The DJ mixer is what sits between the turntables or CD decks and controls the amount of sound from either source that hits the dance floor. A mixer also allows for queuing up of tracks into headphones or monitors, and can incorporate digital effects that can be added to the output. Even if a DJ is using a laptop to mix with software, that laptop will still be connected to the house mixer before it hits the sound system.
When learning how to DJ, it's important to be familiar with the different types of mixers that could be encountered at clubs and venues. While most mixers follow a fairly standard set up, there are some which can be a bit more confusing the first time they are used. Perhaps the most commonly found mixer style to in clubs and venues is that which is patterned after the Pioneer DJM-500. This mixer was one of the foundations of early club music, and it's tough construction and simple to understand interface have made it popular even to this day. Many other units have emulated its control layout and flow. The DJM-500 is a 4-channel mixer, meaning it can accept input from up to 4 different audio sources at a time. At the bottom and near the middle of the mixer is a crossfader, which moves laterally, allowing the DJ to mix between each sound source. The sources themselves also each have vertical faders which can control the level of the audio input. Every channel also bears 3 knobs which can affect the basic equalization of the sound, giving the DJ control over low, mid and high frequencies.
Throughout the years, Pioneer has added more features to their newer generations of mixers, giving some a digital interface which allows for the use of dozens of different effects, as well as enhanced visual monitoring of audio levels through LED indicators. However, the basic form and function of the mixer have remained the same.
Some companies, such as Gemini, and Allen and Heath, take a less traditional approach when it comes to the placement of mixing controls. Some of the Xone series mixers from Allen and Heath look considerably different than the traditional Pioneer, with the crossfader shunted off to one side and tracks laid out across the mixer's horizontal instead of vertical axis. While approaching these different types of mixers for the first time may be intimidating, the easiest way to acclimate to them is to locate the standard controls that are common to all mixers (faders, crossfaders, volume knobs), and then gradually work out from there to discover the extra or unique features of the device.
Mixers take a lot of abuse in the live environment, and when dirt gets into a mixer's sliders, it can interrupt the contacts necessary for proper audio transmission, resulting in a scratchy, crackling sound. It is important to always make sure to test out a mixer before it is used, in order to make sure it is in peak operating condition.
Khary Reynolds is a Pro Account Manager for Guitar Center Professional, specializing on sound system design. He is experienced in putting together sound and live sound systems from the ground up as well as music and pro audio product sales. Also a certified CTS by Infocomm International, the trade association for the A/V industry, Khary is dedicated to go above and beyond expectations, establishing himself as a respected resource. Visit his site, http://www.audiogearpro.com