Performance: The AD903 allows the connection of almost any other audio device, input or output, to a cabled intercom system. Typical applications include: 1) feeding the signal from a stage microphone or audio mixer output into the inter- com system so that intercom users can monitor the program from a distant point; 2) feeding the intercom conversations out to an audio amplifier, and; 3) connecting the intercom system to another intercom system which is operating on a dif- ferent voltage or standard.
The AD903 is connected into the intercom system as is a belt pack, via the 3-pin female XLR on the rear. A 3-pin male XLR is provided for looping onwards to the next station in the system. The AD903 is powered by the intercom power sup- ply. Input and output are accessed via the 4-pin male XLR, also on the rear panel. Front panel high/low switches and 15-turn potentiometers allow the user to level-match virtually any input or output, from microphone level to line level. A third potentiometer is used to null the sidetone effect, reducing cross-talk.
The input stage of the AD903 includes a studio-quality microphone transformer. The output is also transformer isolated. Frequency response has be carefully shaped to optimize both intelligibility and long-term listening comfort.
Durability: The ribbed, extruded aluminum case; polypropylene end bezels; internal support system for the PC board; carefully mounted components; best-quality XLR-type connectors, and; recessed controls, all contribute to the outstand- ing ability of the AD903 to withstand rough usage.
Value: The comparatively low price of the AD903 is made possible by the minimized assembly cost, resulting from sim- plicity of construction. Simple construction also affords the use of higher quality components, and increases the ease (thus lowering the cost) of servicing.