Audio gain staging!

"Uh?", I hear you utter in unison. It is though a pretty simple concept and crucial to a clear and un-distorted sound.

Gain staging simply refers to how you control the level at every stage of the sounds journey from mouth to finished article. If there is excessive gain at any stage of the process the audio will distort and fundamentally suffer, and it is not always obvious where this is happening. Phantom distortion can be an infuriating problem, so it is best to try and eliminate it from the outset.

Here is an analogy - I often think of audio processing as similar to water flow. Think of a water company supplying water to a neighborhood: water flows from the reservoir and goes through many series of pipes, if any of these pipes were to leak, or worse somehow contaminate the water, everything below that stage would be effected, and however well maintained and leak free the pipes further down the chain were, the water has already been affected. This is the same for audio, audio distortion and gain staging.

To stop it occurring I will list the potential places where it can happen, and if you do have audio distortion you can then systematically rule out each of these stages in your system, to discover whether gain staging is or isn't the problem for you.

- So to start with, it is important that the microphone itself isn't being overloaded, some microphones can take high SPL's (sound pressure levels), most dynamic microphones won't have this problem, and a lot of condenser, tube and ribbons are designed to withstand levels associated with the human voice. However some have such a sensitivity, that you need to be a certain distance or angle from them, and/or use some kind of pop shield or screen. More fully featured mics will have a pad switch which turns that sensitivity (level) down in multiple db increments. This is your first port of call when checking for distortion. I would take any other hardware out of the chain (compression/gating/EQ) when you check for this. and make sure your pre amp is relatively low, disable any plugins and processing, then turn your playback volume up to listen for any distortion.

- Next is to check your pre amp itself. Again disable any hardware or software dynamics or EQ, turn down the gain on your pre, and slowly increase it to a healthy level, use your meters on the pre and your DAW. Never go above -10db input level. If your pre has a line level or trim output you can also play with that and balance it with with the gain for a non distorted and healthy signal.

- Next is to check any hardware between your pre and the computer, check meters, LED's or however else the device is measuring level. If I personally compress on the way in, I never use more than -5db of compression and ensure a slow attack time to avoid chopping any transients. Check input and output levels of EQ units as this can be something that goes under the radar (remember that EQ itself is the process of increasing or decreasing gain, just at specific frequencies).

- Once your audio is in the system you need to check your input meters within your DAW, they should be WELL under 0db at your peak level on your master bus. Next, it is important to check the input and output of every plugin in your chain, on the channel, any sub buses and on the master bus, and of course the master output level meter.

If you don't hit the red at any of these stages, and you maintain a decent level throughout, you will not have any gain staging issues, and good for you!

I hope this is helpful to you!

Jamie

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