Black Boxes: Jensen Matrix Wireless Audio Transmitter

by John Davis
Summer 2001

Jensen
(877) JENSEN-0
www.jensen.com
$99.95

Computers and the Internet are creating a revolution in music distribution. If only there were a way to get downloaded MP3s from the computer to the home stereo.
There is, Thanks to Jensen, the maker of the new Matrix Wireless Internet Audio Transmitter.

Out of the Box
Jensen's new Matrix Wireless Internet Audio Transmitter is a 900MHz transmitter and receiver pair, that allows you to transmit MP3s and streaming audio from your computer directly to your stereo. It consists of two small silver boxes, each with their own power cables.
When we opened the packaging, we found a transmitter, a receiver and two separate A/C adapters. We hooked the transmitter's stereo minijack into the line out on our test computer. Jensen included a "Y" adapter in case you want to connect the transmitter to the computer while the speakers, or headphones remain plugged in. We then connected the receiver into the stereo by locating an unused line-level input on our power amplifier (in our case, it was AUX3).

Setting Up
After we made our connections, it was necessary to regulate the volume level of the source (the computer) so that the transmitter had sufficient signal to broadcast to the receiver, without overpowering it. As indicated earlier, we used line-level audio ports to connect our audio equipment. Line-level signals all have the same "loudness." Most computers have a line out connector, but it is generally a "variable" line out, which means its "loudness" is adjustable, in this case by software.
The Matrix has an Audio Level Indicator light on the front that helped us set our computer's volume correctly. When the light was off, the signal was too weak. When the light came on and remained steady, the signal was too strong. When the light had a steady blink, it indicated that the volume was set correctly. The level control indicator light was not absolutely precise, but it worked well enough.

Tuning the Receiver
There is a light on the receiver, just like on the transmitter. The difference is that the one on the transmitter is an indicator of the strength of the audio signal, while the one on the receiver is a Tuning Indicator. Once we were broadcasting from our transmitter, we tuned the receiver until the Tuning Indicator light came on and stayed on. This indicated that the receiver was properly tuned to the same frequency as the transmitter. The sound went from silence to a monophonic sound, and then, finally, to a full, rich, stereo signal.

Other Uses for Matrix
Of course, you needn't connect the transmitter only to your computer. You could also connect a Walkman to your stereo. In fact, any audio source that is capable of generating a line-level signal can be a source for the transmitter. If the source you select does not use a stereo minijack to output line-level audio, then you will need an adapter.
It's also possible to connect Matrix in the opposite of the intended fashion. Most computer soundcards have a line-in connector, as well. You could hook the transmitter up to another source, perhaps your stereo, and hook the receiver up to the line-in jack on your computer. Then, listen to the radio, or cassette tapes, or whatever's at your desk, over your computer speakers. You would need adapters to accomplish this, but it is possible. Instead of cranking up your radio in the living room so that you can hear it at your desk in the den, use the Matrix!

Our take on Matrix
We found Jensen's wireless audio solution a very good idea. It was easy to set up, easy to use and helped to eliminate lots of wires. We found that it produced good quality audio, with minimal distortion at distances up to around 70 feet.
The audio we heard was very good, without any audible artifacts due to RF transmission. We occasionally heard interference from a nearby cordless telephone, although it was minimal. Where we tested it, there were three 900MHz cordless phones in use, as well as a plethora of other electronic devices, and it was rare that we got interference. Some cell phone services also use 900MHz, but we didn't hear any interference.
All in all, we found the Matrix to be a very handy gizmo. Anyone who wants to connect audio components at a distance will be pleased. Easy-to-use, with a fair price, Jensen has expanded their existing wireless product line with a smart accessory for delivering sound from the computer to the stereo.

Smart Specs
Transmitter: Omnidirectional
Effective transmitting range: up to 150'
Variable frequency adjustment: 912.5-914.5MHz
3.5mm (1/8") stereo minijack input AC adapter 12VDC, 100mA
Receiver: Frequency tuning control
S/N Ratio: 60dB
Channel separation: 30dB
Maximum distortion: <2%
Output: RCA stereo
AC adapter: 6VDC, 100MA