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A Brief History of Time Based FX

Or...

Where ‘ere to Chorus, Flange, Phase or just Delay the whole thing.

Time can be a tricky thing, but for our purposes with FX pedals we can define it as the space between the original (“dry”) signal and its processed (“wet”) copy. This space can be expressed in seconds (typically milliseconds, or one one thousandth of a second) and phase. Phase is more important to electrical engineers than it will be here . . . except for Phasers, but we’ll come to that later.

The defining quality of a time based effect is that time is an integral part of how the pedal alters the signal. There are two general categories: Echo (Reverb, Delay and Echo, of course) and Modulation (Phase, Chorus and Flange). Differentiating each effect can be confusing because they all share this one common ingredient. Understanding how time is used will enable you to tell these effects apart and help you add depth to your tone.

Echoes of Reverb

Echo and Reverb are perhaps the hardest to tell apart. They both occur in nature and the two terms are often used interchangeably.

Reverb is a series of random reflections of a sound source from multiple surfaces while Echo is the reflection of a sound source from one or a few surfaces. Those definitions are still pretty vague so let’s look at two simple models found naturally.

Have you ever walked in an empty stairwell? The extra sound your footsteps made is Reverb. The sound bounced off the walls, floor, stairs and ceiling then returned to your ears at various times after the initial step.

The length of time each reflection took is a function of how far the surface it bounced off is from the source (i.e. your footstep). The time base for Reverb is defined by the length of time before the first reflections, know as “Pre-Delay,” returned and how long the reflections last, known as “Decay.”


The classic Echo demonstration is yelling “Hello” from a rooftop or cliff. The “Hello” you hear back after you yelled it is the Echo. The sound bounced off a far building or cavern wall and returned to your ears. If there were more than one repeat the sound bounced off a few surfaces, likely including the one you were standing atop, traveled again to that far wall and reflected back to your ears.


Delay was pioneered by the late, great Les Paul while working with the earliest multitrack tape machine in the late 1940’s. By adding an additional playback head he was able to generate an Echo electronically. This works because the recorded signal passes over the first payback head, producing the recorded sound, then the second playback head a short time later, producing the same recorded sound again.

Generating an Echo this way isn’t just electronic, it’s also mechanical and electromagnetic. The time base of a tape Delay is determined by the distance between the two playback heads and the speed of the tape. Although tape Delays have remained popular, analog electronic and digital circuits have been developed to produce Echo without using tape.

If there is a dividing line between Echo and Delay it’s that the latter typically offers greater control over the various parameters.

And for the record, a duck quack will Echo. Click here for more information.

Next up: Early Reflections.

To check out a great delay pedal click here to view the Jam Pedals Delay Llama series.

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