harky wrote:Had anyone seen or heard of anyone making a plate reverb out of a glass pane?
I know they used to pump sound into empty rooms with movable glass walls to create verb (back in the early days) but ive found no other mention.
Keen to try it.
Generally, sheets of glass make a pretty poor 'reverb plate'.
Glass is a special type of amorphous solid which lacks the uniform long form crystaline structure of metal plates so they don't 'ring' or resonate in the same way as similar metal structures. The internal structure of glass tends to damp the kinds of resonant behaviour found in metal.
It's possible to make glass objects which do ring, e.g lead crystal bowls or drinks glasses, or even glass "bells" such as those used in a glass harmonica but not in a way that would work like a reverb plate. Resonant glass objects tend to have a very narrow bandwith within which they resonate - more of a ping or whistle than a woosh - and sheets of glass generally damp all but a very few frequencies carried though them. As ManFromGlass said, they make more effective filters than resonators.
The use of glass plates in reverb chambers wasn't to exploit their own resonance, rather it was their ready availability and efficiency as wide bandwidth and relatively inert reflectors with very low absorption co-efficients which kept the sound energy bouncing around in the space with minimal losses. By adjusting the number and geometries of the reflectors within the chamber, the character and duration of the reverb in the chamber could to an extent be varied and controlled.