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Technology Showcase: Room Combining

Room combining systems do more than just combine rooms.

Technology Showcase: Room Combining

Feb 1, 2005 12:00 PM,
By Daniel Keller

Room combining systems do more than just combine rooms.

The ancient proverb tells us change is inevitable. And adapting to change is key to survival. The ability to change and adapt to new conditions is an invaluable asset, both in nature and in AV systems design. It’s also the basis behind room combining systems.

MARC room combine installation at the Kalahari Water Park Resort in the Wisconsin Dells, Wis. Photograph courtesy Andrew Kurth, Intelix.

The science of room combining has evolved at an exponential, even breakneck, pace over the past few years. But the concept itself has been around in its most basic form for many years. Factors of cost and convenience have always affected the ability to reconfigure a system for multiple uses. Hotels, convention centers, houses of worship, and other multi-use venues require flexible systems to adapt to their varying needs.

Early efforts at room combining were rudimentary at best: A simple matrix switcher and a few relays triggered by a movable wall created a larger room from two smaller ones. This type of system is still used in many hotel conference areas. However, with the advent of digital technology and the advanced routing and processing capabilities of audio via Ethernet, today’s room combining systems are capable of solutions an order of magnitude more complex.

The flexibility that digital audio brings to the table cannot be overemphasized. In the analog era, complex systems installed in hotels, office complexes, convention centers, and other larger venues — systems replete with elaborate matrices and several hundred miles worth of multicore and the associated terminations — would not have had a fraction of the capabilities of today’s systems. Digital technology has made it possible to create a single, highly adaptable and controllable system with far less hardware, complexity, and expense. The lowly Cat-5 cable has become ubiquitous, a worthy conduit for the multiple channels of multiplexed digital signal used for complex processing tasks and remote system monitoring and control. Amplifier and speaker monitoring, room combining, and the routing and re-routing of multiple zones within a venue are accomplished with a few clicks of a mouse, often from several miles away.

Technology that was once the domain of big budget installations is being employed with increasing frequency and diversity in smaller venues, which can now design and implement systems with features and price points previously beyond the scope of their projects. Houses of worship are using the technology to route audio throughout their campuses and broadcast it both terrestrially and over the Web. Retail establishments are creating multiple zones within the store, pumping one audio and video program into the Bed and Bath department and another into Young Miss. Elaborate, multi-room sports bars are bringing in multiple channels of cable and satellite offerings, easily reconfiguring their main and secondary screens based on the event du jour.

TOA Electronics NX-100 series


Although we tend to refer to any system capable of reconfiguring the audio as room combining, the term itself is something of a misnomer. These systems are just as often used for other functions, and involve the routing of multiple source signals to multiple destinations and the performance of complex processing chores.

Bill Schuermann, senior design consultant with Houston-based HFP Acoustical Consultants, agrees that the term is inadequate. “There are probably as many different types of room combining systems as there are clients who use them. What it essentially comes down to is selecting a number of different elements and assembling them to create a system that will function as seamlessly as possible for the end-user.”

“The term itself is something of an oversimplification,” says Matt Czyzewski, BIAMP Systems vice president of technical operations. “In many cases, we may in fact be dividing rooms, or taking two different sound sources, combining them, and sending them to a third destination. Just as often, we will be taking control signals and combining them, so that two discrete systems do in fact function as one. So there’s a lot more going on, but it all falls under the general heading of room combining.”


As Schuermann observes, the intended user will typically be somewhat technically inexperienced — wait staff or other hotel personnel, volunteers from a congregation, and so on. Hence, the ideal room combining system is the one with the simplest interface. “When I’m planning a project, I’ll consider what possible components and options are going to be used in the system, and combine as many different facets as I can to make it as foolproof as possible for the less experienced user,” Schuermann explains. “The more the system can operate itself, the better.”

Using our classic example, the movable air wall that combines the audio systems of two rooms when opened, Schuermann elaborates, “Other aspects of the system can be integrated to follow along just as easily — lighting, video, HVAC, etc. So when that wall moves, everything — a multitude of systems — is reconfigured automatically.”

