Effects Processing - Sends and inserts

Learning Outcomes

  • Explain the difference between insert effects and send effects in a DAW mixer.
  • Choose suitable routing for reverb, delay, distortion, EQ, compression and creative processing.
  • Use buses, auxiliary channels and return channels to create shared and parallel effects.
  • Apply pre-fader and post-fader sends appropriately in a technology-based composition.
  • Describe send and insert choices clearly in a Component 2 logbook.
  • Avoid common routing, gain staging and wet/dry balance errors.

Edexcel A-Level Music Technology (9MT0) Syllabus

In Component 2, Technology-Based Composition, you must show that you can create, edit, structure and process sounds in a musically convincing way. Effects processing is not just a mixing afterthought: it can shape timbre, texture, rhythm, space and drama. Sends and inserts are two core DAW methods for applying effects, and your choices can help demonstrate technical control, creative sound design and a clear response to the brief.

  • Use effects and processors to modify existing sounds.
  • Show control of core effect parameters, not just preset use.
  • Apply creative effects such as delay, pitch-shifting, reverse reverb, distortion or bitcrushing.
  • Use processing to support musical elements such as texture, structure, dynamics and timbre.
  • Record accurate details of effects choices in the logbook.
  • Explain which timbre or instrument was processed and why the processing suited the composition.
  • Use annotated screenshots only when they are labelled and explained.
  • Keep notes as you work so you can report specific settings, automation and routing decisions.

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, look more closely at that area during your revision.

  1. What is the main difference between placing a reverb as an insert and placing it on an auxiliary channel fed by sends?
  2. Why are reverb and delay often used as send effects rather than insert effects?
  3. What is the difference between a pre-fader send and a post-fader send?
  4. Give two examples of effects that are usually suitable as inserts and two that are often suitable as sends.
  5. What details about effects processing should you include in your Component 2 logbook?

Introduction

Sends and inserts are two ways of routing audio through effects in a DAW. Both can be used creatively in Component 2, but they behave differently and therefore suit different tasks. If you understand the difference, you can make better musical decisions, use processing more efficiently, and describe your work more accurately in the logbook.

An insert places an effect directly in the signal path of a track, while a send duplicates some of the signal and routes it elsewhere, usually to an auxiliary or effects return channel. This distinction affects the dry/wet balance, the amount of control you have, CPU use, and how naturally several sounds can share the same space.

Key Term: Insert
An effect placed directly on a track, bus or output channel so that the signal passes through it in series.

Key Term: Send
A routing control that sends a copy of a track’s signal to another channel, usually through a bus, while the original track continues to its normal output.

Insert Effects for Direct Sound Shaping

An insert is the simplest way to process a sound. If you add an EQ, compressor, distortion plug-in or bitcrusher directly onto a synth track, the synth signal passes through that effect before continuing to the output or next channel. This is called serial processing because each processor receives the result of the previous one.

For example, a lead synth might have this insert chain:

  • EQ to remove unnecessary low frequencies
  • Compressor to control level peaks
  • Bitcrusher to create a grainy digital edge
  • Chorus to widen the sound
  • Filter automation to shape the breakdown

This type of routing is useful when the effect is part of the identity of that sound. In a Component 2 composition, a bitcrusher on a lead synth can be a clear example of creative timbral processing. The sound is not merely “mixed”; it has been altered into a new timbre. The Rhinegold guidance for Component 2 gives this type of example: a bitcrusher used to create a grainy synth lead in a breakdown, with the effect described in the creative effects section of the logbook.

Insert effects are also the usual choice for corrective or track-specific processing. EQ is normally inserted because you often want to remove or boost frequencies on one sound only. A kick drum might need low-end shaping, while a vocal sample might need removal of rumble or harshness. Compression is also often inserted because it responds to the dynamics of the individual source.

Key Term: Serial processing
Processing in which the output of one effect feeds the input of the next, so the order of effects changes the result.

The order of insert effects matters. Distortion before reverb gives a distorted dry sound feeding a cleaner space. Reverb before distortion gives a more aggressive, blurred sound because the reverb tail is distorted as well. For creative work, neither is automatically wrong, but you should be able to explain your choice.

Insert effects can also be automated. For instance, you might automate a low-pass filter cutoff to open gradually during a build-up, or automate the mix control of a distortion effect so that a bass synth becomes harsher before a drop. This kind of control is valuable in Component 2 because marks can be gained not just from using effects, but from showing how they are applied, controlled and shaped within the composition.

Test Tip: In your logbook, do not simply write “added effects”. Name the effect, the sound it was applied to, the purpose, and any key parameter changes, such as “automated low-pass filter cutoff from 400 Hz to 8 kHz during the 8-bar build-up”.

Insert effects are not always best. A reverb inserted directly on a track can work for special sound design, but it can also cause problems. If the wet/dry mix is set too high, the original sound may become distant, unclear or washed out. If every track has a different reverb inserted, the mix may sound as though each sound is in a different acoustic space. That can be useful for surreal sound design, but it may weaken clarity if used by accident.

