A House United

by R. Maxwell
in Installations
Upgrading the historic structure to modern audio and AV standards proved to be a task of epic proportions.
Upgrading the historic structure to modern audio and AV standards proved to be a task of epic proportions.

Audio Upgrade at South Carolina’s House of Representatives Chamber Gets Bipartisan Support

The South Carolina House of Representatives consists of 124 part-time citizen legislators elected every two years to represent the state’s 124 separate single-member districts. Operating from the House of Representatives Chamber, officials recently oversaw a massive restructuring of the Chamber’s AV facilities, which in addition to legislative sessions, is also used occasionally for a wide range of special events.

Augmenting an impressive assortment of video display and projection capabilities, the space is now home to a sophisticated audio system that incorporates Distributed Mode Loudspeaker (DML) technology from Tectonic Audio Labs, over 150 microphones and a redundant networked QSC Q-SYS system for control of the various audio assets — all of which is ultimately under Crestron automation control.

Deliberative Designs Consulting, LLC, of Colorado Springs, CO, a consulting firm that specializes in providing acoustical solutions and integrated systems design for deliberative bodies (legislatures), conference facilities, performing arts centers, entertainment venues, and recording facilities, oversaw the design and implementation of the facility upgrade at the House of Representatives Chamber. Michael Schwartz, the firm’s principal consultant, working in conjunction with a variety of fabricators, engineering firms, AV integrators, and others, discussed the project.

“I have been a consultant to the SC House since 1998,” Schwartz reports. “In 2012, I started discussing a new type of system based on Distributed Mode Loudspeaker arrays with Charles Reid, the clerk of the House of Representatives and director of house personnel. We had first demoed many conventional loudspeaker systems, but after much discussion, Charles suggested I show him my ideas. I assembled a comprehensive report outlining my vision and then commenced to do several ‘proof of concept’ demos over the next two plus years. Charles wanted a dramatic improvement in the sound system that would carry the House into the future.”

The first step was to do a “brain transplant” with a new DSP system. Schwartz designed and had a contractor install a large new QSC Q-SYS system, with analog inputs and outputs to work with the existing equipment. With the new ‘brains’ in place, the plan was to transition to a completely new distributed and networked audio system to significantly improve in overall quality and speech intelligibility.

According to Schwartz, the second phase of the project began in 2014 and installation commenced during the summer of 2016 — in time for the 2017 legislative session. It was during this period that the new loudspeakers were installed, the Q-SYS platform was vastly expanded, and much of the other “heavy lifting” occurred.

The room’s age, historical nature, and naturally poor acoustic qualities created a uniquely problematic challenge for the design and installation of the technology.

‡‡         Inside the Chamber

Overall, the Chamber is about the size of a medium to large concert hall. This is a very stately facility with ornate trim around the wall and ceiling areas, encompassing more than 100 years of use with little change to the physical structure and architecture. Hence, it was important to implement the AV upgrade without detracting from the character and historical significance of the room. The room’s age, historical nature, and naturally poor acoustic qualities created a uniquely problematic challenge for the design and installation of the technology.

The chamber floor has the desk area for the 123 members on the floor of the chamber, surrounded by a brass guard rail, and a centered well podium. The rostrum spans the front of the room facing the members. There is seating along the side walls on four large benches. There are also two large staff workstation desks on either side below the daylight LED video displays (from IRC/Daktronics). These displays are used primarily for voting results, but can also display multimedia or still images. A large wooden “clock tower” behind the Speaker of the House podium rises above the rostrum platform up to nearly the ceiling in the center of the room. Two large motorized screens on each side of the rostrum can be lowered and are housed in decorative boxes. These are Crestron controlled and typically used with video projectors displaying an Elmo high-def document camera or Crestron DigitalMedia presentation graphics / multimedia playback.

A balcony — referred to as “The Gallery” — has seating for 200 guests, allowing the general public to watch proceedings.

Consultant Michael Schwartz

‡‡         The Speakers in the House

Two main customized loudspeaker arrays attached to the custom Daktronics LED voting displays (“scoreboards”) on each side wall adjacent to the rostrum were designed by Deliberative Designs and Steve Carter at Columbia, SC’s Custom Welding and Fabrication. Custom engineered Tectonic Audio Labs DML loudspeaker panels are affixed to the far left and right sides of the scoreboards. There are three DML panels on each frame, and two Stage Accompany compact ribbon drivers (provided by Tectonic). These loudspeaker systems reside in custom cantilevered arrays. The design facilitates the safe placement of the arrays above people’s heads and enables the display door frames to be opened to access all of the electronics behind the displays.

These display / loudspeaker arrays were designed with extensive vibration control to prevent visual distortion artifacts from showing on the LED displays due to speaker vibration. Custom isolating neoprene rubber stand-offs were designed for the weight of the speaker components in the shear direction, and were combined with special 3M vibration isolation adhesive neoprene rubber tape and foam isolation blocks. Both the front and rear of these arrays are open acoustically to work properly with the Tectonic DML panels, which are dipole devices.

