Dorset Sound & Communications

Sound system design for the 21st Century


Conference Centers, Delegate Systems, Multi-Purpose Rooms

Delegate and Voting Systems - Sennheiser, ListenTechnologies/DIS, AudioTechnica Spectra Pulse, RevoLabs
Sometimes called congress systems these are used when an organization convenes a group of members or delegates for discussion and action.  In this case each participant around the table(s) has a microphone station. In the simplest system each mic feeds into an automatic or manual mixing system which feeds sound reinforcement and recording systems. We built a system such as this for the 9Marks church business training group. It consisted of about 16 desktop mics, cableing, automatic mixers, an amplifier and a digital feedback controller. The system electronics are built into a flight case allowing them to set up quickly at their home church or carry it across the country for a conference elsewhere.  It can be hooked into portable speakers or a local sound system.

A recent variation that has been gaining popularity is wireless. AudioTechnica Spectra Pulse and RevoLabs produce systems that allow a moderate number of participants to each have a wireless mic. Coordinating wireless radio frequencies is an ardous task that has forced them both to develop different modes such as digital and spread spectrum transmission. Much like the simple systems mentioned above, these do not incorporate the advanced features, but the AT system will accommodate 14 participants and the Revo system up to 32 microphones. Tabletop, desk and personal mic models are available.

Very sophisticated systems such as those produced by Sennheiser or DIS (US distributor Listen Technologies) can incorporate chairman controls, filibuster functions, voting and integrated station speakers.  These used to require masses of thick cables with big chunky multi-pin connectors. God help you if one broke. Today most of these systems use commonly available network cables and connect from station to station.  There are several manufacturers building fully wireless systems. These systems are expensive. The wireless even more so. A great deal of planning and evaluation is necessary prior to buying.

                        Presentation, boardrooms - Sennheiser, K&M, AudioTechnica, QSC, Atlas Sound, Biamp
These are hybrids of professional systems, teleconference systems, theater/home theater systems and delegate systems. How the system is designed has to take into consideration the size of the room, the functions required, the number of participants, the number of millionaires and the aesthetics of interior design. With Internet, video and computer displays, screens, projectors and remote control systems these can be some of the most complicated AV designs produced.

                        Training - AudioTechnica, Sennheiser, Biamp, Atlas Sound, QSC
Training rooms are usually set up to accommodate a large group of participants brought together with an instructor. These systems can be fairly simple. Most information comes from a single presenter. Usually there's a wireless mic or two, a wired lectern mic and wired or wireless mics for class questions or response. Video is rounded out with a screen, projector, DVD player and computer for Powerpoint type presentations. Most such rooms are equipped with enough ceiling speakers so each participant hears the same as any other.

Multi-purpose room - Commercial and professional equipment
A multipurpose room is used for different program configurations. It may be set up theater style, connected tables, small groups, a large circle, crescent shaped seating, or no seating for a reception or event. The focus could be on any wall, the center or nowhere in particular. The mecurial nature begs for ceiling speakers, inputs on all walls or the floor and wireless mics.  Most of the time video resources are portable.

Room Combining -  Biamp, FSR, QSC
When a facility has a number of rooms that can be opened into each other to expand or divide space to meet the need of each event, a room combining system is required.  The system can be as small as two rooms. It can be as large as eight or ten rooms. This is another case where it can be as simple or complicated as required. A simple system has a main room where all presentation takes place and speakers in each additional annex room are switched in as needed. The annex rooms never have need of independent sound systems. The second case has independent AV systems in some or each of the annex rooms.  When combined each annex system is capable of feeding the combined sound system, no matter how many rooms are added. This is often seen in convention hotels or large training facilities.  It used to mean a whole rack full of amplifiers, mixers and relays. Nowadays, modern digital signal processors with simple remote controls have made designing complicated room combining systems relatively painless.

Language translation/Hearing assistance - Listen Technologies, Williams Sound, Sennheiser, Ampetronic
Hearing assistance comes into play when a corporate facility has more than fifty fixed seats or hosts paid events. It is described in the federal Americans with Disabilities Act (ADA). You have to provide hearing assistance for 4% of the seats. On the other hand, it's just good business to make hearing assistance available to attract and keep good employees or clients who may have hearing difficulties.  We are an aging society.

There are a couple of technologies available.  Infrared is probably the least used. It's great if you have a lot of closely packed training rooms as the signal does not bleed into the surrounding rooms. You can use the same personal receivers throughout without changes. Infrared is favored for security. Nothing leaves the room.

Inductive loop systems are the most favored in Europe and not so popular in the US.  The room served is surrounded with a loop of wire whose ends connect a the loop amplifer which is attached to a sound system. Quality has improved markedly in the last 15 years. Low bleed, counter polarity fed systems can be designed, but bleed from room to room can be a problem. Loop popularity comes from needing dedicated receivers. The signal can be picked up by telecoils in individuals' hearing aids. Nothing for the owner to maintain. It can be problematic as telecoils are not as prevalent in the miniaturized in-ear hearing aids favored in the US. Personal receivers are available for users wihout telecoils. The site has to be tested for stray electromagnetic interference prior to sales. A big power transformer on the floor below can make the whole thing useless. I have about six facilities that requested loops and are quite happy with the result. With attention to specification and installation, these can be the most trouble-free systems

The most popular system in the US is FM transmission. Not only are the equipment and installation costs relatively low, but systems such as those by Listen Technologies can accommodate multiple frequencies in a facility using button tuneable receivers. They transmit on a federally protected disability assistance band, so interference is rare. With a several hundred foot range, users can walk out of the room and still hear their program. They also make small wireless receiver speakers and stationary receivers (to connect to other sound systems) that make it possible to use the signal to extend audio to other rooms, an office or a lobby. The transmitter is a single half-space chassis with an antenna that is attached to the sound system. No extra cable or mounted emitters to increase installation costs. We used to joke that with old Williams Sound systems you could ball up the cable antenna, pitch it in a corner and the thing would still work. It's simplistic, but illustrative.

Maintenance is the usual problem if you make personal receivers available. Someone has to test them, change batteries, maintain earphones, make sure they're returned and be responsible to see that malfunctions are repaired.  Depending on the system, personal receivers can run from under $100 to over $250.  Losing a couple due to carelessness or a walk-away can be a substantial cost. You have to have a check-out/in system. Listen makes recharger cases and rechargeable batteries available to simplify the task. It makes loop systems very appetizing were it not for the dilemma of typical American hearing aids.

I ganged the above with language translation as they both often use the same equipment. The big difference is that a language translation system has to provide for a translator with a microphone and some way to hear the presentation in a place where they do not disturb the presenter as they chatter. Multi-channel infrared and FM systems predominate.  Think of the UN. Several transmitters can be installed to accommodate multiple languages and hearing assistance.  If it's a small facility a portable 'tour guide' system may suffice. At big critical events a translator switch console may be needed so two translators can relieve each other. Translation is a difficult, tedious job.

Please do not hesitate to contact DSC to help you design, install and maintain your conference room of training facility. We're here to be your resource.

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