BIAMP’s Czyzewski adds, “Most of the time, there is a significant degree of complexity going on beneath the hood in terms of programming and coordinating the systems. But, on the surface, it should appear so simple to the end user that anyone could operate it.”

Crestron RoomView application


As previously noted, there are as many different types of room combining systems as there are clients who use them. That said, there are certain aspects common to most room combining systems. Mic inputs, for example, are typically configured for a number of inputs per zone, usually in wall panels or floor boxes. Line level or other audio inputs, as well as video and other sources, may also be provided.

These inputs will typically connect to a mic mixer of some sort to generate an output from each zone. Depending on the specific requirements of each zone, this could be a manual or automatic matrix type mixer. In a room that might be used for conferencing, for example, an auto mixer can prevent feedback in the hands of inexperienced users by preventing multiple mics from being active simultaneously.

In almost every system, a matrix controller takes the audio output from each zone’s mixer and sums it to feed power amps or powered monitors. When two or more zones are combined, the audio feed to those monitors will consist of the sum of the individual outputs from each zone.

Multiple control points are also typically provided in multi-room systems. These can range from simple wall-mounted volume controls to elaborate touchscreens usually located at various points within the system. When the individual rooms are linked, these remote controls will also be linked. In most cases, there will be a single master control point, usually a touchscreen or dedicated computer, with full control of all aspects of the system. In larger installations, there may be several master control panels. Touch panels, in particular, are commonly employed for control because they provide an intuitive graphical interface that can be understood by even the most inexperienced users. This also makes the system more adaptable to future changes and expansion.

BIAMP Systems Audia interface


Although digital technology can certainly be an asset, Schuermann is quick to point out that in many smaller installations it’s an unnecessary complication.

“Digital and Ethernet fit into the equation only as necessary,” he explains. “In a smaller setup, such as our two-room scenario, it’s usually a dedicated operation. Where digital comes into play as an ideal technology is in a large-scale system, such as a hospital, house of worship, or multi-room facility — the more rooms, the more possible configurations, and the greater the degree of complexity.”

As Schuermann points out, the usefulness of digital technology is directly proportional to the size of the facility and complexity of the system. “For example, we recently did a project at the Hilton Americas facility here in Texas. The ballroom has 12 sections and three hallways; with the number of possible combinations of room configurations for that system, clearly, you need to go digital. In fact, we’ve got 75 Soundweb units in that system.”

Certainly, the more possible combinations there are, the greater the need is to make a system foolproof. And more is involved than simply keeping track of configurations. A typical conference room, for example, will have at least two possible locations for the dais, or head table. Depending on which location is selected, the room may need to be reconfigured for different speaker delays. Some mics may need to be attenuated as well, to avoid feedback from speakers that may now be closer to the audience in that part of the room.

In addition to automating setup configurations, digital brings a wide palette of signal processing options to the table. Most digital room combining systems offer a wide range of equalization, delays, and dynamics processing, making it possible to configure a number of scenarios in considerable detail, as well as doing away with multitudes of rack-mounted DSP boxes.

“Digital technology has given us a whole new palette to work with,” Schuermann says. “More colors, more speed, more flexibility, and more security. Creative design has really benefited. Years ago, when everyone had their own separate and discrete systems, it was much more of a challenge.

“A lot of the projects I’m doing today would have been much more difficult six years ago because there were no standards, or the standards were not quite there yet. There was a lot more hot rodding involved to make things work. We now have a common platform to work with, and the newer manufacturers coming into the market are able to work within those existing standards. Now everything is falling into place and the circle is getting bigger. It gives us as designers the ability to be far more creative.”

Another important and extremely useful aspect of Ethernet-based technology is the ability to monitor and control the system remotely. In many cases, this can be performed from some distance, making it very useful for facilities where maintenance is not always immediately accessible.

“We recently implemented a system down in Caracas, Venezuela,” Schuermann reports. “The logistics of trying to monitor or maintain that system are made far easier if we can do it remotely, rather than have to make a service call.”

