Image Courtesy of: Cristina Mosol

The size of a venue plays an important role in the type of sound system that should be installed. Whether the system is to be used for live performances by bands, singers or stand up comedians, or whether it will see duty playing dance music or hip hop, choosing the correct size and type of speakers to be installed is largely a function of the dimensions and character of the room itself. It is all too common to enter into a venue where little thought has been put into this aspect of equipment purchasing, and the loudest system that the owner could afford was installed without any concern as to how it might actually overpower the room. This leads to muddy, unintelligible sound that no one will want to listen to for an extended period of time.

The key to proper speaker size selection is to realize that, especially when it comes to bass sounds, the volume of air in a room plays an important role in how large a speaker has to be in order to be properly heard. It is natural to think that in a large venue such as a concert hall or an exhibition center, a bigger speaker will be heard better because it must push sound waves through a larger volume of air. Since sound waves are essentially air pressure waves, the more distant a listener is from the source, the fainter that sound will be.

However, it does not follow that a larger speaker will also sound well in a smaller space. There are several reasons for this. One is that air is not the medium which can transmit sound. Pressure waves can also move through floors, ceilings and walls, especially low frequency sounds such as those produced by woofers and sub-woofers. If a large enough speaker is placed in a small enough space, then the intensity of these pressure waves will vibrate the materials of the room so much that they begin to emit sounds themselves – extremely unpleasant sounds. This is on top of the rattling that is caused by the movement of these materials and anything that is attached to them. On top of that, the powerful pressure waves will not have enough space to decay naturally, and instead will bounce from surface to surface, creating standing waves of sound which accentuate certain frequencies and cancel out others. This all combines to create a soupy musical mess.

It is obviously important that speakers be sized to match the size of the room in question. However, a final point to remember is that an empty room will behave much differently than one filled with people. Since a gathering of human bodies will act to absorb a significant amount of sound energy, then a speaker system must be large enough so that it does not have its volume negatively affected by this absorption. It can be a delicate balance to accurately gauge how large a speaker must be to fill a packed room, yet still not overpower the acoustical properties of the venue.

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The DJ mixer is what sits between the turntables or CD decks (just in case you didn’t know) and controls the amount of sound from either source that hits the dance floor. A mixer also allows for cueing 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 its 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.

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In my experience with DJs over the years, there seems to be differences in philosophies in DJ equipment and deciding what format play. As it stands right now, there are three primary forms of media used in professional DJing today.

#1 – Vinyl

Also known as records, wax, or LP’s, vinyl is a holdover from the glory days of DJ culture, when the hottest tracks were only available as fresh pressings from underground record labels. While time has moved on, and LP’s are no longer the currency in trade of the popular music industry, the genres of electronic music and hip hop have both kept the format alive. Many major labels and smaller imprints still release brand new music on wax.

The weapon of choice for vinyl DJ’s is the Technics 1200 series of turntables. First introduced in the 1970’s, the 1200’s have built up an enormous following over the ensuing decades. While the model has been updated several times in order to tweak certain features or create special models, it has remained largely unchanged, and it is not unusual to encounter 20 year old 1200’s still pulling active club duty.

#2 – CD-R or CD’s

CD technology has also made significant in-roads when it comes to DJ culture. At first, CD-DJ’s or CDJ’s (the devices used by DJ’s to play CD’s) were seen by vinyl purists as being ‘too easy’, or somehow a shortcut that allowed people to DJ without learning any of the same skills that vinyl DJ’s had to apprentice.

While it still has its detractors, CD DJing is much more accepted nowadays than it used to be, partly because old school DJ’s began to appreciate the skill required to properly manipulate CDJ decks, and partly because CD’s are much smaller and have better durability which made it a much more transportable technology – a very appealing characteristic to the gigging DJ’s. One of the more popular companies in the field when it comes to CDJ’s is Pioneer, although they have some competition from Denon and a host of other companies such as Gemini and Technics.

#3 - MP3’s

MP3’s are the most recent and most controversial format when it comes to DJing. MP3’s are compressed digital music files which can be easily shared and transmitted over the internet, on burned DVD’s or CD’s, or on flash drives. When it comes to playing them at a club, a laptop with specific software is usually the method of choice.

Rane’s Serato Scratch Live and Traktor are two of the most popular programs used to DJ with this audio format. Those who use MP3’s face a lot of criticism in the DJ community for a number of reasons. Some people claim that the use of MP3’s is an endorsement of music piracy, since there is no practical way to verify that a DJ paid to buy the tracks they are playing. This same complaint was made regarding CD DJ’s who burned their own CD’s, and seems to be the rallying cry of those with a heavy investment in vinyl.

There are also those who say that the compressed audio of this file format does not adequately capture the necessary musical frequencies in order to sound good on a large sound system. With the use of higher bit rates, this problem can be largely alleviated. Finally, another frequent complaint is that the use of DJ software removes any vestiges of skill from a DJ’s performance, as many programs are capable of automatically beat-matching tracks.

Although each of these three formats have their champions, it is safe to say that MP3 technology is showing no signs of fading. With the advent of low-cost laptop computers, more and more people are becoming interested in this most portable form of DJing.

CD DJing will likely remain popular, due to the number of clubs which are set up for this type of performance, but vinyl DJing is becoming an increasingly rare skill. With more clubs converting to digital systems and fewer new DJ’s willing to purchase large amounts of expensive vinyl; it will likely remain a niche in the DJ world.