Chapter 12

Letting Your Neighbours Know That You’re a DJ: Amplifiers

In This Chapter

Choosing the right amplification for your wallet and environment

Getting to grips with connecting it all up

Keeping the sound down to save your hearing and your neighbours’ sanity

Each stage of the DJ equipment chain is vital. Without the amplifier and speakers, you’ll be the only person to hear how good a DJ you are. In this chapter, I cover the various methods of amplification, the best way to connect and place your speakers, and how to play at a volume that won’t get you ejected from the neighbourhood.

Choosing Suitable Amplification

You need to choose a method of amplification that’s suitable for the size of room you’re playing in, and also for the size of your wallet – which are both important factors. The key word here is suitable. If you’re just in your bedroom practising at a moderate volume, you don’t have much need for a £3,000 1,000-watt amplifier and set of speakers, so save your money!

The different ways you can amplify the signal from the mixer so you can hear it through speakers are via:

• Your home stereo: For the bedroom DJ who has a good-sounding stereo with a spare input in which to plug the mixer.
• Powered speakers (the speakers have a built-in amplifier): If you don’t have a home stereo, or the one you have doesn’t have a spare input, powered speakers are perfect as an all-in-one solution.
• A separate amplifier and speakers: This combination is the best choice if you have a large room, hall or club that you need to fill with music.

Settling on your home stereo

Your home stereo (or hi-fi) is probably the easiest and cheapest route to go down when you’re just playing in the bedroom for practice, because you probably already own one. As long as you have a spare input channel on your hi-fi, and you can position the speakers close enough to your DJ setup so that you can get a good sound from them, your home stereo is a very good option. Although a hi-fi may not be as loud as a separate amplifier, if you’re playing in a modest-sized bedroom, it should be more than loud enough.

Don’t sneer at the idea of using your hi-fi. It can have great sound quality, produce very loud volumes and may have a built-in recorder to record your mix sessions.

If you get the chance to buy a new hi-fi on which to practise, search for one that has a manual graphic equaliser on it rather than relying on some nonsense settings for ‘hall’, ‘big hall’, ‘stadium’ and ‘bread bin’ to approximate the different sounds the music would make in those areas. A manual EQ (equaliser) lets you adjust the sound to your taste by controlling a range of different sound frequencies individually. If you plan to use the hi-fi to record your mix, full control of the sound is especially important. (See Chapter 19 for guidance on recording great sounding mixes.) Even if it means another £20, you won’t regret your choice. Hi-fis with pre-set EQs are great for domestic easy listening at home; but you’re a DJ – you’re far from domesticated.

The hi-fi also needs a spare input on the back in which to plug in your mixer. If you only have CD and phono inputs on the back, you have to use the CD input. (Phono inputs are only for direct connection of a turntable.) If you already have a CD player plugged into the hi-fi, you’ll need to unplug the CD player and plug in your mixer each time you want to use do some DJing, which can get tiresome. Instead, if buying a new hi-fi, try to pick one with a separate AUX (auxiliary) input to plug your mixer into.

The length of the cable between the hi-fi unit and the speakers can also affect your choice of purchase. For example, I have a Sony hi-fi with less than a metre’s worth of speaker cable between the base unit and each of the speakers. I have no plans to use it with my decks, but the length of cable provided is useless for DJ use, because I can’t get the speakers either side of the decks without needing to sit the base unit on top of my mixer!

Purchasing powered speakers

If you don’t have an amplifier or don’t want to tie up an input on your hi-fi with your mixer, powered speakers (also knows as active monitors) are a good alternative. Powered speakers are the same as normal speakers, except they don’t use a separate amplifier; the speakers have a built-in amplifier so you can connect the output of the mixer directly to them.

Consider power needs if using this kind of amplification. You may need to connect each speaker to its own power supply, or power both speakers from one unit. Make sure that wherever you intend to sit the speakers you have a power point close by.

