Delays
A delay produces discrete repeating echoes of the source material at a specific interval. In digital delays, the input signal is sampled or recorded into the memory, where it is held for the amount of time you specify with the delay time setting, after which the sample is played back at the output. Since the conception of the delay unit, both analog and digital effects have stayed with most units just as strongly as one another. As analog delays often created a slightly distorted, modulated sounding delay, the sound is dramatically different to a digital delay which is a much cleaner and stronger signal. Depending on the desired sound and application there is no one reason why you would choose one over the other. Another type of delay which generally fits into analog delay is tape delay. Magnetic tape was used to create the first form of delay which can be replicated using digital technology. The high end usually deteriorates with every repeat but produces a very warm sound. The advantage of digital technology of course is that no tape needs to ever be replaced!
There are many different types of delay:
Standard Delay - Simply straight delay with the amount controlled by the user
Eight Note Triplet - For every quarter note going in, 8th note triplets come out.
Slap Delay- This usually uses a very short delay time (up to 250ms) and has little or no feedback. Creates a vintage, Blues, Rock and Roll sound.
Swell - This adds a volume swell to the defined delay time. Create a very pleasant, warm sounding effect.
Ducking - The volume of the echoes are "ducked" (reduced) while a sound is going in and increase when it isn't. Useful in adding clarity to a tone.
Multi - Adds multiple delays to give a rhythmic variation.
Ping Pong - Simply put, this adds a distinct stereo effect to a dry signal by alternately positioning the delay in the left and right field.
Reverse - As the name suggests, the input signal is reversed. This is controlled by the delay time and the mix to adjust whether all the sound is reversed or some of it.
Parameters
Delay Time - This sets the maximum delay time available to each delay voice (in stereo units).
Feedback/ Repeat - This controls the fade time of the delay repeats. Higher settings take longer to fade out. Usually this dial goes up to infinity so the delay would keep going forever.
Tap - Often delay processors have a tap function which allows the delay time to be changed on-the-fly.
Modulation - In units which produce both analog and digital delay, the modulation knob adjusts the amount of the "warble" sound.
Pan - Unless controlled by the type of effect, the positioning of the delay can be sent to either field.
Mix - Controls how much of the delay is mixed with the dry signal.