Tectonic speakers were selected for their unique form factor and audio performance. The Tectonic flat panel DML design differs substantially from conventional loudspeakers that use uniform pistonic motion to create sound. The primary goal with a conventional loudspeaker design is to ensure the diaphragm does not have any anomalies — i.e., that it does not “break up” in its passband. Breakup, however, is inevitable, so the secondary goal is to move the frequency of this breakup as high as possible so that when it does occur, the crossover filter has significantly reduced its level.

By contrast, distributed mode loudspeaker (DML) technology is designed to break up and not just move as a uniform piston. This break up — i.e., modal behavior, is intentional and engineered to produce a diffuse sound source that correlates at the human ear. Conventional drivers are either point-source or a line-source with fixed size radiators and, as such, exhibit a narrowing pattern at higher frequencies and have strong—both destructive and constructive—interactions with room boundaries. DMLs, however, are a diffuse sound source and produce 165 degrees horizontal and vertical coverage at all frequencies within a range of approximately 90 Hz – 7k Hz. They are highly resistant to disruptive room interactions, especially within the human vocal range. Hence, they are highly intelligible, even in less than optimal acoustic spaces.

“In addition to the main arrays,” Schwartz added, “there are two front member fill speakers, attached to the opposite side of the IRC/Daktronics display frames, that extend up to the wall end at the window alcove. Each of these incorporates a single Amina DML panel and a Stage Accompany compact ribbon driver on a truncated Tectonic waveguide cut to size. There are four standard custom-finished Tectonic PL-11 loudspeakers mounted in the window alcoves under the balcony on the side walls that serve as member side fills. These are positioned on custom pan/tilt mountings just below the balcony railing. All speakers are bi-amplified, and are driven by 18 individual QSC power amps located throughout the facility, including CX1100 two-channel, CX168 eight-channel, and CX254 four-channel models.”

When queried about his reason for selecting the Tectonic Audio Labs DML loudspeakers, Schwartz offered the following, “When using dynamic mics, we are able to achieve considerably higher gain before feedback with the DML panels as opposed to conventional loudspeaker designs. This, combined with the advanced DSP techniques we utilized, meant we could implement a far louder, far clearer, and far more intelligible system by using the Tectonic DMLs.”

On the rear wall at either side of the main entry doors, Schwartz and his team deployed custom rear wall arrays—each consisting of a Tectonic DML panel and a Stage Accompany compact ribbon driver and Stage Accompany waveguide. These are mounted on a custom fabricated pan/tilt aiming device located behind a custom polished brass screen. They are mounted in an alcove with two Sony 4K Laser projectors, which provide the image for the front drop down screens.

Low frequency support is via four QSC KW181 single-18 subwoofers — two per side — and custom finished to match the window alcove paint color. These are mounted in the window alcoves at the balcony level, directly above the main left and right arrays mounted on the LED display frames. A pair of custom-finished Meyer Sound MSL-4 powered High-Q loudspeakers also reside in window alcoves at the balcony level for Gallery sound reinforcement.

Completing the loudspeaker assortment, there are two custom mahogany coaxial wedge loudspeakers (custom manufactured by Deliberative Designs) at the rostrum. These are used for spot monitoring by the Clerk of The House.

The room’s “scoreboards” can be used to displays voting results and are flanked by the main P.A. speakers.

‡‡         Microphones Everywhere

On the input side of the equation, microphones are seemingly everywhere. There are two extended gooseneck hypercardioid Countryman dual element podium mics. One is located at the Speaker of the House’s podium on the rostrum and another is used for the members’ Well Microphone podium, which is located on the chamber floor near the center front of the rostrum. The reading clerk’s position — located to the right of the Speaker of the House at the rostrum — is outfitted with a custom Countryman headset microphone paired with a dual Lectrosonics Digital Hybrid Wireless system. There is also a handheld condenser Lectrosonics wireless transmitter for use during special events, by mobile guest speakers, or to field questions from the gallery or floor of the chamber. These are switched on and off locally via an LED illuminated switch or via Crestron control.

There are 123 member desk microphones located throughout the floor of the Chamber. These are custom dynamic microphones utilizing Shure SM-62 omnidirectional broadcast mics fitted with Beta 57 secondary windscreens. According to Schwartz, “They were chosen for their lack of proximity effect, internal rubber isolation for low handling noise, and omnidirectional pickup pattern. These mics are switched on and off by the Crestron and the Q-SYS systems, either from a large touchscreen controller at the reading clerk’s rostrum desk position, or from any computer or tablet connected to the system. For an authorized user, remote control is also available via the Internet or campus-wide intranet.”

Of particular note, Schwartz’ Deliberative Designs Consulting designed and manufactured custom dual spring-loaded, endless loop mechanical cord reelers for use with the member desk mics. These reelers can extend upwards of eight feet. Whenever a representative picks up a microphone and pulls the mic toward them, the system locks the cable to the desired length when the person stops extending the mic. Upon completion, the cable then retracts with a single tug on the cord and returns into its housing.

Signals for these desk microphones are run approximately 200 feet through high quality individual mic cables to an equipment room on another floor of the statehouse. This is where the main Q-SYS Core processors, input I/O Frames, and standard networked switches are also located.