If at all possible, to maintain audio quality, don’t cross the power cable over any of the audio cables, because this may cause electrical interference. You probably won’t have any problems if you do cross cables, but if you can get into the habit of properly laying the cables between two pieces of equipment now, you’ll know to keep the speaker cable away from power leads if you’re ever connecting a lot of speakers and amplifiers for a party or club night. The volumes involved at those events may reveal the electrical interference.

Powered speakers are very popular in the DJ booth as booth monitors. The volume control for this monitor is usually situated somewhere accessible on the side or back of the cabinet, which is perfect because you can turn it up or down whenever needed (especially if the mixer doesn’t have a separate booth-level control on it). Powered monitors in the DJ booth also don’t tie up an entire amplifier for the sake of one speaker, making good financial sense. See ‘Working with Monitors’, later in this chapter, for more about booth monitors.

For bedroom use, powered speakers can range in quality (and price) from basic computer monitors (often not the best sounding) to budget monitors such as those by M-Audio and Numark, which cost around £90 a pair and have an acceptable sound, to great-sounding powered speakers such as those made by KRK, Genelec, JBL and RCF, which can cost anywhere between £300 and £5,000 for a pair.

Opting for separates

A powerful amplifier with huge separate speakers can be overkill in the bedroom. Five hundred watts of music can sometimes be more than you need even in a large hall, so if you buy a high-rated amplifier and speakers and turn up the volume to full, don’t be surprised if your neighbours come knocking on the door!

Both the amplifier and the speaker have a power rating, which is measured in watts (abbreviated as W). The higher the number of watts, the louder you can play the music. Generally speaking, the rating on the back of your amp (short for amplifier) tells you the maximum sustained output that the amp can produce. On speakers, however, you may see two ratings: the average and the peak rating. The average rating (also known as RMS) refers to the maximum sustained output that your speakers can handle. The peak rating refers to how much power they can handle momentarily without risk of damage.

In non-techy talk, think about a trampoline. How low the membrane on a trampoline is to the ground when you’re standing still on it would be the average rating: it’s happy at this level, and nothing’s really going to go wrong with it. When you start jumping on the trampoline, as you land the membrane gets a lot closer to the ground momentarily. How close the membrane can get to the ground before suffering damage is the peak rating of your trampoline.

The peak value is always higher than the average value, and is why manufacturers like to print the peak in their documentation – it makes the speaker look more powerful.

When matching up an amplifier for use with your speakers, it’s safer to make sure that the power of the amplifier is less than the average rating of the speakers. No matter how loud the amp goes, it shouldn’t be able to blow the speaker this way. If you do want to choose an amp that’s more powerful than the average output of the speaker, make sure not to buy an amp that’s more powerful than the peak rating of the speaker. Even if you make a promise to yourself that you’ll never turn the amp up to ten, you can’t say the same for your friends or your drum-and-bass-loving cat.

Allowing a power margin for error

Choosing the power rating of the amps and speakers, especially when considering a lot of power for a hall or club setup, takes a little forethought and needs a margin for error.

If you’re looking to buy a setup that will give you 200 watts of power, the best option isn’t buying a 200-watt amplifier and speakers with an average rating of 200 watts, nor is it buying two 100-watt amplifiers to make up a total of 200 watts of sound.

The preferred way to set up this amount of power is to buy three amplifiers and three sets of speakers, and run them all at two-thirds of their output level. Running two amplifiers at full volume for too long is running the risk of one, or both, breaking down – but three amps at two-thirds of their power will run happily for a long time. And even if one of them does blow, you’ll still only lose one-third of the power instead of all or half of the power in the other two examples.

Table 12-1 is a general guide to the room size, occupancy and power rating you may need for different situations. This guide isn’t a set-in-stone rule, and you may want more than suggested to give you a little ‘headroom’ of power, in case you want to go louder.

