Dan Braverman of Radio Systems was with us to present his Studio Hub hardware. As an introduction, he mentioned that Radio Systems got into the business by building AM carrier current transmitters. They are still sold, and when you see the "tune to 530 for information" signs along the road, chances are, they are using a Radio Systems transmitter.

In the 1980s, Radio Systems was big into building studios. They had crews of engineers and wiremen, and would send them out for weeks on end to build studios from scratch. That business tapered off, but has made a resurgence with the recent consolidations. Dan found himself out to get an installation started, and became intrigued by the way network wiring seemed to go in like a snap with one installer, while his crew spent weeks of soldering, etc.

Out of that experience grew the "Studio Hub" line of wiring accessories, which takes standard Category 5 wiring, and adapts it to the needs of transporting AES/EBU as well as audio or control.

One of the first questions that engineers come up with is the impedance of the wiring. The AES standard is 110 Ohm for twisted pair, and Category 5 wire is 100 Ohms. A look at the AES standard reveals that the tolerance is fairly wide – on the order of 20%, which easily allows 100 Ohm wiring. The BBC apparently even wrote a white paper some time ago about wiring a digital audio plant, and they concluded that Category 5 wire gave the best bang for the buck.

Not too far behind the question of impedance, is the question of shielding. In fact, Category 5 wiring is so well balanced, and the twist so well controlled, that shielding is relatively unnecessary. However, Dan has come up with a line of wire that he has had custom made in various lengths and bundles (for trunk cables) which shields each set of 4 pair from the others. Dan had Comcast build a custom trunk cable using 8 shielded category 5 cables. The tested crosstalk from pair to pair in a given 4 pair is greater than 100 dB.

The standard termination is the 110 block. Radio Systems has developed a very thorough lineup of accessories with XLR breakouts, D-Connectors, etc. A number of interface boxes has also been developed which speed the process of installation. Things like headphone amps, balance amps, A/D, D/A, microphone preamps, and others on the drawing board. The active devices are powered using a wire pair that is not used by any known network card or device. In fact, many network cards do not even have contacts for more than two pair.

Among the larger interfaces developed are the SAS router connector/adapter, and the patch panel. He was able to build a connector assembly that practically makes the SAS router plug and play. The patch panel uses RJ-45 connectors, and switches to enable or disable normals. The rear of the panel also uses RJ-45 connectors.