows a Lifestyle
products to provide sound in secondary rooms.

Introduction:

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The Lifestyle Stereo Amplifier 2 and the higher power Lifestyle
printed circuit board. The LSA-2 is a depopulated version of the SA-3. The differences between the two
products can be summarized as follows:
Feature
Power output
Amplifier topology
Auxiliary RCA input
Mono/Stereo switch

General Theory of Operation:

Refer to the system block diagram (Figure 1).

Audio Chain:

Audio Input is received at the DIN connector in the form of two separate analog stereo (left and right) channels
(channel 1 and channel 2) from the music center. The LSA-3 has a third audio input, via the left and right RCA
jacks. Channel selection, volume level, and dynamic equalization occur at the volume control IC U3 (the ST
TDA7309). Output from this IC is fed to a differential pre-amplifier stage, and then to the power amplifier IC.
11/22/2005
SA-2 and SA-3 Theory of Operation
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amplifier utilizes two different types of audio input jacks, RCA and
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music centers. Different Lifestyle
LSA-2
40W/ch
Class AB
No
No
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system convenience in your yard, patio,
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speakers. Lifestyle Systems that use a music center
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40 and 50) do not require an additional remote
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system to integrate with other Bose
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Stereo Amplifier 3 product use the same
LSA-3
100 W/ch
Class G
Yes
Yes
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system.
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stereo amplifier to expand
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systems (see
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systems require different
27172X-00
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