Reverb became one of the fundamental pillars for the music of the ‘60s: in particular, the Plate Reverbs and Echo Chambers. Learn what makes Abbey Road’s Plate and Chamber Reverb so unique, and how to use them effectively in your music with Waves Audio.

In 1947, artificial reverb as we know it today was born in a bathroom — Bill Putnam’s bathroom, to be exact. It provided an echo chamber effect for the Harmonicats’ recording of Peg O’ My Heart. Echo chambers remained the dominant type of artificial reverb until 1957 when EMT introduced the first plate reverb.

Echo chambers became more refined over the years but were always relatively small, purpose-built rooms with highly reflective and usually non-parallel surfaces. A speaker in the room played back sound, typically from a mixer’s reverb bus, which was picked up by a mic, or pair of mics for stereo. Many of the reverb effects on legendary recordings came from chamber reverb, and studios were often fiercely proud of their chambers’ unique aspects.

Abbey Road Chambers were no exception. One of their techniques was using equalisation to alter the frequency response of the audio being reverberated. In particular, reducing the low-frequency response counteracted the longer decay of low frequencies compared to higher ones and kept reverb from contributing lower midrange muddiness. The Abbey Road innovation that stretched the creative boundaries of that time was the S.T.E.E.D. (Send Tape Echo Echo Delay) process, which incorporated tape delay (with EQ in its feedback path) as well as post-delay EQ. Integrating delay with feedback could increase the reverb decay time and add novel echo effects along with the reverb.

Compared to concert hall-based acoustic reverb, a chamber’s small size had very little pre-delay and imparted a different, denser quality. Halls tend toward a more diaphanous, airy sound, while chambers are more about character and colour. But like all acoustic forms of reverb, chamber reverb starts with early reflections made by a volley of individual echoes. As they bounce around the room, the number of echoes increases while their level decreases, thus creating a complex and diffuse reverb tail. The high-frequency response also tapers off over time (this is called damping).

Plate reverbs are a form of electro-mechanical reverb based on a large, metal sheet (the EMT 140 plates Abbey Road used were about 4 by 8 feet.)

The upper part of the Abbey Road Reverb Plates graphic represents the metal plate which was suspended vertically. Note the plate selector switch, which could choose among four different plates.

A driver pumps sound into the sheet’s center, and pickups attached to the metal pick up the sound. Plate reverbs are fundamentally different from reverb where the sound waves go through the air because sound travels faster in metal, and higher frequencies travel faster than lower frequencies. There’s no significant pre-delay unless you add it artificially. With the Abbey Road Plates plugin, pre-delay is variable from 0 to 500 ms. Because the plate is flat, the echoes multiply rapidly as soon as the driver transfers vibrations to the plate. This immediately gives a highly diffused, smooth sound—diffusion doesn’t take time to build up, as it does with acoustic spaces.

Damping is also more pronounced than with acoustical reverb, which follows a relatively constant loss of high frequencies as the reverb decays. Instead, plate reverbs start bright but the brightness decays relatively quickly compared to the midrange and lower frequencies, which bloom later in the decay. Another difference is that plate reverbs can exhibit more resonances during the decay compared to a chamber or hall.

As an analogy, consider film vs. CGI. A chamber is more like film—it captures real life. A plate is more like CGI graphics, which create a “perfect”-looking object. Plates are smoother, with diffusion that’s more consistent throughout the decay. The resonances also contribute a certain metallic quality that, while pleasing, creates a dusting of artificiality. Chambers rather, cue your ears that you’re listening to the real thing.

When deciding whether to use chamber or plate reverb, the simplest option is to insert both, dial up an appropriate sound on each one, then toggle back and forth to decide which one you like best for the track. It’s important to take context into account. We associate sounds with certain spaces: you hear drums in a room, not in a metal plate. Yet, that metal plate can add a distinctive vibe to vocals, especially if the rest of the band is bussing into a room reverb. Several instrument types are equally at home with either type of reverb, depending on the context.

Although reverb is about adding space to music, it’s also making a statement—and generally, a piece of music’s individual parts will flow better when they speak with a unified voice. The overall sound just won’t seem right if half the band is going through plates and the other half through chambers of different sizes. However, there are situations where adding a different reverb can bring attention to a particular sound and provide a welcome contrast. While it’s good to be an audio architect and have a strategy about the kind of space you want to create for the music, also be open to breaking the rules. After all, that’s how some of the most iconic records of all time were made.

The bright and fast onset, and relatively quick decay into a bassier sound makes the Abbey Road Plates a good choice for acoustic guitar, hand percussion, piano and percussive synthesizer sounds—anything where you want to accentuate the note attack. The brightness also gets out of the way fairly quickly, so it doesn’t compete with the body of the sound.

Vocals are a prime candidate for plates. The diffuse, smooth, slightly artificial character puts a sweet sheen on vocals. Its slightly artificial character is also a good match for electronically oriented material. To my ears, synthetic music somehow fits better with non-acoustic reverb.

The relatively neutral aspect of plate reverb also makes it a good companion to room reverb. If there’s a good room sound, the plate provides a kind of sonic caulking to fill in the gaps in the room sound. It’s also good on a snare to bring attention to it and lift it out of the overall mix a bit by providing a more distinctive ambiance. Finally, the occasional reverb splash on the snare, and plate reverb is great because it hits hard initially to the make the point, then trails off.

The bottom line is when you want smooth, polite, evocative reverb that enhances the source but doesn’t get in its way, a plate reverb is ideal.

The ideal choices here are almost the opposite of a plate because a chamber’s hallmarks are color and character. Rock, R&B and hip-hop vocalists work well with chamber reverb. While I prefer plate on solo acoustic guitar, chamber on guitar amps is a joy, and often the best choice for acoustic guitar when it’s part of an ensemble that’s also going through acoustic-based reverb.

Also, consider that some instruments can go both ways. For ambient piano, a plate reverb will likely match the music better. For a more classical feel—where the piano sound is inextricably wedded to the sound of an acoustic space—the chamber is more appropriate. Ditto rock piano, Hammond organs and brass.

Drums are good candidates for chamber reverb. Today’s drum recordings tend to sound drier than they were a couple of decades ago when drums were often drowned in gauzy reverb. I’ve always felt acoustic drums sound more appropriate in a “real” room because that’s how we’ve heard them all our lives.

Chamber also works well as a bus reverb. In pre-digital days when multiple instances of reverb were rare, reverb was limited to being a single effect in a bus. You’d use channel send controls to decide how much of each musician went into the reverb chamber; more reverb placed the musician further back in the mix. Chamber reverb still rules for this kind of application, especially for more vintage-sounding recordings.