Documentation for Project #3 - Ambisonic Soundscapes in Three Dimensions

The ACTLab surround system has had multiple input formats but no access for exteral multi-channel analog inputs; a DVD was required to provide the AC3 audio for 5.1 presentations. Thanks to the RTF department's AV folks who installed a snake with balanced inputs specifically for this project.

I acquired some Yamaha HS80M near-field monitors two days before presentations (with eager anticipation of using them to build a surround system of my own) which I used for the lower set of speakers. (I had them out of the box long enough to confirm that they worked and to play my presentation a few times, switching between the upper and lower sets of outputs. I realize the issues of using near-field monitors in a far-field situation, but so be it.)

My Focusrite Saffire 26 Pro i/o has 8 analog outputs, from which I assigned 4 outputs to the top set of speakers (The front center channel was unused.) and 4 to the lower set. I derived the LFE channel from a matrix box I built to sum the 4 lower outputs to a mono signal which was then low-pass filtered at 125Hz with a Yamaha DEQ7 digital equalizer. This also gave me a level control to balance the subwoofer with the rest of the system.

The cabling for the lower speaker system was installed on the morning before presentations. I also located power outlets so I would have the proper extension cords.

The morning of presentations I arrived early to setup the system, then ran pink-noise tests to adjust upper and lower speaker system volume levels. I played only the first few seconds of my actual project just to be certain that the levels were still valid.

It was show time!