In 1957, the German company EMT released the 140, the first plate reverb. It was a steel plate, 2 meters by 1 meter, suspended in a wooden frame on springs. A driver (essentially a speaker voice coil) vibrated the plate, and two contact microphones picked up the vibrations. The sound was reverberant, dense, and smooth, with a decay time adjustable from 0.5 to 5 seconds via a mechanical damping pad.
The EMT 140 became the studio reverb of choice for the next three decades. Virtually every record made between 1960 and 1990 used one. Elvis Presley's vocals, Pink Floyd's drums, Fleetwood Mac's guitars, and countless other iconic sounds were processed through an EMT 140. The plate reverb is the sound of classic recorded music.
How a Plate Reverb Works
The physics of plate reverb are different from room reverb. Sound travels through a metal plate as bending waves, not as air pressure waves. Bending waves are dispersive, meaning different frequencies travel at different speeds through the plate. High frequencies travel faster than low frequencies, which spreads the sound out in time and creates a dense, smooth reverberant field without the distinct early reflections you hear in room reverb.
This dispersion is the key to the plate sound. In a room, the first few reflections arrive at distinct times and create a sense of space. On a plate, the reflections are smeared together immediately, producing a reverb that has no sense of "room" but has an incredibly smooth, thick texture. This is why plate reverb sounds great on vocals: it adds body and density without placing the singer in a specific space.
The plate's frequency response is not flat. Steel naturally emphasizes midrange frequencies and rolls off both lows and highs. This is not a flaw. It is part of the sound. The limited bandwidth prevents the reverb from interfering with the dry signal's low end and high end, which is why a plate can be used heavily without muddying a mix.
The EMT 140 vs The AKG BX-20
The two most famous plate reverbs are the EMT 140 and the AKG BX-20. They sound different because they are built differently.
The EMT 140 uses a thin steel plate (0.5 mm) with free suspension. The plate is large (2 x 1 meters) and the reverberant field is dense and smooth. The decay time is controlled by a damping pad that can be moved closer to or farther from the plate. The 140's sound is warm, thick, and slightly dark. It has a characteristic "bloom" where the reverb seems to swell up after the initial transient.
The AKG BX-20, released in the 1970s, uses a thicker plate in a more compact frame. It was designed to be smaller and more practical than the EMT 140 while maintaining plate reverb quality. The BX-20's sound is brighter and more detailed than the 140, with faster attack and less bloom. Many engineers prefer the BX-20 for drums and the 140 for vocals.
Capturing Plate Reverb IRs
Sampling a plate reverb is different from sampling a room or a digital processor. The plate is an analog mechanical system, and its behavior is slightly nonlinear. The driver that excites the plate has a frequency response that is not flat, and the plate's response changes with amplitude (higher levels produce slightly different behavior due to the plate's mechanical limits).
For our plate reverb IRs, we use the sine sweep technique but with a lower sweep level than we use for rooms. This keeps the plate in its linear operating range. We also take sweeps at multiple damping settings to capture the full range of decay times the plate can produce.
The result is a set of IRs that capture the specific sound of a specific plate. No two EMT 140s sound identical because the plates age, the suspension springs fatigue, and the damping material compresses over time. An IR of a 140 in original condition captures a sound that is increasingly rare.
Why Plates Sound Better Than Emulations
Modern plugin emulations of plate reverb are good. Valhalla Plate, UAD EMT 140, and PlateSonics all produce convincing plate-like reverb. But they do not sound exactly like a real plate, and the difference is audible in direct comparison.
The reason comes down to the physics. A real plate is a two-dimensional vibrating system with complex dispersion characteristics, edge reflections, and mechanical nonlinearities. An algorithmic emulation approximates these behaviors with delay networks and filters, but the approximation is not perfect. The density of the reverb tail, the specific way the frequency content evolves over the decay, and the subtle amplitude-dependent changes are all difficult to model accurately.
A convolution IR of a real plate captures everything, including the nonlinearities and the imperfections. That is why it sounds more like a plate than an emulation.
This is not to say emulations are not useful. They offer real-time control over decay time, pre-delay, and damping that convolution cannot provide. For mixing, where you need to adjust the reverb to fit the track, an emulation is often the more practical choice. But for capturing the exact character of a specific plate, convolution is unmatched.
Using Plate Reverb in Production
Plate reverb is versatile. Here are the contexts where it excels:
- Lead vocals: The classic application. A plate IR with 1.5 to 2.5 seconds of decay adds body and presence to a vocal without placing it in a specific room. Use a pre-delay of 20 to 40 milliseconds to separate the reverb from the dry vocal.
- Snare drum: Plate reverb on a snare creates the explosive, larger-than-life snare sound of classic rock records. A shorter plate (0.8 to 1.2 seconds) with fast attack works well.
- Acoustic guitar: A short plate adds warmth and sustain to a dry acoustic guitar recording. Keep the decay under 1.5 seconds to avoid washing out the detail.
- Strings and orchestral elements: A plate can add density to synthesized strings, making them sound more like a real ensemble. Blend it with a hall IR for the best of both worlds.
The key with plate reverb is moderation. Because plate reverb has no early reflections, it does not create a sense of space. It creates a sense of "presence" or "body." Using too much of it can make a mix sound flat and claustrophobic. Use it as a flavor, not as the only reverb in your mix.