Science of Sound: Volume Management (FaderPro)

On one level, understanding the relationship between music and technology, the concept of volume is relatively easy to grasp. From an early age, we learned that there were two buttons on the TV remote: one to make what we're watching louder, and the other to turn everything down.

Perhaps our introduction to changing volume comes on a smartphone or portable speaker with similar buttons, or maybe we learn about volume more organically, like getting frightened by a loud dog bark or covering our ears when passing people working with drills in the street. However that formative experience presents itself, volume seems simple. More is louder; less is quieter.

But when we begin making music and producing tracks, volume can become more sophisticated if we aim to deepen our understanding. For example, we discover that volume can be managed in various ways.

We might experiment with synth plugins with output volume control, but also realize that our chosen workstation has a volume fader in its mixer section. Both of these controls let us change levels. Or perhaps when we're plugging microphones into an audio interface to make recordings, it's only when we turn up the gain that we achieve a strength of signal worth recording.

We soon learn about the relationship between different components of our recording ecosystem, such as the volume of the singer we're recording, the natural volume of the synth, the volume added via plugins, and the volume we balance in a mix with faders and automation. All of these stages and functions control volume level, a relationship referred to as signal flow, which describes a sound moving from origin to destination.

Take the example of recording a vocalist. The signal flow involves the singer performing into a microphone, through an audio interface, and connected to a computer running recording software. Simple volume control might include asking the singer to perform more loudly or quietly, changing the input gain level of the audio interface, or turning the volume fader up or down after the recording is captured.

But we can make the same signal flow much more complex by processing the sound in numerous ways. EQ boosts or cuts the volume of certain frequencies, while compression changes the average level of a performance. Saturation and distortion plugins add volume by increasing harmonics, and reverb delay might make a sound quieter by sharing the signal between a louder dry and a quieter wet one.

Two crucial volume stages are input volume, referred to as gain, and output volume, simply called volume. Gain is vital for controlling the level going into an amp with higher gain resulting in distortion, either subtle or extreme. The volume dial then sets how loud the distorted signal will be, allowing for tonal change without excessive loudness.

This concept applies in analog mixing consoles, where a trim dial at the top of each channel strip controls the input stage. It matters since the level of signals can vary widely, especially between microphone and line level sources. There are also high impedance inputs for bass guitar instruments, ensuring that signal flow matches the source.

Gain or trim dials are critical, whether for amplifier-style tone control or clean recording. It's essential to remember that the volume fader for the channel doesn't adjust the input level but sets the volume once recorded. If input gain is overloaded into distortion, the volume fader can't rectify it. If recorded without enough gain, boosting the output volume will increase noise, affecting the signal-to-noise ratio.

We must understand that volume levels add together from one channel to the next. Overloading a single channel doesn't sound good, and a similar issue can occur at the output stage even if no individual channel is too loud. We refer to the volume gap between the loudest part of a signal and its potential maximum as headroom, leaving enough space not just on individual channels but when summing them down to submixes or the stereo output.

Understanding signal flow and volume through effects is often easier with hardware. If you connect a guitar to a chain of stompbox effects, adjusting volume becomes straightforward, especially with level meters using LED lights. When chaining plugin effects together, some might have a similar ladder of LEDs, while others don't, so it's easy to forget that one effect flows into the next.

Metering can help monitor peak levels and RMS levels, as well as loudness meters measuring LUFS. It's useful to see how volume changes at each stage of signal flow, particularly during mixing or mastering, taking the sum of channels or subgroups and creating a stereo master. This stage might include a chain of effects to control output volume, metering each processing stage.

Understanding volume overlaps with understanding compression, as compression changes the dynamics between the quietest and loudest points of a signal. If we apply compression, we change the volume. We'll touch on how compression and limiting relate to volume in this course, but you may explore the science of sound compression course for more details.

Volume can be as simple or complicated as you make it. Often there's a rush to make things loud, as volume can be impressive. However, throughout the production process, careful thought about volume is vital. Your mixes will benefit if you're patient with signal flow, gain management, and volume automation, saving the hype and volume boost for mix and mastering stages.