by Neil Bauman, Ph.D.
Room loops (inductive loops) are wonderful to help hard of hearing people hear their TVs and stereos without blasting everyone else out of the room (or house)! However, few people really understand these loop systems. Here are six questions about such loops a man asked me. I think my answers will help you too.
1. “It says the maximum loop size is 80 feet. Is that square feet or linear feet?”
When you are talking about loops there are two ways to measure the room to be looped—the circumference of the room (the length of wire needed to go around the room), or the area of the room (the number of square feet the amplifier must be capable of effectively covering.
The common house-sized amplifier (the Univox 2A) officially covers about 400 square feet. This would require about 80 feet of wire to go around a room 20 ft by 20 ft. In actual fact, in a number of places including my own home, I’ve connected the Univox 2A to 100 feet of wire with no problems (approximately 625 square feet).
2. “How powerful is the signal put out by this amplifier? For example, I’m running this wire in a basement. Would I be able to hear the signal coming from the loop on the floor above, as long as I stay within the looped area laid out below on the corresponding floor?”
Yes, for sure—unless you have a metal floor. For example, I have my loop strung around the floor joists in my basement—and it works on the main floor just as well as if I had put it on the top side of the floor. You should also be able to hear it on the main floor of your house too. In fact, the loop on the ceiling of the basement should cover the basement, the main floor above it, and the upstairs above that too!
With such a loop system, you would be able to freely move around in that area and still hear beautiful clear sound—just as you would if you were sitting in front of your TV.
3. “Would this amplifier work in conjunction with, say, a stereo amplifier to provide more output and thus a longer length of wire?”
No. You see, the power going into the loop is limited by the power output of the loop amplifier, not by the power coming into the amplifier. The input signal from your TV or stereo just needs to be strong enough to drive the loop amplifier. If you want to cover a larger area, you need a bigger loop amplifier such as the Univox PLS-100, 300 or 700. Contact us for information on these commercial units.
4. “If using a microphone with the unit, do I need a pre-amp to boost the power of the microphone? What kind of microphones are best suited for this unit?”
No, you don’t need a pre amp. Just plug the microphone into the microphone jack on the back of the Univox amplifier.
The microphone jack is a 1/8″ stereo jack—but I think any 1/8″ mono plug will also work just fine. If you want a lapel mic, the lapel microphone works just great. You can try any mic and see how it works if you already have a mic.
5. “Is this unit only capable of outputting mono signals, thus requiring me to purchase the stereo to mono adapter?”
The patch cord that comes with the Univox 2A loop amplifier has two RCA plugs on it—one each for the left and right stereo channels—but the other end merges the two into one signal. You see, room loops by definition are mono devices (since both hearing aids pick up the same signal) so you normally merge both channels into one. Thus you hear both channels in each ear all “smooshed” together—what I call “dual mono”.
6. “What exactly is the advantage of a double wire loop?”
A double wire loop is not necessary, but it typically gives you a stronger signal. However, since I use 18 gauge lamp cord (and it has two conductors), it doesn’t do my Scottish heart any good to pay for two conductors and then waste one! That’s why I use the double wire loop.
You can learn more about these wonderful loop systems in my article, “Loop Systems—The Best-Kept Secret in Town!“