The science of reverb springs

[Rob & Heather Williams]

Hi folks,

Does anyone know if the impedance is the same for all reverb
springs?  I've played around with them on the bench and I
guess you cannot insert a signal into them without
pre-amping it up fairly high, then when it comes out the
other side it is ready for amplification again.  So I
imagine it drops quite a bit going through the spring.

Other than that, does anyone know of any information on the
internet which discusses the science of reverb springs and
what actually happens to create the reverb effect?

Robert