Buying Guide: Wireless Microphone Systems.
Table of Contents
- Types of Wireless Microphone Systems
- VHF and UHF
- Digital Wireless
- Wireless Microphone System Types by Application
- Instrument systems
- Handheld microphone systems
- Lavaliere microphone systems
- Headset microphone systems
- Clip-on horn mic systems
- A look at wireless microphone receivers and their features
- Diversity Circuitry
- Frequency Agility
- Automatic Frequency Selection
- Choosing a frequency
- Wireless Monitor Systems
- How much should you spend on a wireless microphone system?
Wireless systems have one obvious benefit—freedom of movement onstage, unencumbered by an instrument or microphone cable. For an energetic performer who uses movement as part of his or her performance, this can be an important advantage. This guide explains the types and features of wireless systems to help you make an informed choice of a system that meets your requirements.
VHF and UHF
All wireless systems operate on either VHF or UHF frequency bands. These terms will be familiar to most from their association with TV. VHF wireless systems generally operate within the 174 to 216MHz range (the range of TV channels 7-13), while UHF uses the 470 to 805MHz range (the range for TV channels 14-69). Traditionally, UHF has been used by higher-end wireless systems and has the reputation of having more transmitter range and less chance of TV interference. These are real advantages but need some qualification.
UHF is allowed more transmitter power by regulation, but that doesn’t mean that a system actually has more power. UHF also has more range than VHF, not from power, but because the signals move through the atmosphere more easily.
As for less interference, that situation is changing. As parts of the UHF range are being assigned to public safety communications, the band is becoming more crowded. Also, the highest end of the UHF spectrum (above 900MHz) is a general purpose range used for cordless telephones, garage door openers, and ham radio so is not advisable for wireless use as interference problems are very likely. Actually, both bands are becoming more crowded. Digital TV transmissions have recently been added to the BHF band, so though UHF is more crowded than it once was, it still has more open spaces than VHF and is the preferred band.
Digital wireless systems are relatively new and offer several significant advantages over conventional analog systems. The primary advantage is elimination of the need for companding and the signal degradation such processing causes. Digital transmission also avoids RF interference, and a system equipped with 24-digital converters will generally offfer a greater dynamic range than analog systems.
Instrument System: Instrument systems are usable with any electric instrument, but most often are used by guitar and bass players. These systems generally consist of a receiver and a bodypack transmitter which is connected to the instrument by a short cable. One system, the Guitarbug, has a small transmitter that plugs directly into a guitar output, thus eliminating the cable altogether.
Hand-held Microphone System: An ideal system for lead singers, handheld systems combine a receiver and a microphone with either a built-in transmitter, or a separate transmitter that plugs directly into the mic. With either type, there is no cable or bodypack transmitter. The advantage of the latter type is that you can use the system with your preferred microphone, rather than having to use the one that comes with the system. Some companies offer systems that incorporate popular microphone models.
Lavaliere Microphone System: Popular with presenters and in TV broadcasters, lavaliere systems are similar to instrument systems in that they employ a bodypack transmitter. A lavaliere clip-on mic connects to the transmitter via cable. Also, there are omni and cardioid lavaliere mics, the first being less directional than the latter.
Headset Microphone System: This is an ideal system for singers who want to keep their hands entirely free or for singer-instrumentalists who already have their hands full. The advantage is that the microphone, on a small boom and held in place by a headset, is constantly in position. You don’t have to worry about being "on your mic."
Clip-on Microphone System: Similar to a lavaliere, these are systems designed for use by brass and woodwind players. Each includes a receiver, bodypack transmitter, and a clip-on mic that attaches to the instrument. The big advantage of this kind of system is that the mic is always in the same position relative to the horn, in much the same way as the headset mic stays in position for a singer.
The true worth of a system is determined by its overall sound quality, dynamic range, freedom from dropouts and interference, and its distance range. Essentially, you want a wireless system to sound like a wired system. You want a system that has effective, easy-to-use controls and an easy-to-read display. There are a number of other common features that are not so immediately understandable.
