Wireless Microphone Systems
Audio-Technica has been dedicated to advancing the art and technology of electro-acoustic design and manufacturing since 1962. The results of these engineering and production efforts can be seen in the effective use of A-T products in a broad spectrum of applications.
Audio-Technica microphones are found in daily use in major broadcast and recording studios, and relied upon by top touring musicians.
Here is everything you need to know about them to be an educated user / consumer.
All wireless transmissions start with a transmitter. The transmitter is the device that broadcasts the signal via RF (Radio Frequency) waves to the receiver. They can be in the form of a body pack transmitter with lapel or headset microphone, or an instrument cable. It also can be built into a handheld microphone. Better quality body pack systems feature a disconnect point between the body pack and its microphone. In less expensive units the microphone or cable is often permanently attached to the transmitter. In the event of a short in the cable, the entire receiver must be serviced rather than simply replacing the removable cord or microphone.
Any good quality transmitter should have an on-off /standby switch. This allows you to turn the unit on or off from the transmitter, or mute it temporarily. This mute (standby) is beneficial should you get a burst of feedback and you’re not near the sound system. The standby feature is also beneficial when you need to talk to someone without being broadcast through the sound system.
In a handheld microphone system, the quality of the microphone element is also a determining factor in the overall sound quality. In handheld systems, the microphone element is fixed to the transmitter and often cannot be easily interchanged. One benefit of body pack systems, is that you can often choose what quality or type of microphone you want, or can easily upgrade at a later point. You can start with a lapel microphone, then later purchase a headset, clip on instrument, or specialty microphone. Even a special guitar cord or microphone cable can be added to your body pack. All these components can be interchanged to make your body pack wireless system very versatile with multiple microphone or input types.
Receiver (often referred to as base unit)
The receiver plays the biggest role in determining the quality of a wireless system. The better the receiver, the better the unit will operate. After all, a broadcast signal is only as good as the unit that converts the airwaves bouncing around back into an audio signal to feed your sound system.
A Lesson on Receivers & Diversity?
Diversity is a term that is often used very loosely and incorrectly. Often you will see systems advertised as being true diversity when in fact they are not. Before getting into the differences, a brief explanation of how a receiver works is due.
Consider a wireless receiver to be like a radio that is preset to only receive one station and no other. It receives the signal via its antenna, converts it back to the original audio signal. This signal is then sent to the sound system for amplification. An often-asked question is… “Can I get two packs / mics and use them both on one receiver?” The answer is NO; you cannot receive multiple signals on the same receiver frequency. It would be like two songs broadcasting simultaneously on the same radio station. Here is another way to look at it. It’s happened to us all; just when you start grooving to a great song while driving in your car, another song you can’t stand starts creeping into your personal jam session. Within 30 seconds or so your radio is jumping between the two songs and you find yourself reaching for the dial in frustration. Wireless mics work the same way.
There are systems that come with multiple mics and a single receiver. This situation is where there are multiple receivers built into one “box”. They are still separate receivers. Typically these are entry-level units in an attempt to make multiple wireless affordable, often (but not always) at the expense of quality. Many manufacturers offer systems with both a body pack and a handheld. Most of the time you can use one or the other, but not both simultaneously.
- Non-diversity (often mistakenly called single diversity) is simple to explain. There is no diversity at all. You have one antenna and that’s it. When the signal fades, is interfered with, drops out, or becomes weak you may get bursts of static or unwanted noise. There is nothing the system can do when this occurs. Grin and bear it, and hope it goes away fast. There are better and worse quality levels of non-diversity systems. Any good non-diversity system should have one of two things either two antennas (one of which is a ground antenna) or an all-metal case (see Grounding below). The second antenna is a ground antenna. They are not rabbit ears.
- Di-Pole Diversity in my opinion is NOT Diversity, but rather creative marketing jargon. By definition it is when you have two antennas that feed a single receiver circuit. I say Di-Pole means two sticks. You have two antennas which does increase the quality ever so slightly but only by the degree of separation in physical distance and the odds of one being stronger in reception than the other. There is still no true backup on itself. They often look like a true diversity system and far too often are mistakenly or falsely advertised as such. Since the receiver does all the work, and there still is only one receiver and no backup on it, the reliability does improve, but only minimally in my experience.
- True Diversity is when the receiver has 100% redundancy in itself. There are two antennas, each has its own independent receiver circuit. This is all built into one chassis. The signal enters both antennas independently to its receiver. The signal of each receiver is tested roughly 600 times per second to see which signal is best. This allows seamless transition back and forth between the receivers. The testing circuit can vary in quality between brands and models and make a big difference as well. Some models test the signal strength and that’s it, while some systems add a second test for audio signal quality and compare the two results for even greater reliability. True diversity is by far the most reliable type of receiver.
Keep in mind that NO wireless system is foolproof. Every wireless system is subject to interference at some time, no matter how much you spend. The reason is that airwaves are simply unpredictable. There are unregulated broadcasts, illegal CB & radio boosters, solar flares, electrostatic energy, and other mysterious forces at work that sound engineers refer to as “ghosts.”