Intercom systems

The process of selecting the right intercom system for a broadcast or post-production facility, as with any major equipment investment, is seemingly daunting. It can seem like there are countless options to consider, making it tough to even figure out what the first step should be.

To simplify this process, break it down into three main steps, in this order: Conduct a comprehensive inventory of your facility's needs, read up on the basics of the three main types of intercoms, and then start researching manufacturers.

If you want to find the best intercom for your facility, take a good, hard look at its communications needs. The first thing you'll want to know is how many users the intercom system will need to handle and how they will use it. This will help you gain a solid estimate of the number of separate intercom channels, including private channels, you'll need. Some good questions to get you going are: Who needs to talk with whom? Are there wide distances between various production areas? Are some of your operations mobile/remote? Will you need wireless intercoms, and therefore the accompanying number of headsets and base stations? Put together a user profile before you start shopping for an intercom system, and it'll be much less stressful.

Next, look closely at your building's infrastructure to determine the physical coverage you'll need from the intercom. Is the existing wiring in good shape? If so, it will be easier to integrate an intercom system into the overall equipment workflow. Check for easy access to cable runs. If there is more than one building, consider the distances between them. You'll need an intercom system that can provide communications across these expanses.

Most intercom systems on the market today can interface with a variety of other types of equipment such as telephones, four-wire devices, GPI/relays and IP, to name a few. Make a list of the gear you'll want to interface with the intercom to ensure the intercom will accommodate these needs. Also look into your IFB requirements. Does your facility need wired or RF IFB? A telephone IFB? On a related note, consider how your mixing console will interface with the intercom. A conversation with your head audio person would be helpful here.

Next, look at the staff members who'll be handling the intercom system. How much experience do they have with intercom systems? Do you think it'll be fairly easy to train them on the new intercom system's GUI? This is also a good time to determine whether your facility's daily workflow requires people to manipulate components of the intercom system quickly and on short notice. This is often the case with operations that handle a lot of live broadcasting. You'll want to make sure that the intercom system you choose has a GUI that is familiar to your staff members or is at least fairly easy for them to learn. That way, during busy production times, they won't waste precious seconds searching for a function.

Once you've conducted a thorough inventory of your facility's communications needs, make sure you are up-to-date on the basics of today's three types of intercom systems: party line, matrix and wireless.

Party-line intercoms

The party-line intercom is the backbone of most entry-level and midlevel communications systems and is best for entry-level and midlevel users. (See Figure 1.) As almost all intercoms use some party-line elements, an understanding of its workings is essential. The basic design principle is that the input and output outlets are married onto one circuit, with nulling circuitry being used to keep the two signals separate. Maintaining the null is important, so if you go with a party-line intercom, you'll want to add this into your regular maintenance cycles. Similar to a phone line, party-line systems use echo-canceling technology to keep talk and listen paths separate. They incorporate high-impedance bridging and a 200Ω termination circuit to keep the signal from diminishing when multiple beltpacks are added to the system. One major innovation party-line intercoms pioneered is the call signal, a convenient way to wake an operator up or get the attention of someone by flashing a light and/or placing a tone on the line. Some party-line devices will even buzz or vibrate. This is all delivered over a single microphone cable per channel.

Party-line systems can range in size from just a power supply and some beltpacks to multichannel systems, interfacing to anything you can imagine. Typical systems have a main station, remote stations and a bundle of beltpacks. They are plug-and-play and run on regular microphone cable. (20AWG or 22AWG wire is recommended.) The only issue with the cabling is that there is some voltage on these lines, so take precautions against mixing them with microphones, for safety.

Matrix intercoms

Matrix intercoms are becoming more prevalent these days. Their flexibility has made them quite popular with larger, more sophisticated power users. They employ four-wire technology (the simplest of communication circuits), and can interface with POTS telephones and standard audio paths, both digital and analog. One of their biggest benefits is that they enable point-to-point communications, allowing numerous private conversations within the system. In addition, the matrix architecture can accommodate many new fiber and IP interfaces and no shortage of useful VoIP and VoIP-like solutions, making it possible to use the system to talk not just within one facility, but across thousands of miles. If your operation handles a lot of breaking news from remote locations, many matrix intercoms can allow reporters and other staff members to access the intercom from a laptop interface, even if they are located thousands of miles away from the home studio.

Wireless intercoms

A third category of intercom systems is wireless. (See Figure 2.) Because of their inherent mobility, most broadcast and post houses use wireless intercoms, often in conjunction with a matrix or party-line system. The main things to consider when choosing a wireless intercom system is how well it will work with your facility's fixed intercom, how well it deals with RF interference, especially in environments with a large number of different wireless systems (such as a sporting event), and the frequency band on which it operates. There is a lot of UHF space available today, but because of changes by the FCC, most will no longer be accessible for intercoms in the future. Always insist on a test at the site before you buy. Look at wireless intercoms that operate at higher frequencies so you don't get an unwanted surprise when the FCC pulls the switch — as it did with 700MHz.


Once you've followed the two steps outlined thus far, you will be primed to start step three, which is researching intercom manufacturers' products. Now that you have a clear idea of your facility's communications needs, compare them with the features each intercom offers. No doubt, you will find the right match.

Ed Fitzgerald is director of customer satisfaction at Clear-Com.