[sdiy] transducers

[jhno]

>Remeber you want to TWIST the spring, not shake it end to end.

there is a third axis of excitation - compressing and decompressing the
spring. my understanding is that it is the complexity of these three
interacting modes of resonance that makes spring reverbs difficult to model
digitally.

i suppose the excitation techniques i describe are 'messy' in that they do
not attempt to isolate one axis of motion. i have coupled a speaker coil to
a spring so that it twists the spring by applying tangental force - but
obviously, this is going to push laterally as well, and to a lesser degree,
longitudinally.

if anybody can point to spring model that is complete enough to describe
all this, i would love to see it. then instead of haphazardly ignoring
elements of the system, i could authoritatively ignore them.

jhno


(actually i have messed with excitation of a long, straight, taut wire more
than springs... very nice delay and resonance effects... negligible torsion)