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Abbey Road Studios’ Reverb Plate Room

Feb 02, 2016

For the Beatles, Pink Floyd, Radiohead and many others, the reverb plates at Abbey Road Studios – now modeled by Waves – have been invaluable. Read about their history and the technology behind them.

One of the unique tools available to artists recording at Abbey Road Studios in the mid-twentieth century was access to the studios’ three echo chambers for the creation of unique reverb effects. The sound created by the chambers was very natural, but not easily adjustable, allowing only a single fixed reverb and decay time per chamber. With just three chambers existing to facilitate reverb for all of Abbey Road’s recording, remix and transfer rooms, availability would often also be an issue. To combat this, in 1957, Abbey Road Studios purchased four brand new state-of-the-art plate reverb units to complement the existing chambers.

The four reverb plates at Abbey Road Studios

Designed in Germany, these were the first professional electro-mechanical artificial reverb units made available to studios worldwide. At 8 feet long, 4 feet tall and 1 foot wide, these plates were considerably more compact than the chamber rooms. Each plate contained a large sheet (or “plate”) of steel suspended vertically by a set of springs to allow it to resonate, and was fixed to a stable steel frame. A small transducer speaker was fixed to the plate’s center point, and when a signal was played through the speaker, the plate would begin to vibrate, sustaining the tone for several seconds. Two pickups were attached to each plate, on both sides of the speaker, a quarter of the distance from the plate’s edge. The pickups sensed the vibration, converted it to a line level, and sent it to the output plate amplifier.

Unlike the reverb chambers, these plates had a damper system that allowed adjustment of the reverb decay time. The damper system consisted of a fiberglass panel suspended parallel to the plate, which could move towards or away from the plate sheet. The damper could control variable distances, ranging from 1/8” away from the plate for a one-second reverberation time, to 2” away from the plate for a five-second decay. This system let the user tune the decay time with whatever precision was required to meet the needs of the particular recording or mixing session. Since the plates were not located inside the control room, engineers could set the damper position using a remote control system.

The reverb plates’ remote control unit at Abbey Road

To this day, Abbey Road Studios house the four reverb plates – labeled A, B, C and D. Plate D has all-valve amplifiers on both the input and output stages, consisting of E81L, E80CC and EF804ES valves. Plates A, B and C also have an all-valve amplifier on the input, but on the output stage EMI Central Research Laboratories custom-built hybrid solid-state/valve amplifiers, in an attempt to keep the noise floor to a minimum. The sound of the plates is generally considered smoother than that of an echo chamber, if not entirely natural. Most Abbey Road engineers initially preferred the more organic-sounding chambers, but this became less of an issue when bands started to experiment with psychedelic sounds and ‘natural’ sounding recording techniques were becoming less in vogue for pop music.

Due to the nature of analog valve equipment and manufacturing techniques (plus the EMI custom-built amps), no two plates sound the same: each has its own distinctive sonic characteristics. Ever since the Sgt. Pepper era in the 1960s, these four plates have seen significant use on nearly every pop recording done at Abbey Road Studios – from the Beatles and Pink Floyd to Radiohead, Adele, James Blake, Florence + the Machine and Frank Ocean. The plates even started being favored by some of the classical engineers, and before long were being used on a wealth of films scores – so much so that the plates would often have to be booked well in advance of sessions to guarantee their availability.