Table 12-1 Amplifier Power Needed for Different Room Sizes

You may have noticed that the number of people in the room affects the amount of power you need. People are very greedy. Not only do they raid your fridge for beer and food, but their bodies also absorb sound waves, robbing some of the volume from the room. The more people that turn up, the louder you have to play the music to be heard at the same volume! The good thing is that even though you have to turn up the sound a bit, as the stray sound waves are soaked up by the crowd this can improve the sound on the dance floor.

As well as counting the people on the dance floor, when you’re choosing the amount of amplification for an event, take a look at what’s around you; the decor and the floor are just as important as the size and capacity of the room. A room with wooden floors and wooden or mirrored walls bounces sound waves around the room, making the music sound a lot louder. A room with carpet flooring that has big, thick curtains in it does just the opposite, absorbing a lot of the sound waves – so you may need a touch more power. And if you’re DJing in the open air you’ll need a lot more power, because all the sound waves disperse into the air rather than bouncing around a room.

On top of all the power mentioned above, add in a sub-woofer. You can’t get a good sound on the floor without one. Most of the frequencies lost to the furniture or flesh in the room are the bass frequencies; keep it healthy with a low frequency sub-woofer.

If you want to know how to connect multiple sets of speakers into your amplifiers (which is essential knowledge for club systems and some mobile DJs), check out the DJing page on the For Dummies website.

Working with Monitors

Your booth monitor is your link to what’s really happening on the dance floor, and can make the difference to your night going well or going to you know where. Without hearing the exact audio that’s coming from the mixer at the exact moment it comes from the mixer, you’ll have a really hard time beatmatching. In the bedroom, the ‘dance floor’ sound and the music you hear in the ‘monitor’ are the same thing (usually because they are the same thing), but in a club, the two sounds are a bit different.

The booth monitor is easy to take for granted. You don’t miss it until you don’t have it any more. It not only lets you gauge how the music sounds playing to the dance floor, but also helps with the accuracy of your beatmatching.

Working with the speed of sound

The speakers on the dance floor are probably only 10 to 20 metres away from the DJ booth, and they’re sure to be loud enough for you to hear them. But volume doesn’t have much to do with how long the sound takes to get from the mixer to the speakers and then to your ears. The speed of sound is 330 metres per second. If the speakers are 20 metres away, the sound takes around 1/16th of a second to get to you. In music, this fraction of a second is an extraordinarily long time, and although it seems like a tiny delay, the delay is enough to throw your beatmatching out of time and make you sound like a complete amateur.

This is where the DJ booth monitor comes in. The monitor is often a pair of speakers either side of the DJ, but in some cases is just a single speaker positioned to the left or right of the DJ. A monitor right next to your ears cuts the audio delay from 1/16th of a second to 1/256th of a second (if it’s a metre away), which is more than acceptable.

Positioning your monitor

Unless you live in a mansion, you’re unlikely to have to deal with any delay in the bedroom from your speakers to where you have your decks set up. If you do practise in an oversized room that’s causing a delay similar to working in a club, ask your butler to bring one of the speakers closer to you. Sarcasm aside, if bringing a speaker closer to you isn’t an option, then you can hook up a separate booth monitor (maybe a powered speaker) to play right next to your DJ setup, or you can add another pair of speakers to your existing setup and place them next to your homemade DJ booth.

The monitor needs to be close enough to counteract any delay from the dance floor but also overpower any music from the dance floor that you may still hear in the DJ booth. Keeping the speaker close and facing you gives you the best clarity. Too far away and you may find it harder to pick out a solid bass thump or the crisp hi-hats and snare drum that you use as reference when beatmatching (see Chapter 14).

The perfect position for a monitor in the DJ booth is 1 to 2 metres from the mixer, slightly in front of you, at head height and with the speaker turned in to point directly at you. Assuming that your speaker has the bass driver (the big speaker) at the bottom and the tweeter (which plays the high frequencies) at the top, this position is perfect for getting the best sound quality from your monitor.

