Introduction
The Audio Authority® Model 1805 is a compact amplifier designed to provide amplification for speakers in retail demonstrations. Volume may be controlled via RS-232 or RS-485 using custom control devices such as a touch screen or capacitive touch panel. Gain may be set per channel. For best results, use a commercial-grade media player such as the Model 1803 or MH2-HD MediaHub.
A compact, red audio amplifier unit, likely a MediaHub, shown from an angle.
A detailed diagram of the amplifier's front panel, illustrating the placement and labeling of all input/output jacks and indicator lights: POWER (12V DC), STATUS (ON), COM BUS (RS-485), RS-232 NULL, RS-232 STRAIGHT. It also shows the AUDIO INPUT (STEREO 3.5MM), LEFT SPEAKER (GAIN, TERMINAL, VOLUME), and RIGHT SPEAKER (GAIN, TERMINAL, VOLUME) connections.
Features
- Up to 10.5 watts per channel power output
- Volume may be controlled by RS-232 or RS-485
- Gain adjustment per channel
- Small footprint for easy placement in displays and fixtures
Audio Input
Connect a stereo analog audio source to the 3.5mm stereo Audio Input jack. If the source has volume control, raise the volume controls to the point of distortion, then adjust it down to the maximum level.
A close-up view of the 3.5mm stereo audio input jack on the amplifier.
Connectivity and Indicators
RS-232 Ports
The RS-232 ports receive and pass-thru communications to other serial devices at 9600 Baud rate. A variety of RJ-45 serial cable adapters are available from Audio Authority. Serial commands include: Volume Up [VOL+] and Volume Down [VOL-]. For volume control, commands range from [VOL=0] (Min) to [VOL=128] (Max).
RS-485 Bus
The RS-485 communication pathway is for use with custom applications such as TouchSelect control panels and BrightSign® media players.
A view of the amplifier's rear panel showing four RJ-45 connectors labeled "RS-232 STRAIGHT", "RS-232 NULL", "RS-485 BUS", and "RS-485 BUS".
Power Input
Connect the 12V power supply (included) to the jack marked Power Input.
Indicators
The green Power LED provides visual indication of the amplifier's on/off state. The yellow Status LED indicates when the input is over-driven or when the speaker outputs have a short.
A close-up view of the amplifier's front panel indicator lights, highlighting the GREEN POWER LED and YELLOW STATUS LED.
How to Set the Model 1805 Amplifier Gain Controls
- Raise the source volume controls (if present) to maximum.
- Turn the 1805 gain dials (left and right channels) to 1 and start the audio source playing.
- Select a speaker position, and raise the 1805 gain dials to the point of distortion, then reduce to the desired maximum level. Check all of the connected speakers for distortion, readjust 1805 gain levels if necessary.
A close-up view of the two rotary gain control dials on the front panel, labeled "LEFT CHANNEL GAIN" and "RIGHT CHANNEL GAIN", with numerical markings from 1 to 8.
Power Specifications
Measurements with an 8 ohm load, both channels driven:
| 12V | THD | Watts per channel |
|---|---|---|
| Power Supply PN:571-043 | 1% | 8.5 |
| 10% | 10.5 |
Frequency response at 8.5W per channel: +/- 1.452 dB 20Hz-20kHz.
Installation
- Attach the amplifier to a flat surface with the screws provided.
- Allow adequate ventilation for the amplifier.
- Connect speaker terminals securely.
- Connect the 3.5mm stereo cable from the source.
- Connect the power supply to AC power, then to the power port.
- Adjust gain (see page 3).
- Call Audio Authority with questions that are not addressed in this manual.
Example System
The Model 1805 sends amplified audio to the Model 1819 switch modules that route audio to the speakers. The Model 1803 media player's MicroSD card contains the uncompressed audio content and provides the low-level input signal for the Model 1805 amplifier. The TS09 controls the demonstration system via RS-485.
A block diagram illustrating an example system setup. A "TS09 TOUCH PANEL" is shown controlling a "Model 1803" media player. The "Model 1803" outputs a signal to the "Model 1805 Variable Gain Amplifier". The "Model 1805" then sends amplified audio to "Model 1819" switch modules, which distribute audio to multiple "SPEAKERS". Connections are color-coded and labeled: "RS-485 CONTROL" (blue), "SPEAKER BUS" (green), and "SPEAKER WIRE" (black).
