November 2, 2005
Zaxcom TRX-900 Digital Wireless Preview
by Nick Huston

Zaxcom has long been an innovator in the field recording industry from the first portable hard drive recorder to the first production digital wireless systems, and now the first digital recording transceiver. As these new wireless near their release date in early 2006, more and more buzz has been circulating and fortunately I got to see them first hand. Last week I spent a day with Glenn Sanders and the crew at Zaxcom poking and prodding the new wireless system to see just what all the fuss is about.

First, a little background on digital wireless systems: When originally conceived, digital wireless systems tended to be larger, more power hungry, and one channel occupied a significantly larger chunk of the RF spectrum, making it difficult to fit multiple units of wireless within the same frequency bandwidth as standard FM transmission wireless. Digital has come a long way since then. We were able to test a working prototype of the new Zaxcom TRX-900 to see what it could really do.

The first test we did was to put the wireless up on a scope to see just how it works. Because it is digital, the transmitter is sending a data stream of 1s and 0s to the receiver. This makes for a more secure signal as well as keeping the noise floor way down since the original analog mic signal is essentially reconstructed by the receiver from the digital information it receives, rather than transmitting and compressing/companding the analog signal itself. On a spectrum analyzer, a normal FM transmission wireless microphone looks like a jagged peak that changes size and shape as signal is passed through the wireless system. You also will see other similar, smaller peaks further down the RF spectrum. Digital wireless looks like a slightly wider, more rounded mountain that never changes. That one peak is the only peak that shows up on the RF spectrum. Given that a normal operating frequency block is 25 MHz wide, with clear channels it would be conceivably possible to fit more than 25 digital wireless systems in that block with no intermodulation. To test this theory, we took three wireless systems in the same block, set them to 3 different frequencies exactly .6 MHz apart. No hits, no zzzzt, just clean sound. At 600 KHz spacing, range and intermodualation were not an issue.

In addition to providing digital quality audio on a tight bandwidth with no intermodulation, Zaxcom’s new system brings a myriad of new features that make it truly unique. As I have mentioned before, the TRX-900 is a transceiver, meaning not only does it transmit, but it can receive as well. Receive what, you might ask, and for what purpose? Here are a few possibilities. Zaxcom’s new system can essentially be remote controlled by another unit, the IFB900. The IFB900 can be used to change frequencies, adjust audio levels, send an IFB signal for monitoring/prompting, start, stop, and send timecode to the TRX-900’s recorder. Monitoring and recording, you say? The TRX-900 has a headphone option which allows talent to monitor or be prompted by an outside source. Thus, if you were a news person and you were using the TRX-900, a producer could send a signal to the talent’s earbud to prompt them on changes and updates in the story, while the lavalier signal was transmitted back to your wireless receiver, keeping it clean and simple. The headphone option adds maybe a ¼” to the side of the transceiver. As for recording, the TRX-900 has an option that allows it to record 48 KHz 24 bit audio with timecode directly to a mini SD flash card. A 1GB card can hold almost 6 hours. The ultimate back up, this card can later be ejected, and its information downloaded into a computer where it can be sent to post production.  Using Zaxcom’s mini SD transfer station, you will be able to download up to six cards at the same time.

In addition to all of the technological achievements, the TRX-900 has undergone some huge mechanical innovations. The size of the transceiver is significantly smaller, measuring 2.3" x .69" x 2.1".  Zaxcom has also redesigned the battery door using a rugged and simple magnet-based system to keep the door closed. Using one 123a battery allows for quick and simple battery changes. The screen is also a totally new LCD screen, giving much more accurate and pleasant readouts than the old LED. The transceiver also was designed to be totally modular with 4 internal components that lock perfectly together to make the unit more rugged and serviceable. There are only 3 wired connections in the entire unit, two for the battery contacts and one for the antenna.

With greater demands being put on wireless microphones, Zaxcom’s new TRX-900 promises to meet and beat expectations opening up new possibilities for productions and for production sound mixers.

Gotham is currently accepting pre-orders for this new wireless system.  Click here to get on the list for the Zaxcom TRX900s.

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Published by Gotham Sound and Communications, Inc.
Copyright © 2005 Gotham Sound and Communications, Inc.. All rights reserved.
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