Key Term: Wet/dry mix
The balance between the processed signal, known as wet, and the unprocessed original signal, known as dry.

Send Effects, Buses and Shared Spaces

A send allows part of a track’s signal to be copied and routed to another channel. In most DAWs, the destination is a bus, and the bus feeds an auxiliary channel or return channel containing the effect. The original track still plays normally through its main output, while the send adds a separate processed layer.

Key Term: Bus
A routing path that carries audio from one or more channels to another channel or output.

Key Term: Auxiliary channel
A mixer channel used to receive signals from buses, often hosting shared effects such as reverb or delay.

Reverb is a classic send effect. Imagine a drum kit with separate kick, snare and overhead tracks. Instead of inserting a different room reverb on every drum channel, you can create one auxiliary channel called “Room Reverb”, insert a reverb plug-in on it, and send different amounts from each drum track to that reverb. A kick might be sent at a low level, the snare at a higher level, and overheads moderately. This creates the impression that the kit belongs in one shared room.

This is the same principle as a track sheet that shows several drum tracks sent to a room reverb on a bus, each with its own send level. The reverb bus has the reverb plug-in, while the individual tracks keep their own levels, dynamics processing and panning. This is efficient and musically coherent.

Send effects are useful because they allow:

  • several tracks to share the same effect
  • different send amounts for each source
  • independent control of the effect return level
  • separate EQ, compression or automation on the effect return
  • cleaner dry/wet control
  • lower CPU use than many separate insert reverbs

A delay send works in a similar way. You might create a dotted-eighth delay on an auxiliary channel and send short vocal fragments, percussion hits or synth stabs into it at selected moments. If you automate the send level, only certain words or notes echo, creating rhythmic interest without filling the whole track with delay.

For creative composition, this can be very effective. The source material stays clear, while the delay return becomes a rhythmic texture. You could pan the delay return, automate feedback, filter the repeats, or send the delay return into a reverb for a more distant tail.

Key Term: Return channel
A channel that receives the output of an auxiliary effect, allowing the processed signal to be balanced with the rest of the mix.

When using reverb or delay on an auxiliary channel, the plug-in is usually set to 100% wet. This is because the dry signal is already coming from the original track. If the auxiliary effect also contains dry signal, it can make the source louder, cause phase issues with some processors, or make the mix harder to balance.

Exam Warning: A common mistake is to put a reverb on an auxiliary channel but leave the plug-in at a 50% wet/dry mix. For normal send reverb, set the return effect fully wet and control the amount with the send level and return fader.

Send effects are not only for space-based processing. They can also be used for parallel compression, parallel distortion or special effects. For example, a clean drum loop can be sent to an auxiliary channel with heavy compression and saturation. The crushed return is then blended under the dry drums to add energy while keeping the original transients. This is parallel processing.

Key Term: Parallel processing
Processing in which a dry signal and a separately processed version are blended together.

In Component 2, parallel processing can be a strong creative choice. A found-sound sample could remain natural on its original track while a sent copy is pitch-shifted, filtered and distorted on an auxiliary channel. Blending these signals can create a hybrid timbre that fits a film, game or sound-bite brief.

Pre-Fader and Post-Fader Sends in Composition

Most DAWs allow a send to be either pre-fader or post-fader. This controls whether the send level is affected by the track fader.

Key Term: Post-fader send
A send taken after the channel fader, so lowering the track fader also lowers the amount sent to the effect.

Key Term: Pre-fader send
A send taken before the channel fader, so the send level can remain even when the track fader is turned down.

Post-fader sends are the standard choice for most reverb and delay mixing. If you lower the level of a vocal sample, its reverb also lowers in proportion. This keeps the sense of space natural. For example, if a synth pad fades out, a post-fader send makes its reverb fade with it, unless the reverb tail itself continues naturally after the signal stops.

Pre-fader sends are more specialised but useful for creative work. Since the send happens before the fader, you can turn down the original track while still feeding the effect. This can create “ghost” effects, distant echoes or transitions. For example:

  • A vocal sample is sent pre-fader to a long reverb.
  • The original vocal fader is pulled down.
  • Only the reverb remains, creating a blurred atmospheric texture.
  • The reverb return is automated to swell into the next section.

Pre-fader routing can also be used when creating headphone mixes in recording, but in Component 2 the main creative use is independent control of the effect layer. It lets the processed copy behave like its own instrument.

Another useful technique is send automation. Instead of leaving a reverb or delay send at the same level throughout, you can automate it phrase by phrase. For instance, in a text-based composition, the final word of each line could be sent to a long delay, while the rest of the spoken phrase remains dry. In a game-style brief, a metallic hit could be sent to a huge reverb only when a new scene or level appears.

Key Term: Automation
Recorded or drawn changes to parameters such as level, pan, send amount, filter cutoff or effect feedback over time.

Automation helps demonstrate control. A static preset can sound basic, but an automated send level, feedback control or filter cutoff shows that the effect has been shaped to support the structure and meaning of the composition.

