How to Install the Model 1643 Amplifier

Introduction

The Model 1643 amplifier delivers 15 watts per channel of clean power, suitable for driving speakers in retail demonstration environments. It features an automatic gain reset function, adjusting the amplifier's gain to a selectable default level after a period of inactivity or upon receiving a specific deselect code from a distributed switching system. Integrated UP and DOWN buttons allow users to control volume levels within predefined limits. Multiple amplifiers can be linked together, with a master unit managing the volume control for several slave units.

Connecting the 1643 to the Display System

Follow these steps to connect the Model 1643 amplifier:

1. Connect the DC POWER terminal block to a 13.8-volt power bus capable of supplying at least 5 amps.
2. Connect the speaker terminal block to the speaker bus.
3. Connect the SYSTEM BUS header to the Access™ System Bus. Note: The switching system can be powered from this port, but the amplifier itself must be powered through its dedicated DC POWER INPUT port.
4. Connect the VOLUME UP/DOWN headers to external up/down pushbutton switches.
5. Connect the input jacks to the input signal bus.

Front Panel Description

The front panel features controls and indicators for:

• VOLUME rotary switch with MIN (minimum), DEF (default), and MAX (maximum) settings.
• TIME OUT rotary switch to set the delay before volume reverts to default.
• BUS OUT connector (used for system bus connection when ganging units).
• INPUT jacks for left (L) and right (R) audio signals.
• NORMAL/SLAVE switch to select master or slave mode.

Back Panel Description

The back panel includes:

• Speaker terminal blocks for left (L) and right (R) outputs.
• SYSTEM BUS header for connection to the switching system.
• VOLUME UP/DOWN headers for external pushbutton switches.
• DC POWER INPUT terminal block (13.8 Volts, 5 Amps Max, internally fused).

Setting Up the 1643 Controls

Configure the controls on the Model 1643 as follows:

1. Set the NORMAL/SLAVE switch to the NORMAL position for a single amplifier setup. (Do not use the BUS OUT jacks in this configuration).
2. Set the MAX switch to determine the maximum volume limit (0 for lowest, 9 for highest).
3. Set the DEF switch to determine the default volume level (0 for lowest, 9 for highest).
4. Set the MIN switch to determine the minimum volume limit (0 for lowest, 9 for highest).
5. Set the TIMEOUT switch to specify the delay period before the volume reverts to the default position. Refer to the Timeout Example Chart for guidance.

Timeout Example Chart

This chart helps calculate the time it takes for the volume to return to the default setting after the last activity in the switching system.

Ganging or Bussing Multiple 1643 Modules Together

To connect multiple Model 1643 amplifiers in a chain:

1. Configure the first module in the chain as described above, connecting its power supply and volume buttons.
2. Set the rotary switches (MIN, DEF, MAX, TIMEOUT) on all subsequent modules in the chain to zero (0).
3. Set the first (master) 1643 module to NORMAL mode, and all other (slave) modules to SLAVE mode.
4. Connect all amplifiers together to ensure they receive the same low-level input signal.

Ganging Diagram Description

The system diagram illustrates the following connections for ganging multiple amplifiers:

• The SYSTEM BUS header on each amplifier connects to the main switching system.
• External VOLUME UP and VOLUME DOWN pushbutton switches connect to the respective headers on the amplifiers.
• The AUDIO SOURCE connects to the INPUT jacks of the first (master) 1643 amplifier.
• The OUTPUT terminal block of each amplifier connects to the INPUT jacks of the subsequent amplifier in the chain, forming a daisy-chain.
• The DC POWER SUPPLY connects to the DC POWER INPUT terminal block of each amplifier.
• Each amplifier's SPEAKER OUTPUT terminal block connects to its designated speaker.