[AG-TECH] echo cancel?

Claus Endres claus at endresconsulting.com
Fri Mar 6 18:44:35 CST 2009

Hi Charles,

The Phoenix Audio SOHO echo canceller is the cheapest room-level
solution. We have built three nodes with it, and it works quite well.
This is a PCI card, so it is not suitable for a laptop.

The problem with it is that it is designed for PC level microphones,
not for professional level ones, so you need some kind of pre-amp
if you want to use decent boundary mikes. Suppression of hum is
not always easy with setups like that. It works well with the
cheap little plastic boundary mike that comes with the card.

Phoenix Audio have three other devices that avoid this problem. They
are essentially USB boundary microphones with built-in echo cancellers.

The SOLO is just a microphone, and it should work well with small
conference rooms where  you need only one microphone to pick up
all participants.. It needs separate speakers. We have not tried this,
we could not get one here in Australia.

The DUET adds a built-in speaker, and it works well for desktop
conferences with a single person. We are using one for that

The QUATTRO is a sophisticated four-microphone pod with built-in 
speakers. It is USB connected and performs echo cancelling, noise
cancelling and phased array steering of the microphones to
the identified audio source. In a room conference situation, it
is able to handle about a dozen participants around a table.
If you need to cover more people, you can daisy-chain multiple
units. In conference situations, the build-in speakers are not
able to produce sufficient volume (if you increase the volume, you get
echo artifacts). You need to connect external loudspeakers to it,
but that is easy and cheap with a set of ~50 W 2.1 PC speakers. In that
kind of setup, it works brilliantly.

All these units are plug-and-play both under Windows and Linux
(our room conference systems run Fedora Core9). I have no experience
with MACs, but they should be fine. To the OS, they are just ordinary
USB audio devices.

So take your pick according to the number of participants on your side:
a DUET for one or two, a QUATTRO without external speakers for up to
four, one or more QUATTROs with external loudspeakers for more.


Jeremy Mann wrote:
> On Fri, Mar 6, 2009 at 3:06 PM, Charles Nichols
> <charles.nichols at mso.umt.edu> wrote:
>> AG-tech-
>> Is there an inexpensive way to echo cancel?  I'm using a MOTU UltraLite for
>> audio, with my PowerBook, and am getting feedback.
> Charles, I have built two AG nodes that use the SOHO Echo Canceling
> PCI card. It works surprisingly well.

Claus Endres                | Phone:  +61-3-5998 2310
Endres Consulting Pty. Ltd. | Mobile: +61-418-595 136
10 Facey Road               | Fax:    +61-3-5998 2540
Devon Meadows, VIC 3977     | claus at endresconsulting.com

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