For years the New York Clear Channel stations transmitting from the Empire State Building used BDI 3×2 composite switches to change STL feeds as necessary. With HD Radio, then PPM and finally our studio consolidation, we decided it was time to upgrade the capability of our STL switches so that several new requirements could be met: We now feed programming to our analog and HD Radio transmitters; Arbitron was pressing us to match PPM sources between analog and our primary (simulcast) digital; and we also wanted automated "smart" switching between three different sources.

I made up a block diagram of a switcher that would do what we needed. New York Director of Engineering Josh Hadden suggested I talk to Bob Tarsio of BDI to see if the company would build this new device for us. We needed five of them. I ran it past Tarsio and his team, and they proposed a semi-custom version of the ATB-300 Audio Toolbox, which became the DAB-300.

At its most basic, the DAB-300 is an automated AES3 switcher that will choose one of four AES3 inputs, and route it to all four AES3 outputs, based on basic configuration parameters. All inputs and outputs are 110ohm AES3. The unit occupies 1RU and is 10.25" deep. As you can imagine, rear apron space is limited, so the inputs and outputs are brought out to a breakout panel, which itself is 1RU. The remote controls are accessed via DB-25 connectors on the rear of the DAB-300.

When used in manual mode, the unit operates like any other switcher. Select the input on the front panel and press the take button. Beyond that, there are options to modify the signals that come in to and go out of it. Looking at each individual input, the following options are available: