Brent Saltzman


Interested in all things technology with a passion for analog, design, audio, and anything that sparks creativity and imagination.


Adventures of a Biamp System Designer part 1

One of my many hats at work I wear is the the "Biamp Engineer" (as I call it) or the "Biamp guy" to everyone else. I design, troubleshoot, install, and maintain 15 different Biamp audio systems on our campus. I love working with our Biamp systems: there are literally a million ways to accomplish the same tasks and none of them are wrong. You have the flexibility to design as much as your imagination lets you and to me they always seem like one big puzzle to figure out.

Room 252 is a large amphitheater lecture hall designed for Health Science instruction and shared by our School of Medicine and College of Nursing. Nursing also uses Video TeleConferencing to include additional classrooms and a remote satellite campus in another city. There are 12 hanging microphones above the student seating to capture their comments and questions throughout the lecture for recording and VC proposes. It sounds simple, but this has been one of the most difficult rooms to work with audio-wise, so I may blog more about it in the future, but I would like to cover one design solution I did now. This room is powered by 1 AudiaFLEX and a Nexia VC to help with the hanging microphones (they were added after the AudiaFLEX was installed)

Problem: There is a wired microphone that is used when the Wireless Shure ULX-P lav's battery dies. It sits on the side of the podium as an open microphone so it's ready to go when needed. However because it's an open microphone it sends extra background noise down the video conferencing wire. The far end complains of echo, delay, and overall noise when the near-side faculty is lecturing, but nobody on the near side is complaining. What do you do?

Solution: Use the Ducker! Here's what I did:

I need to duck the wired microphone, but only for the videoconferencing output. I needed the ULX-P as the sense input so when the instructor is talking with that microphone, it ducks the other to cut the noise. The tricky part was to only affect the Video Conferencing output. Take a look at the layout (Yes, it's messy, didn't have much space to add all the lines for this)

Ducker area of 252's Audia Design

What is going on is the wired microphone coming out of the matrix mixer is going into the Ducker's input. Another line coming out of the Matrix is from the wireless mic into the Ducker's sense input. So now we have the ducker hooked up correctly, but how to only make it affect the VC out? I put a Standard Mixer block in down stream, post ducker. I connected the ducker's output, the wireless microphone's output and the VC Out of the matrix mixer and fed them into this additional mixer. Then the output of the new mixer would be sent to the processing and then the physical AudiaFLEX output. Now only the far side of the video conference will have their feed of the wired microphone "ducked" when the wireless microphone is in use.

Hope this is helpful to anyone trying to solve this or a similar problem.

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