The Many Uses for Digital Delay

Use your digital delay to produce many more effects than just echo—including flanging, chorus, doubling, and reverb

By Jon Chappell


The two most important effects in a guitarist’s signal chain are distortion and delay. And if you derive your tone strictly from the amp—whether it’s squeaky clean or buzzsaw nasty—then the digital delay is numero uno.

The Deja Vu, by Seymour Duncan, is an example of a delay pedal that includes modulation control, and can therefore be pressed into service providing effects like flanger and chorus, in addition to conventional delay-based effects. (Click images to enlarge.)

Many guitarists think of delay (a.k.a. “DDL,” for “digital delay line”) as the effect that produces an echo sound, and while that’s true, it doesn’t begin to tell the whole story of what a delay is capable of. A full-featured digital delay unit, one with precise controls, complex modulation circuitry, and good display read-outs can produce a range sounds—from flanging to chorus to doubling to ambience to slapback, to discrete repeats that can be synched to tempo-dependent rhythmic values. The Seymour Duncan Deja Vu is one example of a delay unit that includes extensive modulation controls, but other pedals, including the Empress Superdelay and Diamond Memory Lane 2 have them as well.

Many smart guitarists employ more than one delay in their chain, assigning them different duties, even if each has identical parameters. A DDL is one effect that works especially well when chained together with itself. Let’s take a look at the many roles in which a digital delay can serve the guitarist.

BASIC DDL OPERATION

Most people know, or can intuit, the way a delay works: it produces an exact copy (a sample, or digital recording, really) of the original signal in real time, and blends the signals together. The normal parameters are Delay Time (how long in milliseconds after the original sound the copied sound plays), Effect Level (the loudness of the repeated signal relative to the original), and Feedback, which is just another way of saying “number of repeats” (which goes from a single repeat to infinite repeats).

All delays feature two outputs, which allows you to route the original, straight signal to a different place from the effected (repeated) signal. You can get the blended signal from one output (the most common usage) so that you can plug into one input on your amp, as most guitarists do. But you can also send your outputs to two different destinations—to different channels on a stereo amp, to separate mixer channels, or even separate amps entirely to produce a true stereo guitar signal.

With longer delay times, you can create drippy-wet sounds to fill out a slow-note solo in ballad or produce the famous “cascade” sound, which includes Van Halen’s “Cathedral,” Nuno Bettencourt’s “Flight of the Wounded Bumble Bee,” and Albert Lee’s “Country Boy” or his solo on Emmylou Harris’s “Luxury Liner.” With super-long delay times (from a few seconds to several seconds), you can turn your delay into a live multitrack recorder, laying down successive looped passages to jam over. Units such as the DigiTech JamMan, Line 6 DL4, and Boss Loop Station series are loop recorders, and are actually several DDLs in one box that allow for overdubbing loops.

With all these different possibilities at your delay’s disposal, let’s take a look at some sample control settings that will get you on your way to producing the many different types of effects available on a DDL.

TIME DELAY AND OTHER EFFECTS

The length of the delay time is the primary factor in determining the effect you want to create, whether that’s a modulation type (flanger, chorus) or more ambient (reverb, echo). Figure 1 shows a graph of the different effects in order of increasing delay time, shown in milliseconds (thousandths of the second). Most high-end delays have a modulation feature, which is some variation (or variations) on a low-frequency oscillator that sweeps the delay time up and down. Depending on the initial delay setting and the amount of feedback (regeneration), it’s the modulation control that can create a flanger and chorus sound, or generally turning the signal whooshy. Keep the modulation control on zero if you want the delay effect a sound like the original input signal.

Fig. 1. A graph of time in milliseconds and the associated effect produced.

Some stomp box versions dispense with the modulation control, so you won't be able to get a very deep sound in the flanging and chorus departments. But subtle effects that approach a true chorus is sometimes all that’s called for to give a sound a slight sense of movement.

The Feedback control, also referred to as regeneration, determines how many times the output, or effected signal, is fed back into the processor. With the Feedback control at zero, a single repeat is produced, which is good for cascades, harmonies, and loops, but not good for ambient or more swirling textures.

Cranked to the max, the Feedback control produces infinite repeats—or runaway feedback of Feedback, if you will. About five or six repeats are good enough to produce reverb and slapback (an effect popular in rockabilly vocals), as each successive repeat gets quieter, simulating a natural echo.

The Effect Level determines how loud the effected signal is relative to the original input signal. At 0% you won’t hear any effect (the signal comes through dry); at 100% the effect signal is at equal loudness to the original. So if you take the following three steps of 1) setting the delay time long enough (200ms or longer) to hear a separate repeat; 2) putting the effect level at 100%; and 3) applying no feedback or modulation; you will hear two identical repetitions of a note or chord struck once. To a listener who can’t see your hands, it would sound like you played that note or chord twice. This is the key ingredient in the cascade sound, but it’s also good for other rhythmic repeats that are synched to the existing tempo.

EFFECTS SETTINGS

Figure 2 shows how to roughly set your knobs to achieve some different time based delay effects. Exact settings will depend on the musical situation and your particular tastes. But it’s a good idea to establish the time delay first, and then the effects level, before moving on to feedback or modulation.

Fig. 2. A four-knob schematic showing various settings for delay-produced chorus, reverb/slapback, cascade, and loop.

CONCLUSION

Most shorter delay-time effects are “set and forget”; you dial it up according to how it sounds in isolation and don’t have to do anything more for the effect to cooperate with the surrounding music. In other words, one setting can apply to fast or slow tempos, 16th notes, or whole notes. But when the delay time gets past the slapback stage into the 200ms+ range, you have to structure the delay time to the particular tempo and rhythmic values you’re playing. That’s when some math is necessary, but where the real fun begins.

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