Audio Signal Flow

Signal flow is the universal language behind the path of audio in any recording and production scenario.

Understanding and applying signal flow is one of your best tools to increase productivity and avoid stumbling blocks. The more you know the more creative you can be.

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Understanding and applying signal flow is one of your best tools to increase productivity and avoid stumbling blocks.

The physical aspects of signal flow determine the flow of sound and its connections all the way from its source, capture, processing and output. In a recording situation, this would be the sound source — for example spoken voice into a microphone. The sound is converted into an electrical signal by the microphone and travels down most typically a XLR microphone cable and into the preamplifier and brought up to line level.

The electrical side of signal flow really comes into focus once we hit the preamps and what today will most likely involve an analogue to digital conversion that pipes the signal into your digital audio workstation and through the various stages like EQ, DSP, panning, busses, and faders. The last stage in your digital audio workstation, or DAW, are the main outputs that feed the digital to analogue conversion and final delivery.

Analogue layouts are still the best way to demonstrate because of their highly visual and physical layouts that allow you to relate sight and feel to the different routings. These concepts easily transfer over to digital environments and also apply on a smaller scale, like a small four input/output audio interface.

Signal Flow Chart

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Audio routing is built on a set of stages that follow a sound all the way from its source, input and conversion, channel strip, output stage and ultimately through the speaker and into your ears.

Signal Flow – How it works

I hope you had a good look at the previous diagram. Regardless of whether it’s a digital or analogue environment, the same flow will exist. Audio routing is built on a set of stages that follow a sound all the way from its source, input and conversion, channel strip, output stage and ultimately through the speaker and into your ears.

With a modern DAW, the mixing console is replaced by a computer, channel strips go digital, and the input stage becomes an audio interface or dedicated microphone preamps and A/D and D/A converters.

Input Stage

This will include everything from the sound source and microphone to the mic preamp. Input gain, line level, padding and input type (mic or instrument) are set here and then feed the Analogue to Digital converter.

The Channel Strip
Channels flow from top to bottom, making their way down through the input selector, filter/EQ section, inserts & plugins, bus & output selector, panning and the track fader.

Sends
Busses send and receive audio to and from various places and can be used both individually or in groups. DAWs tend to treat busses and auxiliary channels as being the same. Busses are an ideal way of managing external effects like reverb and delay.

Outputs
All roads lead to your master stereo output, along the way you would have encountered aux, bus group outputs and monitor outputs. The last output stage is used to drive signal to your speakers or speaker amplifier. Every audio signal assigned to the main output is summed into a stereo signal.

The other output types are used to send signal out to other equipment, to organize like sounds into easier to control groups and to create monitor mixes.

Video Production

Audio Capture

Recording in studios can be a fantastically complex and exotic means of capturing sound. The quality of the space, its microphone selection, and mixing environment are what allow room for creativity and precision. Consider the following and how it applies to your current environment, regardless of size and scale.

• A clean sounding room
• Good microphones and preamps
• A healthy collection of outboard gear and plugins
• Flexible signal flow

Sound Mixing

Mixing can be demanding, but it also rewards those with an ear for detail and creative routing designs. Half of the fun is getting all the equipment to talk to each other. You can then start to use different pairings of mics and preamps, EQ and compression during recording, and generally turn your mix on its head.

HALF OF THE FUN IS GETTING ALL THE EQUIPMENT TO TALK TO EACH OTHER.

Analogue studios or large format boards are ideal places to learn because of their scale and hands on nature. To that end, routing is a lot more fun and really makes you think about all the potential. However, learning to make do with finite numbers of channels, busses, auxiliaries and effects teaches you to stack and combine elements in natural sounding ways. For example:

• Sending multiple effects tracks to a single bus handling reverb. This blends the sound together and places them in the same location.
• Using side chains to use one track to drive another track
• Bypassing the boards channel strip and patching your own compressors and EQs during recording

Live Video

The job by nature requires a degree of problem solving, preferably in the planning stages. Adapting to new requirements, setups and equipment is part of the job. A big part of this is reading ahead and familizaring yourself with any gear you will be using on your next gig. Signal flow is the key to understanding new equipment, planning and thinking on the spot when things don’t quite go to plan.

Living with Signal Flow

Just like any other heady concepts, signal flow dawns on you in stages, from the initial intake of information, through application and letting it settle in as your brain connects the dots.

From here on you will be more and more conscious of the input and output stages your equipment uses. You start to realize that the auxiliary microphone in your camera is too tinny and decide to invest in a dedicated microphone and recorder. Your computer’s built-in soundcard starts to fall short on latency and conversion, so you invest in an audio interface and higher impedance headphones.

Music and film audio can become a challenge because you become more and more aware of a setup’s shortcomings. From source signal, to cables, to amplifiers and speakers; they all add up and make a difference.

The common theme is that you are constantly looking at your workflow and identifying each component and how it impacts your project. The result is less guesswork and time wasted spent figuring out how components work. This makes all the difference, taking you from being only a passenger to calling the shots instead.