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Plate vs. Chamber Reverb: Abbey Road Plugins Compared

Jul 09, 2019

Reverb molded the sound of vintage recordings. Learn what makes Abbey Road’s Plate and Chamber reverbs—used by the Beatles and Pink Floyd among others—so special, and how to use them effectively in your music.

Plate vs. Chamber Reverb: Abbey Road Plugins Compared

By Craig Anderton

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.

The Echo Chamber

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 equalization 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 their 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 color. 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).

A Full Plate of Reverb

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.)

Abbey Road Reverb Plates

Abbey Road Reverb Plates

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.”

Analog Reverb Treatment

Those raised in the digital age often assume that chambers and plates don’t allow much sonic variation—unlike digital reverb, you don’t have a plethora of presets. However, recording engineers are resourceful, and came up with several ways to alter the fundamental sound of their reverbs.

With both plates and chambers, you could equalize the sound going in or coming out of the reverb. As Abbey Road figured out, this was typically about filtering out lows. We still do this today with plugins to keep reverb from “muddying” the low frequencies. For pre-delay, tape delay was the main option until delay lines came into being. Of course, tape had its own subtle idiosyncrasies like wow and flutter, which ended up embedding itself in the reverb as well. Abbey Road wasn’t content with that, however, so the S.T.E.E.D. system was created for a far more complex and animated reverb sound than simply pulling delayed sound from a tape recorder’s playback head while the tape was running. (Vary a short S.T.E.E.D. delay time with the Abbey Road Chambers and you’ll hear some great flanging effects.)

Abbey Road’s chambers offered quite a few sound-altering options: changing the speaker placement and type, mic placement and type and mic separation. Additionally, moveable pillars helped break up reflections and diffuse the sound.

Abbey Road Chambers

Abbey Road Chambers

In Chamber 2 from Abbey Road Chambers, the pillars that diffused sound are shown in the upper center of the plugin’s graphic.

Abbey Road had three reverb chambers, two of which were similar. Abbey Road Chambers models Chamber 2, the reverb chamber most often associated with the Abbey Road sound, as well as the bright, highly reflective Mirror chamber. A stone-lined room from Olympic Studios, which at one point was a sister studio to Abbey Road, completes the roster of chambers.

The Mirror chamber from Abbey Road is on the left, and the Stone room from Olympic Studios on the right.

Ear Training

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’ve been hearing sounds from even before we were born. 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.

I was taken aback at how much both the Abbey Road Plates and Chambers nailed their respective sounds, so let’s explore how they fit into a mix. But there’s a personal bias alert; I fell in love with plate reverbs and chambers back in the days when tape ruled the world. It’s impossible for me to say one is “better” than the other because both can sound glorious, and both have their uses. However, each type often gravitates towards particular applications.

Abbey Road Reverb Plates Applications

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. If I was recording a dreamy chanteuse, the plate would win hands down. 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. With drums, I wouldn’t use a plate as the only reverb. But 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, I like doing 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.

Each example is 8 measures long and alternates between two measures dry, two measures processed.

The vocals are presented in context so you can hear how the effect of the plates is audible, even in a full mix.

Abbey Road Chamber Applications

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.

Each example is 8 measures long, and alternates between two measures dry, two measures processed.

Stone Drums shows how even a tiny bit of reverb can wrap ambiance around drums.

Decisions, Decisions…

Although I’ve accumulated quite a few reverb plugins and hardware units over the years, nothing is like Abbey Road Chambers—it really does resurrect “that” sound. When I used it on some rock drums that already had what I thought was a decent reverb sound, it was a bit of a shock. The drums not only had reverb, they had character, and an authentic vibe that conveyed the acoustic sound of a room. Yet the Abbey Road Reverb Plates has its merits too. They’re exceptionally smooth, and it’s the extras that make a difference: four plates to choose from, and controls for drive, analog, crosstalk and damping. This makes it possible to obtain both “idealized” and vintage plate sounds.

If I had to choose just one or the other, it would be tough. That’s not only because each has its own unique attributes, but whether by accident or design, they also work well together. Ever since I first put audio into a physical reverb chamber or plate, I’ve lusted after being able to add both types of reverb effects to my projects. It took 50 years...but I can finally say “mission accomplished.”

Want more on mixing Abbey Road sounds? Check out tips for mixing and producing 60s sounds.

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