Gain Staging using VU Meters
What are VU Meters, how do they work and how to calibrate them for mixing.
Gain staging is actually quite a simple process to understand but complicated to administer. In modern mixes we are presented with high track counts which cause all manner of gain issues. Not only do we need to manage the gains of all the audio stems but we need to account for channel effects and certain dynamics that are run on their own channels. Add to that instruments, microphones, pre amps and so on and you can quickly see why things can get out of hand and your mix ends up clipping.
Headroom is the difference between an audio tracks peak level (when the meter is displaying its highest value) and 0 level (ceiling) on the output meter. Let me give you a simple analogy I always use to explain headroom to my students. You are 6 feet tall and you enter a room that is 10 feet high. You have 4 feet of headroom. I know it’s simplistic but it works for me.
In digital audio we are concerned with two values: the noise floor which is the lowest or quietest value, and the ceiling which is 0. This difference between the noise floor and ceiling is what we refer to as dynamic range. In layman’s terms think of this as being the difference between the quietest and loudest part of an audio signal.
Gain staging involves optimising the audio signal through each and every process whilst maintaining ample headroom and a healthy signal to noise ratio, all the way from external hardware to the final stereo mixbus. We achieve this by managing the relative gains of every process and sound and making sure not to exceed the ceiling.
Now that we understand what gain staging is let us look at an example that involves using VU meters for gain staging. It requires a slightly different mindset to the usual PPM gain structuring tasks.
VU meters are the closest meters that behave like our logarithmic hearing. They show only relative levels and have a slow response time which makes then a little restricted in terms of the information given to the user. Additionally, vu meters have to be calibrated to the system known reference level. In most digital systems when using a vu meter we tend to calibrate to -18 dBFS (decibels full scale). We use dBvu as the units of measurement for vu meters.
Once we have calibrated the vu meter we can use it as the target reference for each and every gain stage process.
In the video I explain how vu meters work, how to calibrate them to a reference and how best to use metering targets for the gain staging process. I make sure to explain the metering standards and how to customise them for mixing purposes. Finally, I run through basic gain management examples and explain the need to maintain ample headroom and a strong dynamic range whilst gain structuring.
Plugin used in this video:
Topics covered in this video are:
- Old School Analog Metering
- VU meters including calibrating to the various standards and references
- Learn how to manage the dynamic range of your mixes
- What do the various Parameters refer to
- How to alter Values to suit your mix criteria
- Understanding how meters display values using the various industry standards
- Tips and Tricks