Large audience & echo cancellation

[cedi]

Hi all.

I have a question for all you pro's.

I may have to implement a VC in a big conference room/hall with up to 100 participants (mostly audience).

Here is my concern. I have to put local audio on loudspeakers too, so everyone in the room can hear the (local) speaker. But this audio must be sent via VC to far-end also.
I'm concerned about "microphony effect" on local side. I have Tandberg 990 available. It has 2 XLR connectors (with integrated separate echo cancelers) and 2 RCA (audio3 and VCRin) without echo cancelation.

There should be 4 tablepod microphones (XLR) on 2 tables and 2 wireless mics for the audience.

Can you give me any hint on how to do it? Do I need external echo canceler, ...? How to connect everithing...?

Thank you for your hints.

BR,
Cedi

[tom9933]

Cedi,
We do this sort of thing all the time and typically we run everything through an operated mixer before it goes to the speakers or the codec. Basically attach all of the microphones to the mixer as if you were doing reinforcement and then take an aux send from the board to feed the input on the codec. Since it sounds like your Tandberg only has mic level connections with echo cancellation you will need to pad the aux (line level) send from the board. In addition to that you will also need to bring the feed from the far site (codec line out) back into a channel of the mixer. As long as you only send the microphones to the aux send you should be fine. A quick note, if you have not run a live reinforcement setup before then you might consider contracting that part out with a rental house. Also what do you mean by “tablepod” microphones? If you are referring to the flat microphones that you’d typically use with a vc system then you should consider using a different type of mic. Typically for a panel discussion or podium we would use a Shure sm58 with the appropriate stand.
Good Luck,