Gear Geek: EMT 140 Plate Reverb

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Housed in a soundproof wood-and-steel box, the EMT 140''s plate was a metal sheet only half a millimeter thick.

With the advent of convolution reverb, some would say that nobody needs a real plate reverb anymore. Not surprisingly, many purists disagree. EMT''s 140 was the first, indisputably changing the sound of recorded music the moment it appeared in 1957. The 140''s smooth, complex reverberation is still very much in demand, but you no longer need a wood-and-steel box weighing hundreds of pounds and measuring 8 x 4 x 1 feet to get it. Arguably, convolution reverb duplicates plate reverb quite precisely and makes it possible to tailor the effect in ways you never could with the real thing.

Before Walter Kuhl designed the 140 for Elektromesstechnik (EMT), authentic-sounding reverb required a lot more space. Typically, a studio''s so-called reverb chamber was an acoustically reflective room with a speaker at one end and a microphone at the other. The walls were often layered with plaster to increase reflectivity and reduce standing waves. Sound from the speaker bounced off the walls and was picked up by the mic, then mixed with the original signal. If a studio couldn''t afford the space to dedicate a room for reverb, an empty stairwell or tiled bathroom often sufficed.

Putting reverb in a soundproof box like the 140 not only saved space, but it also gave recording engineers greater control over its sound. Inside the box was a big metal sheet—the plate in plate reverb—only half a millimeter thick, suspended by clips attached to a rigid frame. In the original 140, a tube-amplified driver resembling a loudspeaker coil vibrated the plate, and a piezoelectric pickup captured the vibrations from the plate''s edge.

Compared with traditional reverb chambers, the 140 offered better low-frequency response and used very little electric power. It also let you attenuate high frequencies separately from low frequencies for a wider range of natural-sounding effects. The 140 used a pad made of porous materials to damp the plate by absorbing its reflections. Just as a piano''s soft pedal activates a felt strip to damp the strings and thus shorten decay time, the 140''s damping pad governed its decay via a remote-controlled servomotor, which changed the pad''s proximity to the plate.

The first 140s were mono, which makes perfect sense when you consider that stereo records weren''t available until 1958 and stereo radio didn''t exist until three years later. EMT later manufactured stereo versions and eventually replaced the tube amp with a quieter, more dependable solid-state circuit.

Today, you have many virtual alternatives to owning a real EMT 140. Sampled 140s are available for practically every convolution platform. Audio Ease Altiverb users can download free impulse responses from units used by Elvis Presley and Wendy Carlos. Perhaps the best emulation yet is for Universal Audio''s DSP platform; the UAD EMT 140 plug-in delivers superior control and versatility while preserving the sound of the original.

Former EM senior editor Geary Yelton lives in Asheville, N.C., surrounded by beautiful mountains and wonderful toys.