WNYC in New York City's large newsroom. Photo courtesy of The Systems Group.

During the planning phase for construction of a radio station experience will come in to play, along with desires to do something new. Sometimes when confronting design problems it is helpful to have access to other engineers' approaches to the same or similar problems. This could go on for page after page, but I've picked some good recent examples: an easy way to get access to dozens (or hundreds) of audio sources from your networked PC; a means to mitigate lightning damage in the worst of circumstances; a way to handle the selection and distribution of mix-minus feeds for multiple radio stations all under the same roof; and finally a convenient way to solve the age-old problem of off-air reception at the new place. Take a look. I think you'll find all of them to be interesting.

Multiple monitors

In the “old” days, one feature of a radio station technical facility was a means by which audio from multiple sources could be sampled at multiple locations. There are many examples of how this was done: The most modern and effective means up to this point was having a routing switcher, and having a router head at each of the locations.

This is somewhat of an expensive proposition. Some routers could alternatively be accessed via a virtual control panel that would be live on a computer workstation, but even this required the use of a router output; so the proposition was still quite expensive.

Before that, likely the station had an array of pushbutton panels; a good example of that would have been the PR&E LS-10. However, if you were building a newsroom for a well-staffed news radio station, you could have a dozen or more switch arrays such as this. Installation of such a system would have been time-consuming, and therefore very expensive. Dedicated pairs of wires needed to be installed and were used (however frequently or infrequently) for this purpose alone.

Going back even farther than that, you would often see homebrewed switch panels, all made by someone in the engineering department, installed at each location. My favorite version of this was the rotary switch/Op-amp Labs/4-inch speaker built into a bathtub chassis. Of course it worked great until the rotary switch got noisy. Then someone had a big soldering job ahead.

So fast-forward back to the present. If you were building a new studio facility, what would be the best way to handle this requirement? Could there be a streaming audio approach? One that would make use of the computers you already have at each workstation, along with the network wiring already installed? A method that would effectively add nothing to the wiring costs? Of course there is: the Audio TX Multiplex.

Audio TX Multiplex

Multiplex is a system that consists of the audio server with associated software, along with client software (called Audio TX Multiplex Receiver) for each of the workstations in use by those who need access to multiple audio sources. One server can give access to as many as 96 audio sources for the system; an additional server(s) can be added to handle more audio sources. The server accomplishes IP multicast so that multiple users (over a LAN or WAN) can access the streams simultaneously. The system is licensed based on the number of audio sources that make up the system. Each of the source channels can be configured for different levels of quality; for example, 20Hz to 20kHz audio bandwidth, uncompressed, with a 48kHz sample rate would represent the high end of the quality scale. The user can also select lower sample rates, mono as opposed to stereo, and data compression schemes such as MP3 and MP2 with mono data rates down to 64kb/s.