Plate Reverb

The History of Plate Reverb

In 1957, EMT, a pioneering German company, invented and built the first plate reverb, EMT 140. This model had large proportions (8ft * 4ft) and weighed over a quarter of a ton. These original units were quite large and expensive but still cheaper than building a reverb chamber. You can hear the sound of this device on countless hit records from the 1960s and 1970s. While the mobility of plate reverbs was not an asset, they had better sonic qualities than spring reverbs that came before them.

Furthermore, the EMT 140 sound does not resemble the true natural reverb. It sounded slightly metallic. However, it blended with any instrument, especially the vocals. The bright, dense, and smooth sound of plate reverbs also made them a likely choice for drums.  

Sonic Complexity

Plate reverb is a type of audio processor that has a unique design. It offers a sonic complexity compared to reverb effects that came before plate reverb. This means that plate reverb consists of a large plate of metal that vibrates in a two-dimensional way, down the length and across the width of the sheet of steel. An audio signal feeds a driver connected directly to the plate, causing it to vibrate. The presence of a plate reverb is unmistakable, but we can also notice that it doesn't sound like a concert hall or cathedral. Plate reverbs have a distinct sonic coloration, which modifies the timbre of the instruments. This mechanical system offers a unique, strongly flavored sort of resonance. While its automated technology is hardly cutting-edge, like most modern reverb effects, its sound is still relevant and used in current productions.  

Plate's Flexibility

Because the plate is excited with blending waves, not compression waves, the propagation speed is determined by the elasticity and mass distribution of the plate and by the plate's thickness and suspended tension. Plate reverbs can, therefore, slow the propagation speed down to one thousand times the speed of sound in the air. A mechanical device much smaller than a hall can generate a reverberation similar in duration to that of an enormous hall. Also, plate reverbs offer further advantages, like applying various means of damping. A good example would be placing liquids or porous materials against the plate. These modifications adjust reverb time across the valuable range, offering the sound engineer highly desired production flexibility.

Lastly, when sound is transferred through metal, high frequencies travel faster than low frequencies. This more-less happens in all mediums, but especially in metal. In a plate, the high frequencies arrive first, and the lower frequencies come slightly later. This is very important when understanding why a plate reverb may be a better or worse choice than a natural space.