Re: Something for Pittsburgh

hey Alan,

i never had any trouble with the contacts, and i've
owned one or more C-vox's at all times since i was
in my mid teen's... this one has been idle for at least
5 years now and was gnarly for the first 5 minutes
but it's been fine since i've hit all the keys bunches.

the contacts are a conical spring, contacting a thick
common buss bar

the conical spring is flexible enough to wrap slightly,
so there is more than 1 point of contact... this is the system
that Bob Moog used in the units i owned from early synth days
too, and i never had a problem with them either - though i finally
passed them along to a younger musician in the late 1990's

the wraparound causes electrical "bounce" which some digital
circuits on early retrofit kits had a hard time with, but
on the high voltage Lowrey circuits was not a problem

this new MIDI seems to have no problem handling the bounce

the one caveat with conicals... you have to be quick and careful when
you solder them in

there were some wire contact methods with a very limited contact area,
and so more potential for misfired notes... the Duovox may have this
problem, i'll see once it's wired up... it uses stiffer silvered wires

i have a can full of contacts with carbon points too, on leaf switches
that i thought might work well, but never got around to needing

glass reed magnetics eliminate bounce pretty well, and never
ever tarnish as they are in a vacuum... i have a bunch but i've
never put them into anything (yet) Master was converting to these
in their higher priced stuff last i knew, but i don't know how
far they committed to these before he shut down the installs

hall effect transistors also use magnets to trigger, they
are solid state but require more circuitry

opticals have been used by some systems, but again
a lot of extra circuitry plus possible problems in certain
lighting conditions plus dirt

and moderm Synth keys use the "top hats" or a variant
which i've described in detail on the Roland board

i think the conical springs are very reliable and long lived,
and if the simpler technology can be used, sometimes
it's the better choice, though perhaps not the most elegant

finally, on any Organ Accordions or Synths, i've never seen any
contact corrosion in any well done design that wasn't caused
by sweat

now a stupid design could mave metal migration in some conditions

and cheap contract manufacturing of subsystems can leave
considerable chlorides on circuitboards in assemblies
that are made by companies who really don't give a crap

corrosion in those cases is by carelessness or design, not a
byproduct of some weakness in the contact itself

Ciao

Ventura
.

Relevant Pages

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