[AG-TECH] SUMMARY: echo cancelling audio solutions for AG setups

[R. P. Channing ["Rick"] Rodgers]

Dear AG Colleagues,

In our search for a cheaper, simpler echo-cancelling audio setup for the small
conf. rooms to be used at our UCSF AccessGrid nodes, we have received *many*
very helpful comments from the ag-tech mailing list.  I thought everyone
involved deserved a concise summary.  Starting from the most expensive:

Clearly, for larger spaces, the ClearOne (formerly Gentner) XAP400 can not be
beat, but it is expensive ($3000) and takes time and skill to configure
properly.  It has the advantage of accepting not only 4 mic inputs, but a phone
connection as well.  The Polycom Vortex EF2241 is roughly equivalent in specs.
and cost, and one respondent thought it might have a superior configuration
interface.

The ClearOne RAV600 and 900 ($2200 and up) are bundled systems, with an audio
mixer, microphones, speakers, and wireless control device.  They do require
some configuration via an attached computer, but this process is claimed to be
simpler than that required for the XAP400.  They also gets strong reports from
users, and seem to be attractively flexible.

For smaller rooms, where speaker-to-microphone distance is roughly constant,
the ClearOne AccuMic has excellent reports.  It is a microphone only.  At ~$550 
(street price), it does not require configuration.
There are two models: the VC (which uses RCA plugs for its connections) is
identical to the original AccuMic II in every way save the name, and the PC
(which uses 1/8" phono jacks for its connections) is a variant with slightly
lower gain settings, and may be more appropriate for use with the audio in/out
connections on PCs and Macs.  It appears that you can gang a second unit onto
the first if you need wider coverage.  One group reported great results in a
larger room previously covered by use of a XAP400.  This seems such a
generically useful device for conferencing that I have ordered one for myself
today.

There is an ever-growing number of even cheaper solutions for microphones,
though most of these seem geared toward desktop conferencing and are aimed
at the consumer market; the online documentation for most is sketchy.  
The VRVS (CalTech/DoE) group has documented their experience with such devices:
   http://www.vrvs.org/Documentation/Recommendation/audio_systems.html
(which suggests that the cheapest echo-cancelling solutions for anything
beyond the desktop are ~$200).

It's great to have a range of options, even if it does initially complicate the
decision-making process.  :)

Sincere Thanks to All, Rick Rodgers

--------------------------------------------------------------------------------
R. P. C. Rodgers, M.D. * rodgers at nlm.nih.gov * (301)435-3267 (voice, fax)
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http://lhc.nlm.nih.gov/staff/rodgers/rodgers.html