Gain Staging for Dummies

maxresdefault.jpg

Gain staging defines the process of managing audio levels a each step of the audio signal flow; which prevents distortion and noise in the signal which can be introduced with poor gain staging.

In any system containing an input (i.e. microphone/instrument) and an output; the aggregate amount of gain can go beyond 100 dB which is broken down into few smaller stages where the audio is boosted or reduced before reaching the outputs.

It is important to know that the ideal point of gain staging is where each audio part in the signal sends and receives signal in an optimum region of its own dynamic range.

Microphone Placement


Let’s start our signal flow with a sound source (i.e. instrument or a vocal); our microphone preamp is the first gain stage that we could adjust; at this point microphone placement is the most important part as the inverse square law dictates that moving the microphones closer to your sound source will increase the signal produced by the microphone and vice versa.

Fig1.gif

From the point onward; following the preamp- the signal has been brought to +4 dBu and can accept further processing.

Peak Meters vs. RMS Meters.

We’ve discussed this before; however it’s good to recap.

4_io_rms_peak.png

Peak level is not as constant as average level, transients can be sometimes high and others low. Peak meters will follow those instants, which is always good to monitor high transient signals or to capture the highest level of a signal no matter how brief.

Note that sending the same signal to a Peak Meter and an RMS Meter will not result in an identical decibel reading on both meters.

Headroom and linearity in digital audio

Unlike analog medium; you don’t need to record at extremely high which was a common practice to combat noise being added by the hardware involved in the recording process.

When you push preamp close to 0 dBFS, you’re compromising your headroom which results in the loss of definition in your mix.

Tip: It is always good practice to leave enough head room for the mastering stage.

Each recording medium has a limited or a finite amount of headroom and when you push the recording signal more than what the medium is able to handle, it clips and you’ll hear distortion.

One of the issues that is taken care of in digital audio is noise floor, in DAWs the system noise is very low and doesn’t impact the recorded signal.

Unity Gain

The term unity gain is essentially when an audio signal passes through a piece of gear and the output is the same when that piece of gear is on bypass.

Establishing this will give you a much cleaner signal, clear of distortion or feedback

Unity-Gain1.gif

Floating Point processing allows for extreme gain staging without the danger of clipping distortion or the loss of bits. Provided your levels do not go beyond 0 dBFS at an input or an output of a discrete floating point; then DSP chip extremely high and low level signals can be tolerated without any negative impact on quality.

Output gain

The max out is equal or more than the signal level required to drive your amp to full output power.

If using an active speaker, it’s recommended to consider each driver, as each one might have different sensitivity.

To Recap

If it was done right, then you shouldn’t worry about clipping; make sure you take your time managing your headroom and gain staging.

Ahmed GelbyComment