SymNet Designer


Using digital technology in a room combining system also allows the designers to “idiot proof” the system using password protection. “The inexperienced user is very capable of inadvertently taking down the system, or at least reconfiguring it involuntarily,” Schuermann says.

Many newer products offer several levels of password protection, and allow various levels of permissible commands to be delineated depending on the user’s level of technical savvy. This helps to avoid the “What does this button do?” scenario with an inexperienced user.

Clearly, the individual needs of the users will also, to a large extent, dictate the degree to which the system is “idiot-proofed.” Larger performance venues — convention centers or sporting arenas, for example — typically employ dedicated AV personnel with a higher degree of technical sophistication; hence, the user interface for such a system can be more complex.

As Schuermann puts it, “We draw the lines based on who we’re building the system for, and what they’re going to do with it. In the majority of cases, the end user will be relatively inexperienced, and we want to design the system accordingly. It’s a means of protecting the client’s investment; by making the system self-sufficient, you’re giving the owner a better value for their money.”

BIAMP’s Czyzewski concurs. “Room combining should be as uncomplicated as possible to the end user. Our direct customer, the contractor, is of course more technically conversant, and our presentation of the products to them will be far more in-depth. But ultimately, when we design a product, we must keep the end user in mind and create the interface accordingly. If we can make it easy for our customer to implement the product features for the end user, we both win.”

TOA‘s NX-100 series incorporates a matrix switcher, mic preamp, and audio and data transport into a single unit. Applications include wide area paging, background music, and audio distribution for large-scale networks. Its D-901 digital mixer supports up to 12 mic/line inputs and eight line outputs, and integrates auto mixing, multi-band parametric EQ, feedback suppression, compression, gating, crossovers, delay, and other digital signal processing features.

Rane offers a full line of DSP-based products, many of which are popular in room combining systems. Its Drag Net software is a Windows-based application used to configure, control, and monitor the RPM series of programmable DSP-based products via an intuitive drag-and-drop user interface.

BIAMP Systems‘ Audia offers an intuitive drag-and-drop user interface for easily configuring and designing a system. The AudiaFLEX module offers up to 24 inputs and outputs, configurable in pairs using the EXPI and EXPO plug-in modules. The new Nexia line is designed with analog-specific I/O, offering presentation mixer, conference system, and speaker processor modules.

Australian Monitor Audio‘s new ZoneMix3 is a stereo zone mixer offering four stereo and two mic/line inputs and three stereo zone outputs, with five-stage EQ per zone and link output for cascading another unit. The company also offers the DigiPage zone paging systems, including the matrix switcher base station, remote mic stations, and wall panel control units.

Xantech makes a complete line of signal processing and control systems products, including a wide range of controllers, multi-channel amplifiers, remote control switchers, and other peripherals. The company’s MRC88 is an eight-zone, eight-source A/V entertainment system.

Atlas Sound‘s Varizone is a digital public address system providing for the design, configuration, and control of multi-zone public address systems. Offering a drag-and-drop PC interface, the system allows the user to set individual volume zones, adjust equalization and delay settings, schedule daily system events, and monitor for system faults, all from a remote position.

Crestron is widely known for its leading role in the field of controllers, in particular its innovative touch panel designs. The Isys I/O is a line of touch panel media centers that interface directly with the Media Manager series, which integrates AV device control, system management, and signal switching and routing. The company’s Room View software works with its control systems and touch panels to manage an entire network of AV devices and subsystems, including remote system diagnostics, tracking use of individual components, and automating tasks through scheduling.

Dukane Communications‘ 4A1445 universal selector panel can switch any of 11 inputs to a single output. It also includes a bypass function that allows it to connect with additional units for unlimited input capability. The company also offers relay selection panels, remote intercom amplifiers, and input and summing modules, as well as black box speaker controls and other distributed audio components.