Test Tip: When revising your own coursework, listen with the mixer open and identify every send. Ask: what is being sent, where is it going, is it pre- or post-fader, and what musical purpose does it serve?

Choosing Between Sends and Inserts

The best routing choice depends on what you want the effect to do. If the effect is meant to change the actual character of a single sound, an insert is usually suitable. If the effect is meant to add shared space, rhythmic repeats or a parallel layer, a send is often better.

Use inserts for:

  • EQ on individual sounds
  • compression on a single track
  • gating or expansion
  • distortion, amp simulation or bitcrushing as part of a timbre
  • pitch correction or special pitch effects on one source
  • filter sweeps on a synth, sample or drum loop
  • sound-design chains where the order of effects is central

Use sends for:

  • shared room, hall or plate reverb
  • tempo-synced delay used by several tracks
  • parallel compression on drums or vocals
  • parallel distortion for thickness
  • special long reverb swells
  • dub-style delay throws
  • shared modulation effects where a group needs the same treatment

However, these are not fixed rules. A delay can be an insert if you want a single synth part to be heavily transformed. A reverb can be an insert if you are designing a distant pad or reverse-reverb texture. A compressor can be used on a send for parallel compression. Examiners are interested in whether your choices are purposeful, controlled and musically effective.

For example, consider a composition based on a film stimulus showing an empty city at night. You might use:

  • Insert EQ and compression on a low drone to keep it controlled.
  • Insert bitcrushing on a lead synth in the breakdown for a harsher electronic timbre.
  • A send to a long reverb for metallic found sounds, creating a large empty space.
  • Automated delay sends on short vocal fragments to create rhythmic movement.
  • A pre-fader send to reverb for a transition where the dry source disappears but the space remains.

This gives you several processing types to discuss in the logbook. You can name the timbre, the routing method and the effect parameters. For instance: “Spoken word sample sent post-fader to tempo-synced stereo delay; send level automated on the final word of each phrase; feedback increased from 25% to 55% in the build-up to create overlapping rhythmic repeats.”

Gain staging is also part of good routing. Sends add extra signal to the mix, so reverb and delay returns can increase level and clutter. If the auxiliary return is too loud, the mix may become muddy. If several tracks are sent heavily to the same delay, the return may overload or mask rhythm and melody. Keep an eye on meters, reduce send levels where necessary, and consider filtering the return.

A common professional technique is to EQ the effect return. For example, insert an EQ after the reverb plug-in on the auxiliary channel and remove low frequencies. This can stop reverb from muddying the bass range. A delay return can be filtered so repeats sound thinner and sit behind the dry source. These are good decisions to mention because they show technical control beyond simply adding an effect.

Exam Warning: Do not assume that more effects mean higher marks. Overuse of reverb, delay, distortion or modulation can obscure melody, rhythm and structure. Effects should support the brief and the musical idea.

For Component 2, the logbook matters. You should keep notes from the start of your project, because effect settings often change as the composition develops. If you wait until the end, you may forget which sound used which plug-in, which sends were automated, or what parameters were changed. The guidance for the composition logbook stresses that screenshots should be annotated and placed in the relevant table cells; unlabelled screenshots do not explain your work.

A strong logbook entry might include:

  • the instrument or sample name
  • whether the effect was an insert or send
  • the effect type and plug-in name if useful
  • main settings such as decay time, feedback, mix, filter cutoff or bit depth
  • automation details
  • the musical or dramatic reason for the processing

For example: “Glass hit sample: sent to Bus 3 ‘Long Reverse Reverb’. Reverb audio reversed and faded in before each impact to create a sucking transition into scene changes. Return EQ removes low frequencies below 250 Hz to avoid masking the bass drone.”

This is much more exam-ready than “added reverb to glass sound”. It tells the examiner what you did, how you controlled it, and why it mattered.

Key Point Checklist

This article has covered the following key knowledge points:

  • Inserts place effects directly in a track’s signal path.
  • Sends route a copy of a signal to another channel, usually through a bus.
  • Reverb and delay are often used on auxiliary channels so several tracks can share one effect.
  • Insert effects are well suited to track-specific EQ, compression, distortion, filtering and sound design.
  • A send reverb or delay return is usually set to 100% wet.
  • Post-fader sends follow the track fader and are common for natural reverb and delay balance.
  • Pre-fader sends can create independent effects such as ghost reverbs and transition swells.
  • Parallel processing blends a dry sound with a separately processed version.
  • Automation of send levels and effect parameters can show creative control.
  • Effect returns can be EQ’d or compressed to help them sit in the mix.
  • Component 2 logbook entries should name the sound, effect, routing, settings and purpose.
  • Effects should support timbre, texture, structure and the chosen brief rather than covering weak musical ideas.

Key Terms and Concepts

  • Insert
  • Send
  • Serial processing
  • Wet/dry mix
  • Bus
  • Auxiliary channel
  • Return channel
  • Parallel processing
  • Post-fader send
  • Pre-fader send
  • Automation