Re [AG-TECH] Tabletop-Room mic with integrated echo canceling

Michael Braitmaier braitmaier at
Thu Jun 21 01:47:13 CDT 2007

Hi Chris!

Christoph Willing schrieb:
> On 21/06/2007, at 7:03 AM, Ed Brannin wrote:
>> On 6/20/07, Michael Braitmaier <braitmaier at > wrote:
>> Hi everyone!
>> [snip]
>> I decided for a solution which is in the beginning a bit more work. I
>> ended up buying the following DSP-EchoCanceler-Board
>> Basically it does the same as their PCI-Card which however only fits in
>> Desktop-PCs. (see link for information: 
>> We've had a SOHO card for a while, but never installed it until 
>> today.  Sadly, it performed just like the hardware listing said:
> The performance description in that particular hardware listing is 
> open to wide interpretation -
>     "neither local nor remote sites noticed any audible difference 
> from that produced by our standard setup"
> since it depends the status of the "standard setup".
> Perhaps the author could elaborate on whether the standard setup 
> includes working echo cancellation, or has none.
> chris

My experience with the DSP version was good so far, however it needed 1 
upto 2  seconds to adapt to new speaker levels, or changed distances 
between mic and speaker.
Unfortuanetly the production environment I used it recently, consisted 
of an old palazzo in Bologna/Italy which didn't provide the best 
accoustic environment due to high rooms with
half-sphere roof charactersistic, which itself already caused a certain 
echo or hall effect. So this was not the best opportunity to completely 
test echo cancelation.
However we plan to continue the use of the device and I hopefully can 
give an update on its echo canceling capability in the future, when we 
have more results.
Our intial tests in the office over AG with a room based node however 
were  fine.

>> It doesn't work.  At least, not in a small, square room with 
>> wall-mounted speakers.  We played a video on the computer, then 
>> watched Rat's talk levels match William Shatner's voice.
>> From your email, it's hard to tell if you're using their DSP board, 
>> or if you've just bought one and still need to put it together.  
>> Either way, I'd like to know: does your way of doing it actually 
>> cancel any echo?
>> Thanks,
>> -Ed Brannin @ RIT
>> edbrannin at
>> PS: So far, we've been most pleased with an Accumic PC.  We've also 
>> had mixed results from chaining together several of Phoenix Audio's 
>> Duet Executive microphones, but the seem to work in our current 
>> arrangement.
> Christoph Willing                       +61 7 3365 8350
> QCIF Access Grid Manager
> University of Queensland

Dipl.-Inf. Michael Braitmaier
HLRS - Visualization / Video Conferencing
University of Stuttgart
Phone: ++49 711 685 65996
Fax  : ++49 711 682 357

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