Oxmoor‘s MCS system provides for combining audio and synchronizing local volume controls on any combination of up to eight zones, even if they are not adja-cent. The MCS line features combining systems for up to eight rooms. The MCS Mainframe houses line input for the audio source in each room to be combined and a logic card to set the various combine levels and background/paging levels. All of the functions managed by the mainframe feature non-volatile memory and are fully field programmable to meet virtually any combining configuration.

The MARC system from Intelix features room combining capacity for up to 16 rooms, with individual mic/line mixing per room, program distribution, keylock security, voice paging with auto ducking, and RS-232 control. The company’s MARC-E system adds TCP/IP LAN and Internet capability, increased baud rate, and front and rear communications ports.

Bogen Pro has long been a major player in room combining systems, offering a full line of matrix mixers, amplifiers, speakers, mics, office and paging equipment, and more. Its PM3000 ProMatrix preamp offers three balanced and unbalanced outputs, with programmable auto switching of inputs, while its PM3180 ProMatrix amplifier provides 100W, 60W, and 20W amplifier channels with 8V, 70V, and 25V transformer coupled outputs.

Symetrix features a line of modular, RS-485-based remote control panels for the SymNet Audio Matrix platform. The hardware is supported by SymNet Designer, version 5.5. The software/hardware com-bination specifically addresses the management of BGM sources and room volumes when zones are combined. Wall panels are linked together, allowing the selection of the BGM source and level adjustment from any remote located within the combined space. When rooms are uncombined, the panels become independent and control their specific zones. The system supports four BGM sources that can be distributed to up to 16 zones.

Crown Audio offers its IQ Network line, featuring products manufactured by Crown and other Harman companies, including BSS and JBL. IQ Networks can perform amplifier control and monitoring, digital signal processing, automatic mixing, routing, ambient noise system level control, and system and load monitoring. The company has recently introduced its Digital B-Chain network bridge for transferring multiple channels of uncompressed digital audio over standard fast Ethernet hardware. The bridge is for use in traditional 35mm, digital cinema, and e-cinema applications.

BSS, another Harman company, has long been involved in room combining and distributed audio with its popular Soundweb line of distributed audio processing products. The company recently launched a London range, which it says has a new core operating system offering more flexible and enhanced I/O configuration, more efficient DSP, lower latency, and greater capacity.

dbx offers the ZonePro line of digital zone processors, a suite of signal processing and control systems for commercial audio applications. The ZonePro products feature a wide range of professional-grade signal processing, as well as multiple forms of control and realtime programmable signal changes throughout the day or week. The ZonePro Designer software provides an intuitive interface and speedy setup wizard for configuring and editing all system parameters.

ClearOne Communications offers a full line of pro audio management and distribution devices designed for room combining and conferencing applications. The XAP line, in conjunction with the company’s G-Ware user interface application, allows the user to design systems, control and monitor parameters, and establish presets and macros to make instant configuration changes for a variety of room scenarios.

Innovative Electronic Designs (IED) offers its 8000 Totally Integrated Processing System (TIPS) series which, in addition to room combining in DSP features, also offers remote monitoring and testing, message storage and playback, and several other features, making it a complete turnkey solution. The company’s 3200 series DSP mainframe can provide up to 72 channels of audio inputs and/or outputs on configurable cards. Multiple frames can link together for larger systems.

Lake Systems, now a division of Dolby Laboratories, offers the Contour Pro 26 digital loudspeaker processor and the Mesa Quad EQ digital matrix processor. The units offer seamless integration with the company’s Lake Controller software interface.

QSC Audio‘s integrates signal transport, control, processing, and monitoring technologies into an Ethernet-based system. Based on the company’s RAVE (Routing Audio Via Ethernet) and BASIS components, the system combines CobraNet audio transport, system monitoring, and configurable DSP, accessable via an intuitive user interface.

For More Information

Atlas Sound

Australian Monitor Audio

BIAMP Systems

Bogen Pro


ClearOne Communications

Crestron Electronics


Dukane Communications

Innovative Electronic Designs (IED)


Lake Systems







Daniel Kellerwants to know what happens when he pushes this button.

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