If the monitor is too high, the bass driver dominates the tweeter, drowning out a lot of the high frequencies from the music. If the monitor is too low, aimed at your waist, the bass is lost, leaving a shrill, unclear sound dominated by the high-frequency tweeter that’s at head height. Turning the monitor on its side so both the tweeter and bass driver are at the same height helps to prevent either eventuality.

For your bedroom setup, you may not have much room or much control over where you can put the speakers. The two things to keep the same as in the club DJ booth are that the speakers are in front of you and pointing toward your ears, and that you try not to set the speakers on the same piece of furniture that your decks are on. If the vibrations from the speaker cause the turntable to vibrate, you’ll generate feedback. If you’re using CDs, you may cause the CD player to skip with the bass vibrations.

Digital DJs using controllers with computer software should be a little better off than the vinyl or CD DJ when it comes to speaker vibration. But you don’t want vibrations to cause problems with reading the hard drive.

Noise Pollution: Keeping an Ear on Volume Levels

Many reasons come to mind as to why you shouldn’t play your music loud all the time, but hearing damage (which I cover in Chapter 11), neighbour relations and the quality of your mixes are paramount.

Protecting your ears

Keeping the volume of your monitor at the lowest functional level protects your ears and reduces any risk of distortion from the headphones or the monitor.

One of the most popular ways to cue up the next tune (get it ready to play) and match the bass beats of two records is to use a technique called single-ear monitoring. This technique is when you have one ear open to the music from the monitor playing the live sound from the amplifier, and one of the headphone cups on the other ear, listening to the cued song that you want to play next. (For more information on this, check out Chapter 14.)

To help with the accuracy of your beatmatching when single-ear monitoring, you only have to play the monitor loud enough to drown out the music from the dance floor. The trick is to match the volume playing in your headphone ear to the volume from the monitor in the DJ booth. Due to the proximity of the headphone on your ear, this is about perceived volume rather than trying to match the actual decibel level coming from the monitor in the DJ booth, because to do so would make you go deaf.

Keeping everything at as sensible a level as possible not only helps to delay hearing loss, but also prevents your ears from getting fatigued through the night as they’re blasted by sound. The louder the music, the quicker your brain will start to tire, and you’ll start to lose the subtleties in the music that help you in the mix – like hearing the beats go out of time before anyone else does!

Neighbourhood watch

Keeping the music at a sensible level to aid your mixing and protect your hearing are both important, but you also have your sense of social responsibility to think of. Not only may the rest of the people in your flat, house or building start to get a little irked when you play pounding bass beats at full volume for hours at a time, but the people in surrounding buildings may soon get fed up with the dull thudding noise coming from your house.

Realising that you only need one speaker

When you’re DJing at home, you really only need the one speaker, and that’s the one you use for the ‘live ear’ when using single-ear monitoring to beatmatch (your equivalent of a DJ booth monitor).

When a neighbour pointed out how annoying the bass of my sub-woofer was, I put switches on all of my speakers so I was able to leave only the monitor speaker running. This meant that I could play the music just as loud as before; because only one speaker was playing, the volume that other people could hear was a lot lower, yet the volume that I perceived from the monitor stayed the same. Turning off the unnecessary sub-woofer helped a lot, too!

If you only have two speakers, you may not need to add switches to isolate one speaker. If your amplifier (or hi-fi) has a balance control, just pan the music so that it only plays out of your preferred speaker. (Although, if you use a hi-fi to record your mixes, this may result in the recording only playing out of one speaker too.)

If you’re thinking of adding switches to isolate your speakers, do some research into the best switch to use. I must admit I used light switches at first, but they’re not designed for audio signals and can add too much resistance to the signal from the amplifier to the speaker, even when the signal is just passing through the circuit. This resistance may only cause a drop in sound quality or volume, but in the worst case it may break your amplifier. Something as simple as the Hama LSP-204 (shown in Figure 12-1) can do the job a lot better for up to 100 watts of sound.