Mixing for the Small Gig (Part 1)
How to understand those mixer type things that put all the noises through the PA. S'easy.
A beginner's guide. For those who've been faced with a mixing desk and wondered which button turns the coffee on Ben Duncan explains how you go from scratch to a workable mix.
GOING WAY beyond the accustomed four channels in the classic home studio, the array of knobs on the average stage sound mixer look, at first sight, quite a maze. But it's really no more than repetitious; if one channel has just nine controls, then 12 identical channels will total in excess of 100 controls.
Put another way, don't be daunted by the apparent complexity, since you have only to suss out the knobs and switches on one input, to grasp and use 80% of any mixer's capabilities.
With this simplification firmly in mind, we can now begin working through the typical channel (as portrayed nearby), imagining we're the sound engineer setting up for a sound check, and then actually mixing the gig. For brevity, this means we're assuming the mixer is all hooked up, and ready to go, and we're just climbing into the driving seat.
In any sound system, getting the levels right is the difference between an instrument that's audible and sounds good, and one that's shrouded in hiss, or else unpleasantly forward and distorted. Whether you're recording, or mixing live sound, the situation is much the same, except that for PA, anything shrouded in hiss simply won't be audible.
Setting levels on a console involves adjusting two separate controls, both of which set the gain, or volume. This task is made simple(r) once we recognise that the knob at the bottom, the FADER, is designed for moment-to-moment volume adjustments, while the (INPUT) GAIN knob, up the top of the channel, is a preset.
Later we'll be setting the fader in a position that's operationally useful: about ¾ of the way up is normal, or setting 7, or against the 0dB mark. If it's a knob instead of a fader, the equivalent position is 70% round the clock face, usually about the 2 o'clock position. Either way, this means there's a bit in hand (about 10dB, or a doubling in audible level), while leaving most of the control's range for tweaking the instruments' relative levels, and fading them out (hence the Bar is named FADER).
Before doing anything else, let's begin by (re)setting all the other controls to zero, or 'flat'. This means setting all EQ knobs, and the pan control to their central position, turning all the other knobs fully anti-clockwise, and taking all the faders to the bottom of their travel. The next stage is to start setting-up the levels, an instrument at a time, and without making any noise through the PA.
The secret is to don the cans (headphones) and switch the channel's signal through to the VU (or level) meters. Normally this is done by pressing a button or moving a toggle (lever) switch, marked P.F.L. (Standing for Pre Fader Listen, it's an ornate way of saying "let's meter it/hear it through the cans").
Next we'll ask one of the musicians to play something representative, so we can set the GAIN control. At this stage, it's useful to note that starting with channel 1, the instruments are generally connected in the following sequence: drum-kit (kit), bass, rhythm guitar (git), keyboards (key), sundry percussion, horns, etc, then backing vocals, lead guitar and finally, lead vocals (vox). What about the abbreviations in brackets? Commonly scribbled on a length of white gaffa tape stuck along the front of the console, they're vital for quickly identifying any channel in a hot situation.
Assuming the first muso summoned has now commenced playing, we can begin turning up the relevant channel's INPUT GAIN, while keeping an eye on the metering. If it's an ordinary V.U. meter (the 'swing-needle' variety), take the gain up until it's peaking around -6dB, which is a shade to the left of the red region. Because mechanical (cf. LED) meters are relatively sluggish, they can underread on percussion instruments and vocals, so don't be surprised if the sound subsequently distorts a fraction. If so, back off a little. If there's also an OVERLOAD LED, turn the gain up until it just begins to flash, then back off marginally.
If the metering tells us a particular signal is uncontrollably high (too 'hot'), try plugging into the mike or D.I. into the channel's LINE input socket. Alternatively, most mixers have a PAD switch nowadays, which knocks the level down, a step below the INPUT GAIN'S normal minimum setting. Otherwise, you'll have to insert a plug-in attenuator. Equally, we ought to check up on any players standing up: are they playing too close to their mike? Even if not, make sure they're aware of their positioning, since getting much closer during the gig can suddenly send levels soaring.
Once all the channel gains are set up, we can bring up the faders, have a listen through the PA, and begin setting the EQ. Again, this is best done one instrument at a time — keeping ALL the other faders shut down.
The imaginary channel layout nearby shows a 4 band EQ, meaning that we can adjust four different areas of the musical spectrum simultaneously, in the same way that a full-blown graphic equaliser can adjust eight or 27 areas of the spectrum. Many instruments can be satisfactorily EQ'd with just two (bass 'n' treble) or three (bass, middle 'n' treble) bands, viz. zones of tonal control. Even so, four bands are invaluable for one rather important component: the drum sound. That's because percussion abounds in low midrange sounds (which are soft, thunderous and 'muddy') and higher midrange sounds, which are harder and sharper, and the two need to be carefully balanced to avoid the drums sounding entirely muddy or too hard and 'bitey'.
Getting back to our soundcheck, if it proves difficult to get a good sound, it's a fair sign that the instrument's either miked up wrongly (try adjusting the mike's position), or you're using the wrong microphone anyway, in which case, try another. For example, a 'shrieky' vocals' mike won't bring out the kickdrum's or the bass player's thud, and if you only have a two band EQ, there's not much scope to compensate for this, making it all the more important that the bass instruments (say) are fitted-up with an appropriate mike.
Once a whole section — notably the drum kit — has been EQ'd, we can bring up all the relevant faders, hear it all in context, and get on with any fine tuning.
In Part 2, Ben Duncan gets into FX, panning, monitor sends, howl-round, and the routing buttons.
Feature by Ben Duncan
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