Monitor Systems Overview
The monitors are one of the most important parts of a PA system. Those with a good level of experience understand the value of good monitors. Basically, if you have good monitors you will have a good show. Some with less experience don't realize this. When assembling their PA system they tend to be concerned with enhancements to their front of house mixing equipment. While the toys are nice to have they won't make as much difference as good monitors will make to the show. Having weak monitors or inadequate power can often lead to more feedback problems.
Musicians need to be able to hear themselves and other musicians in order to play their best. All musicians need to be able to hear the timing cues. Singers need to hear their voice and may need to hear some melody instruments for pitch. If vocal harmonies are a part of the show the singers need to be able to hear the other singers as well. For timing musicians must be able to hear what ever they cue on for their time, be that snare, high hat or something else. If there are multiple guitar players, particularly if they are doing guitar harmonies, they may need to hear the other guitar parts.
The basic parts of monitor system are the signal source which is fed usually through an EQ to the power amp which then drives the speakers. In smaller PA system the signal source is generally an aux send on the mixing board. This is then fed through a graphic or parametric EQ to the monitor amplifier. If the output device is a speaker system it is typically in the wedge format. On bigger stages there may also be side fill stacks. Often the drummers monitor is a little beefier than a standard wedge.
Monitors are run either from an auxiliary send or sends on the house console or, for larger stages, are run from a dedicated monitor console. The practice of running monitors from the house console is less than ideal. Running monitors from a dedicated console allows the front of house technician more freedom and the musicians are more likely to be able to hear what they need to hear. Typically, with a dedicated monitor console there is a monitor tech on stage. This allows good communication with the musicians.
A multi-mix monitor system allows the musician to hear exactly what they need to hear. With a dedicated mix it is not necessary to have everything that someone else might need in the monitors blanketing the stage. This can allow for an overall reduction in stage volume. Properly used each musician can hear what he needs for timing and pitch.
The earliest form of monitors were simply additional speakers pointed back at this stage. These helped but did not do exactly what the musicians needed. The floor wedge driven by a separate monitor amplifer improved the situation and multi-mix monitors were another improvement. Concert wedges are typically bi-amplified with an electronic crossover to separate the low and high frequencies. Self-powered monitors are now available that eliminate the need for a separate monitor amplifier. These often are bi-amped and contain tailored signal processing that can reduce the need for outboard equalizers (usually a graphic Eq is still used for feedback suppression).
The most recent improvement in monitor systems are the personal in-ear monitors. In-ear monitors eliminate the problem of added stage volume that traditional monitors impose. There are wireless systems for those that need freedom to move but wired systems are less expensive and can usually be used by keyboard players and drummers. Some wired boxes have 'more me' controls that allow a generic mix to be sent to the box but run the mic and instrument signals through the box allowing separate control to the user.
In-ear monitors, when properly used, give the musician some hearing protection. The ear-buds used in the best in-ear systems are fitted to the musicians ear. They are quite effective at isolating the musician's ears from high stage volume. Because of this isolation they can allow the musician to hear everything that he needs to hear and still maintain a lower volume to the ear.