What's With All Those Knobs? A Primer on Mixing Boards
By Ben BlakesleyGeorges Music
Working as a recording (and sometimes live sound) engineer, I get a lot of clever comments about how complicated the gear looks. Really, that's one of the fun parts about being an engineer. You're a part of an exclusive club of people who know what all those lights, knobs, and meters actually do!Well, WELCOME TO THE CLUB my friend. Allow me to let you in on the secret...
The Channel Strip
Every mixer is going to be slightly different, but all mixers will share a few core elements. To make this manageable, here is:The Engineer's Secret
- Most of the knobs do the same thing.Of course what I mean by that is that a mixing board is comprised of what we call Channel Strips. A Channel Strip [see picture] is a vertical column of knobs (and faders and buttons) that affect 1 track or 1 input on the mixing board. For instance, if you have a guitar plugged in to Channel 1, all those knobs on channel 1 will only affect the guitar track.Mixers will vary in their track counts from 4 all the way up to 192 for large format consoles. And that's what I mean by 'most of the knobs do the same thing.' Each individual knob on a mixing board isn't entirely unique, but rather there are multiple channel strips that have the same number of knobs with the same functions.So essentially, on a 12-channel mixer we've just cut the number of knobs we need to learn about by 91.6%!!So let's start at the top:
- this is where you'll plug in your microphone. (I know, very insightful!!)1/4" Line Input
- This is where you would plug in a keyboard, guitar/bass, or other source that is not picked up with a microphone. (Note: for guitar and bass, it's better to use a Direct Box and plug into the XLR input. I won't go into it here, just trust me).1/4" Insert -
This is where you would put an effect into the chain. For instance, if you had a compressor that you love on vocals, you would use a Y-cable to put it in line here. This 1/4" jack will typically accept a TRS input (tip, ring, sleeve. It looks like a stereo cable) and it will use one wire as the send and one wire as the return. The other ends of the cable go into the input and output of your effect uint.Gain Control
- Very important. This is where you dial in a healthy signal for your source. It's important that you set this correctly as it will make a difference in the quality of the sound you get for this track. You want to set this so your meters are showing a strong signal when the source is being played, but not to the point where it's clipping or distorting. DO NOT USE THIS TO CONTROL THE TRACK'S VOLUME![This particular unit, the Yamaha MG124CX
, has a Compression knob next, but that is not typical]EQ
- This is usually more than one knob. In this case, we have a High band, Mid band, and Low band. Use this to sculpt your sound and make it more pleasant or fit in the mix better. It does just what it says, increases/decreases the high, mid, or low frequencies by the amount you turn. If your track lacks sparkle, you'd increase the High band. Too boomy? Cut the low frequencies. Need some clarity? The Mid band is your friend.Some mixing boards will have an additional knob for the Mid band. This is called 'sweepable mids' meaning that you can control the center of the frequency being boosted or cut.Aux Send
- This is similar to the Insert function we talked about earlier except that Aux sends can be used for multiple tracks. The actual Aux Send/Return input/output will be located elsewhere on the mixing board. This knob determines how much of this track's signal is going to be sent to that external device. This will typically be used for a reverb/delay type of effect, or to create a separate monitor mix for the musicians.[This particular unit, the Yamaha MG124CX
, has an Effect knob next, but that is not typical. It will appear on any mixer that has built-in effects and refers to how much of the selected effect should be applied to the track.]Pan Control
- This knob sets the spatial position of the track in the stereo field. If you turn it counter clockwise, you'll be moving the sound to the left and vice versa.Mute
- Typically this button is called Mute and does just that! When pressed, it cuts that track from going to the main output.Fader/Volume Control - Use this slider to determine how loud the sound on that track will be.
That's it!See? It's not so hard is it? Now just duplicate that for each track and you've got a collection of knobs to impress all your friends. Next time they ask, "You know what ALL those knobs do?" You can smile and answer, "Yes!"
Ben Blakesley is in charge of Marketing and Technology at George's Music and plays with knobs and faders as the Chief Engineer for Javboy Records.