Guitarists and bassists: Untether yourself from your amp and pedalboard with a guitar wireless system! Instrument wireless systems replace the conventional instrument cable, allowing you to move freely around the stage (and the audience) without worrying about tripping over cables.
Every wireless system includes three main components: the input source, the wireless transmitter, and a wireless receiver. In the typical wireless guitar rig, the input source is, of course, your guitar or bass. Your instrument feeds an audio signal to the wireless transmitter, which is typically a battery-powered bodypack or beltpack about the size of a deck of playing cards (with a flexible antenna attached), clipped onto your guitar strap at the lower bout of your guitar. A short cable connects your guitar's 1/4" output jack to the bodypack transmitter's input, and the transmitter converts your guitar's audio signal to an FM radio signal, so it can be sent over the air to the wireless receiver. Magic!
Since the wireless transmitter is attached to the guitar or worn by the guitarist, it needs to be small, lightweight, unobtrusive, and tough enough to withstand your stage antics. Some guitar wireless systems employ a very compact "plug-on" transmitter which plugs directly into the guitar's output jack, eliminating the need for that short cable and bodypack. Another advantage of a plug-on transmitter: moving your transmitter from one guitar to another is as quick and easy as plugging in a cable, and there's no need to untangle the bodypack from your strap!
After the transmitter, the final key component of your wireless guitar rig is the wireless receiver, which receives the RF (radio frequency) signal from the transmitter, and outputs your audio signal that's ready for processing and amplification. The receiver unit can be mounted in your pedalboard, in your effects rack, on top of your amp, or at the mixing console. The most common type of wireless receivers are half-rack-sized units with an antenna or two sticking out from the back, but some wireless systems have receivers made specifically for guitarists and bassists that are designed to mount in a pedalboard, and can be powered by the pedalboard itself. If you use any effects pedals (or even just a tuner pedal) on stage, a "guitar pedal receiver" is a convenient choice for your wireless rig.
When shopping for a guitar wireless system, you'll encounter the age-old question: Analog or digital? Both have their merits. Analog wireless systems use time-tested radio technology to deliver high-quality audio with zero to negligible latency, since analog audio and radio frequency (RF) signals travel at the speed of light. However, analog does have one main drawback: all analog audio wireless systems use a compander circuit to overcome the limited dynamic range and higher noise floor inherent to radio signals.
The word "compander" is a contraction of "compressor" and "expander" -- which describes what happens to your audio signal in these wireless systems. For example, if your guitar's audio output has a dynamic range of 100 mm, and the FM radio signal that carries it only has 50 dB of dynamic range to work with, the signal must be compressed 2:1 on the transmitting end, then expanded 1:2 on the receiving end. This "companding" process works on the same principle as the noise-reduction technology that Dolby developed for analog tape recording and playback, half a century ago. While companding is relatively imperceptible in a good-quality analog wireless system, it can lead to audible artifacts like "pumping," "breathing," or a general "flattening" of dynamics that guitarists lovingly refer to as "tone suck." You may experience this when going wireless for the first time with a lower-quality analog wireless rig.
In a digital wireless system, there's no need for that compander circuit, because the analog audio is converted to to a digital signal that modulates the radio carrier signal in discrete steps -- ones and zeros. With digital modulation, your audio signal is unaffected by the RF link, since the wireless receiver only "hears" the ones and zeros. The result: Digital wireless systems deliver exceptionally clear, transparent audio, with broad, flat frequency response and greater dynamic range (which is great for guitar anad bass.)
Digital does have one very slight drawback: latency. Because digital wireless systems require an analog-to-digital conversion on the transmitter end, and a digital-to-analog conversion at the receiver end, they add latency -- or lag time -- to the signal. Latency refers to the delay, usually measured in milliseconds, between when an audio signal enters a system, and when it emerges. For example, most Bluetooth audio systems have noticeable latency. Digital latency isn't confined to wireless technology -- it's also familiar hurdle in the modern digital recording studio, where 32 milliseconds of latency is generally considered acceptable. Most high-quality digital wireless systems keep latency under 5 ms, which is completely unnoticeable to most players and listeners. Remember, sound travels at 332 meters per second, which means if you're standing 10 feet away from your stack, you're already hearing about 9 or 10 milliseconds of delay -- so another few milliseconds of latency from your digital wireless rig shouldn't be a problem!