Reverb springs - different shape different sound

[Electro-Voice 664]

Has anyone heard of a reverb unit that uses a customized spring? I was thinking about sound waves and it got me thinking about the shape of reverb springs. Like; would a spring that got wider on one end have a unique decay? Would a squared spring sound different than a round one? A tight coil that loosens in a section? Etc etc.
Anyway, just wanted to hear your thoughts, or experience

[blackdiscoball]

Im sure it would Im pretty sure the better reverb units use multiply (normally 3) different size/tensioned springs so they all vibrate differently so as to have a more well rounded sound, so knowing that any changes would make a difference in the sound. THough I imagine the gauge of the spring would effect it more then whether its square or round.