“How sweet the answer Echo makes

To music at night,

When, roused by lute or horn, she wakes,

And far away, o’er lawns and lakes,

Goes answering light.”

– Thomas Moore, from Echo (1821)

From rockabilly slapback to long, spacy repeats on a searing lead, we guitarists love delay. It’s one of our most beloved effects—which makes it a subject well worth repeating. (Sorry, couldn’t resist!) Echo and reverb are the oldest of all effects, and our desire to hear them is evidenced throughout history in monasteries, cathedrals, and concert halls specifically designed to create them. The advent of electronics brought new possibilities for the creation of these effects, taking the evolution of echo into the modern age.

In terms of signal processing, delay is essentially a form of echo. A naturally occurring echo is the repetition of a sound due to reflection off of a physical surface. But this also describes reverberation. In fact, there’s quite a bit of overlap in what is commonly considered reverb, echo, and delay. So, what’s the difference? In the case of reverberation and echo, the difference is time—the length of time between the original and the repeated sounds.

Delay, however, is a unique and essentially man-made phenomenon. This is because, as applied to signal processing, delay is a single repetition of a sound, isolated and without any accompanying reflections. This is an artificial occurrence and doesn’t happen in nature. Whether a sound is made indoors or outdoors, it is never reflected back strictly from a single source. Sounds are reflected from multiple surfaces, and the reflected sounds are likewise reflected, causing multiple reflections at various intervals and volumes. Even the distinct repeat you hear shouting “Hello!” in a cave or across a massive canyon is not without ambient reflections of some sort. Although the delay is long between the source and reflected sounds, because of the multiple reflections, these events are more appropriately deemed echoes.

For the true echo connoisseur, nothing is more highly prized than the Italian-made units of the late ’50s and early ’60s.

The irony is that, though we’re only able to achieve true delay through electronic signal processing, in a more abstract sense the original meaning of “echo” more closely resembles what we’ve just been describing as delay: In Greek mythology, the nymph Echo distracted the goddess Hera with conversation to prevent her from discovering the numerous affairs of her husband, Zeus. When Hera discovered Echo’s trickery, she cursed the nymph by taking away her power of speech—except for the ability to repeat exactly what another had just spoken.

Obviously, “echo” has since taken on much broader meaning as both a noun and a verb describing any sort of reflection or repetition of sound. Therefore echo will be included in the early part of our look at the history of delay as an outboard effect. Now, let’s look at some of the ways echo and delay effects have been created.

Echo ex Machina
The history of electronic effects runs parallel to the history of recorded music. The creation of an ambient setting could be thought of as the first effect to be used in recording. Studio engineers realized the physical characteristics of the room being performed in affected the outcome of the recording. A room with reflective surfaces, such as tile or concrete, created natural reverb. A larger room yielded an echo effect. These “live rooms” were some of the earliest and most widely used studio effects. “Echo chambers” purposely built for use in broadcast and recording date back to 1931.

An echo chamber is a very large room, usually with a playback system at one end of the room and a microphone at the other. Recording pioneer Bill Putnam Sr. is credited with being the first to employ a send-and-return method on an audio console in order to vary the amount of echo in a recording. Phil Spector’s famous “wall of sound” recordings from the 1960s are a great example of the echo-chamber effect. Echo chambers were commonly employed in commercial recording up until the 1970s, when multi-tracking, close-miking, and more sophisticated studio effects changed the way commercial recordings were made.

Many of the recording techniques still commonly used in studios today were pioneered by Les Paul back in the late 1940s. One of Paul’s more notable tricks was to add an extra playback head to his tape recorder in order to achieve a slapback echo effect. This innovation marks the point where true delay was first used as an effect, independent from echo and reverb.

As this slapback effect was employed on more and more recordings, it created demand for a way to reproduce the effect live. Ray Butts of Cairo, Illinois, was the first to step up and meet this demand when he was asked to build a device that would recreate the type of echo that Les Paul got on his records. Ray’s solution was the EchoSonic amplifier with built-in tape delay.