BISMARCK, ND-The thought of running a sound system consisting of more than 100 microphones without an AV tech to monitor the setup is the type of situation that keeps system designers awake at night. That's exactly the scenario technical services engineer Wayne Mastel at the Bismarck, ND, office of Minneapolis, MN-based AVI Systems had to contend with as he and a team of AVI Systems associates were charged with revitalizing the North Dakota House of Representatives' sound reinforcement system.
AVI Systems handled the design and installation of the system and, in the process, utilized the original layout concept that dated back to 1973 as a means of containing costs. The project was designed to provide easy access to multiple remote feeds of the proceedings for offices surrounding the chamber area, the press area, feeds for cable access, a feed dedicated to the campus internet system, one for the Journal Reporter at the rostrum, another for hearing assistance, and additional feeds that go from the Legislative Chambers to the main building and campus for access in remote office locations.
According to Mastel, "The North Dakota House of Representatives was looking for a system that would facilitate greater flexibility in terms of distributing program to the media and throughout the campus, as well as being able to accommodate future expansion. Since there is no dedicated AV person or department, ease of use was a priority. The facility management staff sets the microphones up, and then whoever is conducting the meeting runs the system from that point on. To keep matters manageable, the system is currently analog oriented in terms of its control functions, but utilizes extensive programming of automated mixing and signal processing functions."
At the rostrum, there are typically two Shure MX418 Microflex desk mics for the chief clerk and the speaker of the house, though an additional input location is available to accommodate a program source. The rostrum microphones are controlled locally and feed a Lectrosonics AM8 microphone mixer.
For the individual representatives on the House Chamber floor area, there are 108 Astatic Commercial Audio Products BUM-1 microphones that are updated versions of the 1982 model. "The client was emphatic about retaining these," reports Mastel, "as they are very ruggedly-designed mics that not only handle abuse well, but also have a grip to talk switch. Without a sound operator, each person must control their own microphone, and these mics are live only so long as a person holds the button down. This design eliminates unwanted audio feeds and goes a long way toward maintaining a clean, quiet environment."
To improve the performance of the Astatic mics, AVI modified the elements to enhance pickup performance. The microphones are individually tuned to the room and analog level control is provided so that as people come and go throughout the legislative process, they can set individual levels.
Seven Lectrosonics DM1612 digital automatic matrix mixers accommodate the mic inputs from the floor. These units are cascaded and, together with the AM8's output from the rostrum, all signals feed into a Lectrosonics MM8 programmable matrix mixer, which routes the various microphone sources to a series of subfeeds to accommodate the media. The MM8 also incorporates the inter-routing of the Shure DFR22 and DRF11 main room processors for mic EQ, which then proceeds to a Rane DA216a distribution amp that is primarily accountable for the media and cable access feeds. The rostrum and the floor microphones are processed as individual zones relative to the sound reinforcement part of the system.
Sound reinforcement for the main floor area is provided by Renkus Heinz special order MircoTrapk Series loudspeakers. Power amplification is provided by Crown CT410s that were part of the original system.