Let’s switch directions at this point. We are going to leave acoustic theory and head back to technical knowledge of audio production.

When working with audio there are many moments and reasons for needing to process this audio in some way. You have already gained some experience with this. When applying amplitude “gain” (amplifying or attenuating) either via the section gain, track trim, or volume automation, the audio signal is being processed.

When we discuss changes to an audio signal’s volume or amplitude, we will use the following terms;

• amplify: this means multiply, boost, or make louder.
• attenuate: this means to reduce a signals strength.

Altering a signal is known as Signal Processing. Signal processing is the act of affecting, changing, or altering a signal to meet some desired output. Altering the amplitude or gain of an audio signal is one basic form of signal processing.

When working with sound, there are many reasons for altering or processing that sound. Likewise, there are many (_many, many, m a n y . . . _) ways of processing sound.

Analog FX and Inserts

A DAW is set up to handle the amplitude based processing of audio sounds in the ways you have explored over the last few weeks. It is baked into the DNA of a DAW, if you will, through the mixer and track-based fader setup we are used to seeing by now. As we have learned, DAWs adopted this setup as a way of mimicking the tape-based studio’s of the 20th century. In these tape-based studios, affecting the relative amplitude relationships between tracks was central to the work-flow, much like it still is today.

Another work-flow developed in tape-based studios, which has been ported to the digital audio workstation, is that of “effects inserts.” In addition to amplitude adjustments, audio/sound engineers have developed many ways of changing and processing sound. Some of these include:

• equalization
• compression
• limiting
• exciters
• chorus
• distortion
• reverb
• delay

In analog studios, these effects were separate hardware modules, with audio inputs and outputs. To use one of these, the mix engineer or artist would have to “patch” the effects (or simply FX) unit into the desired signal path. There are places within the signal flow path where this patching can occur, and these locations are typically known as inserts.

An insert allows the engineer to take an audio signal out from the signal path, run it through the FX unit, then insert the resulting sound back into the original signal path.

In an analog studio, this is typically done in one of three ways.

1. Utilize an “insert” point on a mixing console.
   • Mixing consoles typically have “insert” points, in the form of 1/4” connectors. These “inserts” will do exactly what’s described above, where they take the signal away from a track or channel, then bring the affected signal back in.
2. Use an FX send or “Bus”
   • A Bus splits the audio signal off from the track.
   • Unlike an insert, a bus does not replace the signal flow with the affected sound. Instead, this can be thought of as a new copy of the signal. (You will learn more about busses in the coming weeks)
3. A Patch Bay
   • Although a “Patch Bay” is actually some combination of a bus and/or an insert and therefore is not a unique method for adding audio FX, their flexibility is something to be aware of.
   • A Patch Bay (as seen in the below image), allows the engineer or artists to flexibly connect any output in their analog studio to any other input in their studio. (This assumes that the designer of the studio has thought through all of the possibilities before building the patch bay)

Plug-Ins

There is of course a huge need for sound processing FX and software in the digital-based audio studio as well. As you can imagine, since software development democratizes accessibility in many ways, there are so many amazing signal processing options out there, with new ones being introduced all of the time.

In the digital-based studio, the colloquial term that is predominantly in use for these software applications is plug-ins.

A plug-in is a dedicated piece of software, that processes audio signals, and is hosted within a DAW. These software programs do not typically function outside of the DAW. Instead, they require the architecture of the DAW to get audio in and out of them.

Depending on the DAW, the place that you add plug-ins may be called “inserts,” “plug-ins,” or “FX.” So please encode in your head that these three terms are basically synonymous.

Reaper uses the “FX” terminology for the location that you add “plug-ins.” The following image shows how you access plug-ins or FX in Reaper. The two red circles highlight the “FX” button that can be used to open the FX window. The orange box is the FX chain, where you can see the signal flow between FX.

Usually, FX plug-ins are located “pre-fader.” This means that the audio signal is output to the FX, and re-input from the FX to the track before the amplitude fader and pan pot.

To add an FX plug-in in Reaper, you can either press one of the FX buttons (either from the TCP or the mixer), or click directly on the FX chain. (note: if you cannot see the FX chain in your mixer, click and pull-up on the mixer window within Reaper.)