Understanding Live Audio from a Rock Bands Perspective.

By: Paul Johansen.

The following article is intended in the main for musicians who have little or no experience of working with sound engineers and PA systems that are suitable for a full mic up with fold back and a front of house mix.

Very little has been written on this subject yet it is of great importance to those on either side of the mixing console. It is my hope to make a worthwhile contribution in this often confusing area and to unravel some of the mystery that surrounds the way sound engineers do things and the reasons they are necessary.

Often the way a band's participants would like to play and present themselves clashes head-on with the way an educated and responsible sound engineer would produce a show to the benefit of a paying audience. However this is unlikely to be the case if the musicians are experienced and mature.

The competent soundman should have the objective of reproducing a bands sound as faithfully as he knows how. In order to do this successfully he will need the full co-operation of the band itself. We have a quaint little saying in Pro Audio that goes like this: "Shit in, equals shit out"! In other words if the band insists in giving us a crappy sound then that is exactly what the audience is going to hear.

To explain things in a way that is easy to understand we need to take things step by step. When a band understands the fundamentals properly all things become possible. To appreciate this you need to understand that to get the best out of a PA system it needs to be used within its realistic operational parameters. This means it must be operated within a margin of 'headroom'.

Headroom in a PA system is the margin of available power left over when the system is running at the normal operating volume level. When a sound system is being pushed too hard there will be no headroom margin at all and this will result in severe distortion every time a loud note is produced. A band does not need to be loud on stage to produce a good result through a large PA rig; in fact quite the opposite is true. Sound men don't like really loud bands or at least that’s the way it should be because, as a rule, they know they will be against the odds getting them to sound good right from the beginning. To anyone but an idiot they mean big trouble. The big problem is all about what we call spill.

What Is Spill?

Spill is the sound that pours into a mic transducer from things other than that which it is placed in front of. Spill is the big enemy! We should all strive to keep it to a minimum. If we have six mics around a drum kit then all of these mics pick up sound from all over the stage and the reflected sound as well. They will of course pick up the drum kits sound louder because they are so close to the various items of the kit but nevertheless they will still pick up something from all the other items on the stage as well. It is just a question of how much. Spill also causes phase shift distortion. This occurs when sound is slightly delayed by distance and adds and cancels when it is picked up by the other mics.

Conduction. This is a problem that is less obvious than spill but can be just as annoying. It is caused by mechanical vibration from amplifiers sitting on a soft or loose stage floor flowing up the microphone stands. At its worse it can result in a single resonant frequency that dominates the entire performance. If the stage floor is not solid keeping the backline down in volume is the only solution.

If we were to consider the ideal situation there would be no back line gear on the stage at all and the band would be hearing themselves through the monitoring system. They would set their tonal sounds and effects etc using pre-amps. Here again in an ideal world the monitoring system would be an 'In Ear" monitoring system. No loudspeakers would be used on stage at all. When a lead guitar player with a 500 watt Marshall head unit and a huge quad box bowls up onto the stage the sound man is likely to be thinking, "Bloody hell here we go again". Things may actually be almost tolerable until he watches the power freak musician run his hands along the knobs and wind the whole thing flat out. For the sound man this is a recipe for disaster. He is effectively beaten before he even gets started. He can leave the guitarist completely out of the mix but he can’t overcome the spill. The spill is also what goes into the guitarist’s vocal mic that is placed directly in line with his instrument amplifier. Adding to the problem this changes as he moves from side to side exposing the mic more or less to the crescendo coming from the offending amp. It also spills into any other mic that is present on stage to varying degrees and it cannot easily be eliminated. Noise gates can be useful but they are tricky to set up well, take time to do so, and often don't do very much. The idea is to reduce this harmful effect by moderation and technique rather than deal with it later.

Loud guitar players are certainly not the only problem to plague the well-meaning sound engineer.

More often than not the problems begin with a hard-hitting acoustic drummer. The bass player, who usually stands alongside him, turns up so he can hear himself over the thunderous drum kit and the bass, which general spills everywhere, now pours into the drum mics and its all over rover. Everyone else in the band cranks up as well, so now we have a vicious circle. The bands don’t understand the resulting ramifications and so chaos is the only possible result. The sound man thinks, "These guys don't need a PA" and wants to walk out because he realises the audience is about to start blaming him for the lousy and hellishly overpowering sound that he is unable to control. The publican spits the dummy and the whole thing boils over into a hideous row. If you get the general drift of what I am trying to say here, lets discuss what can be done to address the various issues.

The stage cavity itself can sometimes act like a nasty little confining echo box that holds the sound in and makes it difficult to control. Everything is done in a tight little reflective space so spill can become a serious problem even when the instrument amps and the drummer are holding back. Every open mic channel is a spill collector whether we like it or not. The idea is to minimise it. The sound man likes to have the ability to control and balance all the instruments independently of each other. Things can turn to custard once he loses the ability to achieve this and it can be demoralising for him and musically destructive. Even if the PA is very powerful and overload is not an issue, spill can still ruin the overall sound quality.

As a contributing musician you need to get it into your head that if you are going to sound as good as you can to your beloved audience you must trust the sound man and fully co-operate with him so this can be achieved.

A guitar player can place his amp sideways if he needs to run it loud so that it is not facing directly into any microphones. It is far better to just turn it down. If you can't get the sound you want at a lower volume then experiment with various distortion pedals and equalisers until you can.

A bass player can play with a more trebly sound. In other words try going for more of a twang rather than a boom sound as this will greatly reduce the spill and clean the sound up tremendously. Turn your bass tone control anticlockwise and hit the strings closer to the bridge to achieve this. If you really want a boom sound then the sound engineer can do this at the mixing console whilst keeping it off the stage itself.

A drummer can use lighter sticks and learn to be more restrained. The best kits of all as far as the PA sound is concerned are the electronic ones as these have their own volume controls and produce no natural sound from the heads themselves. The drummer hears everything through headphones or the monitoring system so there is virtually no spill. Also they need no mics around them so they collect no spill either.

Rhythm guitarists and keyboard players are seldom a problem, but keeping the volume down still applies to them as well.

The muses in a band need to learn an attitude of empathy toward the sound engineer and see him as a very helpful associate and not someone who is there to make life difficult for them. Doing sound for a band that you don't know from Adam can is a daunting task especially if they decide not to co operates. Musicians who don’t like sound men may have either been the victim of a bad one or failed to understand the criteria when they were setting up or have heard another band sounding really bad. It may well have been that they were listening to an ignorant band who were hell bent on playing far too loud on stage.

The whole game is about subtlety. If you want to hear things loud it is far better to hear it from the fold back system because it produces far less spill than a backline amp does. This is because the wedges face in the opposite direction to the microphones. In ear systems produce no spill at all and are a wonderful contribution to the world of excellent sound quality. The problem is not many bands like them or trust them as yet although this would appear to be changing now.

The key as I say is understanding and if you want your band to sound really good to your audience then the quieter you are prepared to play on stage the better your music will be reproduced through the PA system. You need to learn to forget your ego and focus on the art of moderation fully aware that if the audience go away contented and impressed there is a good likely hood that they will be back for more and if you can achieve this then you may be well on your way to becoming a successful act. Think about it!

For any further information on this or any other blog topics please call Paul Johansen on Ph: 444 8776