To identify the unit's variation, check the part number and description on the left and right input terminal panels. The Jewel Cube versions of the Acoustimass and video variations will state "Jewel" on the terminal panels, i.e. BUILT-INvisible Jewel Home Theater. If it doesn't state that it is a Jewel Cube version on the terminal panel, then it is the non-Jewel Cube, or Acoustimass-5 cube speaker version.

Audio Variations:
Acoustimass (Jewel Cube and non-Jewel Cube): 175461-01
Three Room System: 175461-02
102EA-II: 175461-03

The Bose® BUILT-INvisible® 102EA II, 3 Room and Acoustimass® Amplifiers are completely self-contained systems. They include all of the circuitry required to accept line-level audio sources, to process signals as a two channel/two room system, and to power a variety of Bose installed loudspeakers through some or all of the six power amplifiers contained in the systems. These are audio only systems, and do not process video surround information. There are two video versions of the BUILT-INvisible amplifier that include a Videostage® decoder capable of processing video surround information and driving the appropriate Bose loudspeakers for home theater use.

The BUILT-INvisible 102EA II, 3 Room and Acoustimass systems have three stereo inputs, each with differential input circuitry to permit long cable runs through the home while maintaining excellent noise immunity. The inputs accept signals from Bose Lifestyle® Music Centers as well as conventional audio sources. The three stereo inputs connect to an automatic input switcher. This switcher enables the amplifiers to function as three source/two zone systems when used with multiple source components. You can tailor the operation of the automatic input switching to each customer's wishes by means of two preset terminals which allow the installer to determine how the amplifier will behave when presented with multiple sources. Rooms can be configured to switch to a new source when it plays, or remain dedicated to a single source. A single source can play in both rooms, or room 1 can play one source while room 2 plays a second source.
 When you install a system with the Bose CD-20 Music Center, the input switching circuitry should be defeated using the preset terminals located on the amplifier chassis. This allows full control of source selection from the CD-20 remote control.

BUILT-INvisible Audio Systems at Turn-on
The system will come up in standby by default when AC mains power is applied to it as long as none of the turn-on signals listed below are applied. When the system is in standby, the following conditions are in effect:
- The power amplifiers are off
- The DC voltages at the -8 Vdc and +8 Vdc terminals are active
- The Remote Turn-on terminals are enabled
- The Presets are enabled
- The audio signal inputs are enabled
- The automatic input switching circuitry is enabled

When the system is in standby, it is waiting to sense an audio signal at one of its audio input terminals or a remote turn-on signal at one of its remote turn-on terminals. This is the state of operation that the system is normally in as installed when not in use. Once a turn-on signal or an audio signal is applied to the appropriate terminal, then the system will switch into the correct mode of operation as determined by which terminal the input is applied to and how the presets are configured. When the system is in operation, the power amplifiers are enabled, and the system will produce audio at the correct locations.

The Bose® BUILT-INvisible® home theater is a completely self contained system. It contains all circuitry required to accept line level audio sources, to process signals as a two channel, three speaker music system or as a four channel, six speaker home theater, and to power a variety of Bose installed loudspeakers.

The system incorporates Bose patented Videostage surround processing circuitry. It is fully compatible with Dolby Surround, Dolby Stereo and UltraStereo. Videostage steering logic was specifically designed for the unique acoustical characteristics of a home environment. Proprietary Bose processing also allows adjustment of the width of the center channel for any screen size. This is not simply the volume of the center channel, but the spatial extent of it as well. You can create many different types of home theater systems using this one chassis. Operating the various systems depends on which terminals you use, which signals you connect, and how you connect them.

The Bose® BUILT-INvisible® home theater system is an audio system by default. It will play audio until you tell it to operate as a home theater. For example, if a CD changer is providing audio throughout the home and you connected its signal to terminals 17 and 18, the system will operate in audio mode. If any one of the three home theater mode turn-on signals listed above becomes active, the system will switch to home theater mode. When the system is in home theater mode: - The Left and Right Audio Inputs at blocks 17 and 18 are deselected.

- The Left and Right Audio for Video Inputs at blocks 6 and 7 are selected.
- The Videostage® surround processor is enabled.
- The chassis reads the voltage present at the Home Theater VCA Input terminal at block 2 to set the volume level. The surround encoded stereo audio signal connected to the audio for video inputs will decode into left, right, center and surround signals. The signals are routed as follows: