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Effects Explained: Echo, Delay, and Reverb

Dave Hunter
|
07.10.2008

Adapted from the book Guitar Effects Pedals: The Practical Handbook (Backbeat Books)

We all know the sound of this effect: It replicates varying degrees of the sound of playing your guitar in the gym showers, a cathedral, or Mammoth Cave, and it has proved itself one of the most atmospheric aural adulterations available. Since none of those locations is entirely gig friendly, however, our ever-handy techs have bottled the flavor in a reliable, portable form. This category covers both echo and reverb effects, since they are versions of the same thing. The term “echo” was used more often in the early days, and is sometimes used today to refer to the distinct and distant repeats of a signal, while “delay” refers to anything from the same, to the short repeats heard as reverb, to the complex, long, manipulated repeats of an intricate digital delay line. Either way, they are both really the same thing, just used differently.

Analog Delay   

The transmogrification of bulky, fiddly tape echo units into transistorized analog echo pedals in the late 1970s is arguably one of the greatest economies the delay-loving guitarists has ever experienced (physically more than financially). Players addicted to anything from slapback to the hypnotic sonic cloning of their Echoplexes, Copicats, and Space Echoes breathed collective sighs of relief when Electro-Harmonix and MXR introduced relatively affordable analog delay pedals. By the early 1980s there was barely a rocker going who stepped on stage without a delay pedal, and every major effects maker offered a model or two. Many players gradually decided that their old tape echoes actually sounded better than the transistorized alternatives, but for Fulltone Tape Echoconvenience sake a majority of these still stuck with their stompboxes for live work. Opinions on the tonal superiority of tape echo—and especially tube-powered versions—have become even more vehement in recent years, spawning high prices in the used market and even the recent offering of a Tube Tape Echo from boutique pedal maker Fulltone, but many still find tape impractical.

Like so much else, analog delays were first made possible by a shift in the available technology in the mid 1970s, in this case the advent of affordable delay chips. Techies call these “bucket brigade delay chips” because they pass the signal along in stages from the input pin to the output pin—with as many as from 68 to 4096 stages. Inject a signal, govern the speed at which it gets passed from stage to stage, tap the output and, voila, you’ve got echo. It’s clear from this that the more stages in the chip, the longer the delay the circuit can achieve. The longer the delay, however, the greater the distortion in the wet signal, so most makers compromised to keep maximum settings within acceptable delay/noise ratios.

Electro Harmonix Deluxe Memory ManElectro-Harmonix’s Memory Man was one of the most popular solid-state delays ever, and even with its meager 5 to 320 milliseconds delay time was little short of revolutionary upon its introduction in 1976. At around $150, it was something of a bargain, too, though not dirt-cheap by any means—considering that at that time you could buy a new Stratocaster for just a little over three times that figure. The Memory Man was launched with Reticon SAD1024 chips, but E-H switched to quieter, better sounding and more adaptable Panasonic MN3005 ICs when these became available, and the latter is the chip found in the better-known Stereo Echo/Chorus and Deluxe models.
Different forms of manipulation of similar bucket brigade delay chips were also at the center of the more advanced chorus and flanger pedals that emerged in the late 1970s. With ICs that themselves were capable of creating a controllable time delay in any given signal, the job of harmonically modulating part of a split, delayed signal to produce a warbling chorus or swooshing flange sound became a lot easier.

Digital Delay

The wonders of digital delay arrived on the pedalboard in the early 1980s with what seemed massive capabilities of long delays, clean signal reproductions, and the endless fun of one, two, or up to 16 seconds of looping delay. In many cases, in the early days, reproductions weren’t really all that clean (or were cleaner than analog, but colder and harsher too), and many delays were prone to digital distortion if pushed, or poor resolution on the decay of the signal. Even so, the techno-power of the new technology stamped all over the bones of the old analog delay units, and for a time threatened to bury them entirely.

