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How does a mixing console work?
What is signal flow?
Learn how to read a signal flow diagram.
We’ve all been there at some point. We’ve all stood in front of a mixing console in a studio and wondered ‘how the heck does this work?’.
It’s easy to feel overwhelmed when faced with routing your signal through a mixing console but the reality is it’s a fairly easy process that can be translated from one desk to another.
A very simplified way of understanding a mixing desk is to compare it to your interface at home. You’ll have your option to increase or decrease gain, phantom power and line/mic inputs. The consoles you see in a typical studio are essentially larger versions of this.
It’s once you start implementing a desk into your workflow that it can start to become a little more complicated.
To make things easier for you, we’re tackling the basics of mixing console signal flow.
The Function Of A Mixing Console
A mixing console allows you to feed your recorded signal into your DAW and then monitor the sound as a full mix via the console faders.
Nothing is actually recorded onto the console.
After setting your gain levels you will usually find an EQ section on the desk which will allow you to sculpt your sound before hitting the DAW and sometimes you’ll even be able to add a touch of compression via the console.
After the signal reaches your computer it will feed through your DAW channel (and it’s plugins) and then back out to the desk where you can lower or raise the volume on the channel faders.
Breaking Down The Signal Path
So we know generally what the function of a mixing console is now, so let’s break it down into more details and understand what happens to the signal as it travels from its source to monitoring.
You will first need to tell the console whether you are recording from a microphone source or a line (such as a keyboard or synthesiser). The reason being mic signals are a lot weaker than line so to ensure proper gain staging you need to set the desk up to receive the appropriate feed. If mic is selected then your signal will be input to the desk preamp, whereas line will usually skip this section as extra gain isn’t necessary.
If you are using a condenser microphone you will need to enable phantom power, which sends a small electrical signal to the microphone, essentially turning it on. Always double check however as not all mics will require phantom power and can be damaged by accidentally turning it on.
Next you need to set the correct gain level. Gain staging is crucial to getting a clean signal and ensuring you have an adequate signal to noise ratio. You’ll also usually have a Pad option which enables you to lower the signal by a certain amount of dB if it is too loud (for example if your microphone is particularly sensitive and your singer is particularly loud).
If ‘mic’ is selected then the signal will route to the desk preamp. As mentioned before, microphone signals tend to be quite weak, so a preamp is needed to increase the gain of the signal to a recordable level. Often producers will use external preamps depending on their taste, rather than the desk preamp, which can be inserted into the signal chain via a patch bay.
You’ll usually see an option to reverse the phase of your signal. Essentially this flips the waveform of your signal upside down, so the positive oscillations are now negative and vice versa. This is crucial to check when using multiple microphones as if one or more are out of phase (i.e. when one is positive the other is negative) then you can end losing the low end in the affected tracks and sometimes the whole signal itself.
An insert will usually lie between the preamp and EQ section of the desk. It allows you to place an effects unit or signal processor (such as a compressor) into the signal chain. You would need to physically route this out of the insert, into your effect and then back into the signal chain. This is often done via a patch bay or through points on the channel strip in smaller mixers.
You will usually find an EQ section on your desk which allows you to tweak the frequency content of your signal. The EQ on a mixing console isn’t as effective at targeting specific frequencies as a graphic EQ or a plug in but they are great for making adjustments during the recording process. Some EQ’s can either be set to affect the signal before it hits your DAW or after (at the monitoring stage).
A mixing console usually has a selection of auxiliary sends on each channel. If you’ve mixed in the box before, then think of these as like a bus channel. An aux allows the desk to send an identical signal from the channel to another destination. This could be to utilize an outboard effects unit or even to simply create a copy of the original track to parallel compress. An auxiliary send will often have the option of ‘pre’ or ‘post’ send, which gives you the option to send the signal before or after your faders. Pre means that you can adjust your fader as much as you like in the control room, but this won’t affect the level of the auxiliary whereas post will do the opposite and will be affected by your faders.
This stands for ‘pre-fader listen’ and gives you the opportunity to audition the track before it hits the channel fader.
After all the above your signal will hit your DAW, which is where you will physically record the track. This won’t need much explanation, but it is worth remembering that tweaking any of the above parameters (such as gain, phase reversal) won’t affect the signal once recorded, so you’ll need to ensure your settings are perfect before starting to track.
Once the signal leaves your DAW it will hit the panning stage. A simple dial enables you to pan your signal left or right to the desired amount.
This function simply mutes the signal from that particular channel. You may use this for example if you want to cut out your bass channel so you can just listen to the drums without having to adjust your fader level and lose the ‘sweet spot’.
Again a very simple function, a solo button simply removes all but your solo’d channel(s) from the mix.
These are last in the chain and again, are pretty self-explanatory. Use your faders to increase or decrease the volume of the track you are listening to. Remember however that your faders and panning come AFTER your DAW, so any changes made on these will simply be for monitoring purposes and won’t be hard printed into your recorded signal.
Master Fader – The last thing on your desk will be your master fader, this controls the whole volume of the desk after the individual track faders. If you aren’t hearing any sound, it may be that this is turned to zero. If this happens, be cool and try and turn it back up without anyone noticing your error!
For example, when creating a headphone mix, a drummer will usually want a fair amount of click track in their headphones to keep in time. However, in the control room, you may be more interested in hearing how the drums feel overall, and so want to hear less click.
Setting your headphone mix to pre-fader allows the signal to be sent before the actual channel fader (at the monitoring stage). This allows you to raise or lower the volume in the control room without affecting the drummer’s headphone mix.
It can be daunting the first time you get your hands on a mixing console. However, getting to grips with its layout before a session can really help, whether that be downloading the manual or just looking at pictures online.
If you find you aren’t getting a signal at any point, just retrace your steps and make sure everything is as it should be, often problems can be attributed to a switch being off or a fader being down!
Once you start to understand the way a signal flows through a mixing console, you’ll easily be able to translate this knowledge to other desks which will make your workflow (and diagnosing any issues) a lot quicker, but more importantly more fun.