Understanding Signal Flow Basics in Logic Pro X

The release of Logic Pro X marks a significant development for Digital Audio Workstations (DAWs). Not only has the program’s look and feel been redesigned, Logic X features important new functionality and tools that will improve your workflow and the quality of your projects. In this article we’ll take a look at how Logic’s mixer handles signal flow in its audio channels and software instrument channels. Along the way we’ll point out some interesting new features and changes in this version of the program.

Signal flow is the path an audio signal takes from its source to output including all the processing and effects. Understanding this path through a DAW is crucial to any producer or sound engineer. With a solid understanding of each of these stages you can work more confidently and can apply your knowledge to other DAWs, not just Logic X.

Software Instrument Signal Flow

software instrument channel strip

Signal originates with MIDI notes being played back from MIDI regions in the main window. They then  pass  through any of Logic X’s  new MIDI FX loaded on the track. This takes the incoming information  and processes it (ex. arpeggiator, chord trigger, velocity processor) before it triggers the software instrument.

The software instrument’s signal then hits the channel’s Audio FX section. This is where you can load insert  FX, such as EQ, compressor, filters, or any distortion and modulation FXs. Logic now features  gain reduction meters at the top of the channel strip to indicate how much compression is being applied to  the track (note: this only works with Logic’s compressors). You can also easily  access Logic’s EQ plugin  below the gain reduction  meter.

Audio now flows to the main fader which controls the volume. The adjusted signal then passes through the panning stage, which is used to set the signals image in the stereo field. The output is set automatically to the main stereo output of your soundcard. By right clicking on ‘Stereo Out’ you can choose any bus or alternate output provided by your soundcard.

 We aren’t quite finished! Before the signal hits the output of the track Logic makes it easy to split off a copy of the signal by using a bus mix  so that send effects can be used. Send effects are usually time based effects such as  delay and reverb that you don’t want to apply to  the  entire signal. These effects are then routed separately to the  main output.

 Alternatively, you can right click on the bus section. Here you can choose where in the chain you want to  bus  your signal from. The signal  can be taken pre-fader or pre-pan instead of the default setting of post  pan. These  settings are helpful if you are doing alternate sub-mixes.

Audio Channel Signal Flow

Audio Channel Signal Flow

 Logic’s audio channels handle signal flow in a similar way to it’s software instrument channels. The audio originates in the main window  or via an audio input, then passes through the Audio FX section where insert effect processing occurs. The signal then flows through the  fader and the pan where it then is routed out to an output. The bus and send effect routing options are the same as  the software instrument  track.

 It’s important to experiment with signal flow routings in the Logic X mixer in order to understand the full potential of the program. Signal  flow is a fundamental concept in audio production that needs to be fully learned and absorbed. Once this is done your workflow and the  quality of your projects will improve.

Explore royalty-free one-shots, loops, FX, MIDI, and presets from leading artists, producers, and sound designers:

July 14, 2014