The system needed to be able to accommodate both normal legislative work, plus any special events that may be required. There are 26 special event microphone inputs, used for joint sessions between the House and the Senate, model student legislatures, and many other functions (such as panel discussions below the rostrum, and/or musical performances by choirs, guest artists, or chamber ensembles). These microphones can be selected via the Q-SYS GUI for hands-off automixing or mixed by a house technician on an iPad or computer. These are switched on and off locally via an LED illuminated switch or via Crestron control.

‡‡         Inputs, Outputs and Control

Each microphone signal is configured with a Y-splitter and terminated to the same input channel on two separate 16-channel QSC Q-SYS I/O frames, each fitted with four 4-channel studio grade microphone preamps. Due to the high input impedance, it’s possible to bridge the microphones to two input frames, only one of which is active at any given time.

On all outputs used in the system, the outputs of two I/O frames are connected directly together, along with the feed wire. This is possible since the I/O frame outputs are relay controlled and only one of the pair of I/O frames’ outputs are active at any given time—all under Q-SYS control.

The first I/O frame acts as the primary unit, with the second I/O frame functioning as a redundant backup. If a fault or data packet loss is detected by the Q-SYS system, it will automatically switch to the backup frame without signal interruption. In the event of a non-data equipment failure, the unit can be switched manually to the backup from the User Interface GUI on any remote or local computer connected to the network. The system then automatically sends an email to the techs describing the failure mode, the piece of equipment that failed, it’s location, and date / time of the failure, thus providing continuous operation of the sound system while also allowing repair at a convenient time without interrupting the proceedings in the Chamber.

There is a total of 36 16-channel Q-SYS I/O frames used in the system for inputs and outputs (both analog in/out and QSC DataPort channels), in six discreet physical locations around the Statehouse and Chamber. Signals can be sourced from, or synced onto the audio network from each location. Each of the six locations uses a pair of standard network switches, and all are connected with a pair of single mode fiber optic cable strands back to the switches. The output of each Q-SYS I/O frame is a Gigabit Ethernet network (Q-LAN). There are two separate redundant local area network (LAN) connections from each frame: LAN A and LAN B. Each are routed via two dedicated audio VLAN’s to a different large “Core” data switch (two stacked switches) with 96-Gigabit Ethernet ports plus eight single mode optical fiber ports for each LAN.

These Core Switches are routed to the two QSC Q-SYS Core 4000 processor via LAN A and LAN B. An external control VLAN network port is also provided to a local Dell control computer, which is used to control the cores from the Crestron system and connected control computers, and to run the Q-SYS Designer Software. Each of the Core DSP processors is capable of up to 1,024 networked audio channels In and/or Out. Identical configuration software runs concurrently on each of the cores, thus enabling immediate changeover in the event of a failure. The networking scheme, named Q-LAN, conforms to the new AES-67 interoperability standard, ensuring future compatibility. All the data switches used are Brocade Networks models and are compatible with Q-LAN.

“One of the key attributes of this system, other than standard Ethernet networked audio and AV connections, is the fact that, with the exceptions of the microphones and reelers, the entire active electronic signal chain is fully redundant,” Schwartz explained. “This means that for every device from input to speaker outputs, there are two devices available to perform the intended function. This extends even to amplifiers and loudspeakers. To the House and its members, the net impact is that the system never appears to go down, even if a component fails, it always works”

One of the facility’s QSC Q-SYS and amplifier racks.

‡‡         Bringing it All Together

“With this system, each desk and special input has an extensive series of controls for filtering, equalization, automatic gain control, compressor/limiters, and gain sharing automixer/matrix feeds,” Schwartz explained. “The previous system’s active feedback reduction system has been maintained, which allows increased system gain before feedback on each microphone. When combined with the inherent advantage of the DML loudspeaker design, an incredible amount of gain can be achieved before the feedback threshold is reached. All outputs also have extensive drive processing, including multi-band dynamics, equalization and notch filtering, protection limiting, metering, etc.”

“The Q-SYS platform also provides full Core processing, I/O frame, amplifier, and loudspeaker remote control and status monitoring, as well as the capability for an advanced signal localization technique,” he continued. Members are located throughout the large Chamber floor area, but if someone is seated behind and to the right of a member, the sound appears from the direction of where that particular representative is sitting, which gives an aural cue as to their location.

From there, the signal is reinforced throughout the room for maximum intelligibility. The various loudspeakers are positioned throughout the chamber in support of this aural positioning, as well as for stereo imaging when being used with multimedia playback sources. With media playback, a sense of stereo field is maintained, regardless of the listener’s position. The system also automatically tracks the ambient noise level in the room, correcting for current ambient noise levels automatically.

In closing, Schwartz offered these final comments, “This has been a massive project, and let’s not forget that video, related multimedia support, voting system, fiber optic data networks, streaming, mass communications/emergency notification systems, alarms, signaling bells, live broadcasting, extensive press feed outputs throughout the facility, systems for the hearing impaired, plus campus-wide signal distribution are also an integral part of this project. There were numerous people involved and I want to say thank you to everyone for their expertise and dedication to making it all come together. It’s been an honor working with you all.”  

For more information, visit www.qsc.com