Boss DD-7As for the nuts and bolts of digital delays, any thorough, from-the-ground-up explanation is more than can be entered into in this space (and most of you at least know the basic principle behind binary encoding by now anyway, right?). Simply think of the digital delay pedal as another form of sampler: it makes a small digital recording of your riff, and plays it back at a user-selectable time delay, with depth and number of repeats also more or less selectable. The higher the sample rate, the better the sound quality. Early affordable 8-bit models really did leave a lot to be desired sonically, but as 16, 20 and 24-bit designs emerged, the reproduction of the echoes increased dramatically in quality.

As with so very many elements in the great world of guitar, however, once the novelty wore off and we were less awestruck by the new technology—and, in many cases, came to realize that we had little use for 2 seconds, or even 500 milliseconds of delay time—many of us came to miss the warm, pliable sound of the analog pedals. Today, as with all such things, the jury is still out; plenty of great players use each type of pedal, and the music you make with the technology remains more important than the type of technology you choose to use to make music. Used in isolation, at the same delay settings, each would probably sound just a little different to a guitarist with good ears. At the back end of a pedalboard with eight or ten other effects on it and three or four running at a time, the differences are likely to be negligible—but different players have different preferences, depending on what makes them feel good about their tone.

Reverb

Achieved with springs or plates, as in the early days, reverb is a distinct sound all its own. The effect has been lured in to the delay camp more in modern times because the same bucket brigade analog technology or digital delay technology that is used to create long echoes can be manipulated to produce a reverb sound, too. Tap the multistage analog delay chip at a very short delay, and layer these with other such short delays, and a reverb effect is produced. It has something in common with the spring reverb in guitar amps—or old studio plate reverb units—in that both approximate the reverberant sound of a guitar played in an empty, reflective room. While many players make good use of reverb pedals, including anything from Danelectro’s newer, far-eastern-built units to old and new Electro-Harmonix and Boss models, most consider the amp-based, tube-driven spring reverb to be the pinnacle of the breed. But there are many great guitar amps out there with no reverb onboard, so for anything from your tweed Fender Bassman to your Marshall JTM45 to your Matchless DC30, an add-on unit is the only option.

Fender Tube ReverbYou couldn’t call it a pedal, but Fender’s tube reverb, in its original or reissued form, has always been considered one of the best spring reverb units around, and can be added at the front end of any amp (although this isn’t ideal if your overdrive sound comes from a channel-switching overdrive preamp placed after the reverb). Other amp makers in the USA and the UK also offered stand-alone reverbs, plenty of which can sound totally fabulous. Fender was actually a little slow getting onboard reverb into its amplifiers, though, and makers such as Gibson and Ampeg offered combos with fantastic sounding built-in reverb in the early ’60s.

A spring reverb unit is really a small amplifier in itself, that sends the guitar signal through a tube circuit to a small output transformer (or through a transistorized circuit) and from there to one end of the springs in a spring can rather than to a speaker. This signal vibrates the springs, is picked up by a transducer at their opposite end, and from there is blended back with the dry signal by degrees determined by a “depth” control, and sent on to the output (or the power tubes, if part of a guitar amp). As you can image, it’s a bulky effect when achieved in this way, requiring at least a couple of transformers, two or three tube sockets and a spring can, but the circuit itself is fairly simple.

Boss Digital ReverbDigital reverbs, like their sibling delays, offer more power and a greater variety of settings. And in addition to doing some approximations of spring reverb sounds, digital units usually offer more “lifelike” reverberation as heard in anything from an empty room to a large concert hall, if you want to add a synthesized “natural” room sound to your signal rather than merely replicate the classic sproing of springs. A few pedals do this very well, but most such devices are rack units that are best used in an amp’s FX loop, and are beyond the scope of this article. For all the power of digital reverbs, however, there are plenty of guitarists who just don’t warm to them, and the tube-driven, analog, spring reverb effect remains hands-down the favorite for guitar.

Next installment: filtering and EQ.

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