that unique plate reverb sound

Unlike digital reverberation, the plate reverb is one of the true analog attempts in recreating convincing reverberation build right into a studio device. It is basically an electro-mechanical device containing a plate of steel, a transducer and contact microphone(s) to pickup the induced vibrations from that plate.

The sound is basically determined by the physical properties of the plate and its mechanical damping. Its not about reflecting waves from the plates surface but about the propagation of waves within the plate. While the plate itself has a fixed, regular shaped size and can be seen as a flat (two dimensional) room itself it actually does not produce early reflection patterns as we are used to from real rooms with solid walls. In fact there are no such reflections distinguishable by human hearing. On the other hand there appears to be a rather instant onset and the reverb build-up has a very high modal density already.

Also reverb diffusion appears to be quite unique within the plate. The wave propagation through metal performs different compared to air (e.g. speed/frequency wise) and also the plate itself – being a rather regular shape with a uniform surface and material – defines the sound. This typically results in a very uniform reverb tail although the higher frequencies tend to resonate a little bit more. Also due to the physics and the damping of the plate, we usually do not see hear very long decay times.

All in all, the fast and consistent reverb build up combined with its distinct tonality defines that specific plate reverb sound and explains why it is still so much beloved even after decades. The lack of early reflections can be easily compensated for just by adding some upfront delay lines to improve stereo localization if a mix demands it. The other way around, the plate reverb makes a perfect companion for all kinds of delay effects.