1. Signal Output Send effect Send/Return effects Definition:
An effect added to the direct signal on a track or mixer channel via an auxiliary send/ return prior to the output
The amount of effect can be controlled by adjusting the auxiliary send and / or return levels on the mixer
Signal
Output
Send effect

2. Send/Return effects Send/Return effects in ProTools:
Several steps must be followed:
Create one or more Aux Input Tracks (File > New Tracks > Mono Aux Input or Stereo Aux Input)
Assign the effect(s) you want to the Aux Input track’s insert(s)
In the Aux Input edit window track or mixer channel’s I/O settings, assign the Aux Input track’s input to a bus, and raise the level fader of the aux input track to unity gain
Activate View > Edit Window Shows > Sends View or View > Mix Window Shows > Sends View to see the Sends pull down menus.
Activate the send on the track by selecting its bus in the sends pull-down menu (active buses will then appear in bold).
A level fader for the effect send will appear; raise it to the desired level and the effect will be applied to the track.

3. Send/Return effects Reverb
Definition: a device or plug-in that simulates acoustic reverberation, a series of complex sound reflections varying with the size, proportions, and reflective surfaces of an interior space.
Digital reverbs simulate acoustic spaces by providing programmable parmeters such as room size, room type, decay, etc.
Usual use is as a send/return effect, but can also be used as an in-line effect if RAM memory permits. Playing with the mix between direct signal and reverb then becomes a consideration.

4. Send/Return effects Reverb ProTools D-verb: Reverb controls:
Input: the level of the incoming signal. Prevents clipping or boosts weak signals.
Mix: leave at 100% if used as a send / return effect. Adjust the dry / wet balance if used as an insert
Algorithm & Size: presets for the 5 parameters below.
Diffusion:sets the density of the initial echo buildup of the reverb. High settings make for intense reverb very soon after the signal passes through the reverb (good for bright percussion, e.g.) Low settings make for a more natural buildup of reverb suitable for vocals, strings and other sources.
Decay:the reverb time. How long it takes the reverb to die out once the signal stops.
Pre-delay:the amount of time that elapses before the reverb sets in.
HF cut: the lower the setting, the faster that high frequencies in the reverb decay.
LP filter: an overall low-pass filter cutting high frequencies in the reverb at a rate of -6 dB per octave.

5. Send/Return effects Delay
Definition: a device or plug-in that delays the input signal by a set number of milliseconds.
In addition to the delay itself, a feedback control feeds the delayed signal back into itself to varying degrees (expressed as percentages) and generates diminishing or infinite repeats of the delay
Most digital delays also include a filter to make the repeated or single delays sound ‘duller’, similar to a real acoustic echo.
ProTools’ delay also includes modulation, a cyclic pitch variation of the delayed signal used to create chorus and flange effects.
The delay repetitions can also be synced to a tempo for musical purposes.

6. Send/Return effects Delay Uses:.
A short delay (less than 40 ms) acts a bit like an EQ, in that it reinforces or cancels certain frequencies due to phase differences it causes.
Slap echo is obtained with slightly longer delay times (40 to 170 ms), and adds a type of ‘ambience’ to the effected sound.
Medium ( ) and longer delays (680 ms +) are generally used for musical and special effects. The repetitions of the sound are distinctly audible, and tempo sync considerations come into play.