Hardware Review for Nefsis / Review of Phoenix Audio Duet
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4/1/2009 9:03:16 PM / Edited 4/4/2009 1:26:04 AM by Colin

Nefsis – Hardware Review

April 1st, 2009

Phoenix Audio Duet


Are you experiencing frustrating echo feedback during your video conferences? The echo, sometimes referred to as ‘feedback’ or ‘acoustic echo’, can be disruptive to say the least. One solution is to use an echo cancelling speaker-microphone combo like the Phoenix Audio Duet. Designed to stop the echo effect, the Duet raises the quality of hands-free conferences. The Duet is easy to install and for under $200, is an affordable solution.


The Duet is a tabletop speaker-microphone device and connects to your PC through a USB connector. Once connected, the Duet presents itself as a sound device similar to a sound card. Just set the Duet as your default microphone and speakers and it will eliminate the echo effect in your online meetings.

The Duets uses a DSP (digital signal processor) to run an efficient echo cancellation algorithm. The unit comes in two models; the Executive and the PCS. The Executive covers larger rooms by daisy chaining multiple units while the PCS works as a standalone unit.

The overall form factor is sleek and portable. The unit measures at 3.75 x 4.5 inches wide and 1.25 inches thick. Similar to other table top units, the speaker faces the top with the volume and mute controls located on the top edge.


Installing the Duet was simple. All I had to do was connect the Duet’s USB cable to my PC and Windows did the rest. No custom drivers needed! Windows listed the Duet as a PhnxMT202 device. (Windows may identify Duets with older firmware as the AK4571, while models with newer firmware are listed as PhnxMT202t).

Within seconds of connecting the Duet to my lab PC, I noticed a bright blue glow around the volume controls. The LEDs give the Duet a professional look and feel and are a nice touch.

After installing the drivers, I followed a couple of recommendations on the Phoenix Audio website. The first was to mute the microphone in Windows playback settings. This setting adjustment is important because it prevents an audio loopback when you speak into the microphone.

The other important recommendation called for setting the Windows playback volume to a comfortable level. Another way to control the volume of the Duet is through the volume controls on the unit itself. On my PC, I found that setting the Windows volume first was better than doing it the other way around. In this test, I set the Windows volume level between 50 or 60 and adjusted the Duet’s volume control as I played my favorite MP3 tune.

Although I mentioned earlier that you don’t have to install any software for the Duet, there is one utility Phoenix Audio recommends that I will find quite useful. The utility is available from their website and it gives you greater volume control of the speaker and microphone (visit www.phnxaudio.com). After installing this utility, I immediately saw the value as it produced much better sound from the unit after some minor tweaks.


The echo cancellation algorithm is the heart and soul of the Duet. It’s fast and accurately measures the crossing point between the ‘fair end’ and ‘near end’ audio signals. This is the basic principle behind echo cancellation; identifying these two signals and knowing which signal to cancel.

Volume control on the Duet

At first glance, the volume controls looked straightforward and easy to use. The buttons are identified by up and down arrowhead symbols and are comfortable when pressed. For a novice or first time user, the buttons could be a little confusing. It’s not clear which button raised the speaker volume, or which one lowered it. Personally, I feel using the [+] and [-] symbols would have been a better design choice.

Mute Feature

Between the volume buttons is the mute button. It’s strategically placed, making the mute feature natural to use. When muted, the LEDS around the volume control flash. The flashing feature comes in handy, especially for those who mute the microphone to have a side conversation and later forget they had the microphone muted.

Microphone Range

The effective range for a single Duet is about a radius of 8 ft. To cover larger rooms, you can daisy chain multiple Duet Executives and there is no limit to the number of units you can daisy chain.

You will, however, need a daisy chain kit and the AC power adapter that comes with each unit. Each daisy chain kit contains an extender cable and a terminator. You can purchase the daisy chaining kits for around $14 each and be sure to mention this to your sales rep if you plan to daisy chain multiple units.

Daisy chaining multiple Duets is an easy task. Connect one end of the daisy chain cable to the first Duet and run the other end to the next Duet. After running the cable, plug in the terminator into the last Duet in the chain.

Image of the Duet with the daisy chain terminator installed.


My overall impression of the Duet was very positive. The overall playback quality was loud and clear. It was simple to set up and easy to use, a big plus for novice users. I highly recommend it to anyone planning to join a video conference and use audio concurrently.

Visit our video conferencing equipment page to view a complete list of recommended hardware for Nefsis.

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