Diversity is all about reception and freedom from dropouts, and most wireless brands tout it as a selling feature. One external sign of diversity is two antennas, although not all dual-antenna receivers have true diversity. Generally, diversity means that two antennas are monitored and the one receiving the strongest signal is automatically selected. This is effective because reception is in part a function of position and is influenced by the relative locations of the transmitter and receiver. By having two antennas, you reduce the chance of dropouts occurring.
Diversity circuits range from simple passive two-antenna systems, to systems that add antenna phase switching, to systems that actually use two receivers and select that output of the strongest. The most important question is: Do you need diversity in the first place? If your system is intended for use in a single location, and especially an open location such as a church, you likely don’t gain anything by having diversity. If you use a system in various locations that may have structures that block or deflect transmissions, diversity is more important.
This term refers to systems that have several frequency paths you can select from. This has to do partially with reception, because in any given location one frequency may work better than another and be clear of interference from competing signals. It is a feature that allows easier use of multiple wireless systems at the same time. If more than one band member is using a system, you need a choice of frequencies. If you plan to use a wireless system in just one location with no other systems operating, frequency agility is not so important.
Automatic Frequency Selection
With this feature, a frequency-agile system selects the frequency automatically. It’s a nice feature to have if you need a system with frequency agility as described in the prior paragraph, because you’ll be resetting your system fairly often.
Choosing a Frequency
When purchasing a system (especially one that is not frequency agile), you will be asked to select from several frequency options. These choices are designated by a combination of a letter and a number, but these designations are not standardized from one manufacturer to the next. Each manufacturer has its own system, but the letter usually designates a particular band range for the unit. The second part, the number, refers to a specific frequency within the range specified by the letter. You want to choose the letter that works best for your location, and a number that is different from other systems being used alongside yours. For the most part, the frequencies offered will work anywhere in the country and Music123 will, of course, help you make the right choice.
All wireless systems use companding circuitry and you often see the term used in system descriptions. The term combines "compression" and "expanding." There are different companding technologies and some are more sophisticated and effective than others. The transmitter compresses the signal and the receiver then expands it again. Companding is necessary because microphones and instruments have a greater dynamic range than transmitters are capable of handling. By compressing the signal at the front end, and then expanding it again at the receiver end, the dynamic range of the instrument or mic can be fully realized. Companding circuitry is also used in noise reduction systems and can give a wireless system a better signal-to-noise ratio and higher dynamic range. It all depends on the quality of the circuitry design.
Because systems from different manufacturers, or even different systems from the same manufacturer, have different methods of companding, you should avoid mixing components from different systems, even if they use the same frequency. Unpredictable results can occur.
As with any piece of electronic music gear, how well a wireless system keeps you informed of its status is an important consideration. Having a display that is lighted and large so it’s easy to read onstage is beneficial. It should tell you signal strength, identify the channel it is using, and a low-battery level warning indicator or battery level meter is important. These are usually located on the transmitter, but some high-end systems have the battery status indicator on the receiver.
The wireless monitor system uses essentially the same technology as the wireless microphone system, but turns it around. In this case, the central unit is the transmitter. It takes a monitor signal from the mixing board and sends it to a bodypack receiver that has ear buds connected to it. One benefit in this case isn’t freedom from wires, but freedom from having to transport bulky floor monitors that take up precious space onstage. The real benefit of a wireless system, however, is better monitoring. The ear pieces provide isolation from external sounds and are easier to hear than conventional monitors. Feedback is less of a problem and the monitor mix stays consistent when you move around onstage.
It all depends on your budget and your intended use. If you play professionally in a band that uses other wireless systems and plays in various venues, you probably want to spend more for a more advanced system. If you are playing in more casual situations and you’re the only one using wireless, a less-costly system will serve you adequately. We have broken down the systems into three price ranges, so you can conveniently check out the systems appropriate for your needs and budget.