The Nelson-Wiggen also used a switch to low vacuum for snare drum
expression, for example.   The "hammer rail" xylophone rest rail worked
like a piano soft pedal, but low vacuum was the principal expressive
control.

I've never heard tambourine/castanets in a Seeburg KT which have the
expression _range_ that a snare drum has in a Nelson-Wiggen 4x, 5X, 6
or 7.  And for good reason: the margin of vacuum adjustment is greater
in Nelson-Wiggen instruments than in Seeburgs.  Don't blame me -- it's
just the physics of designs that make the difference, assuming both
systems are properly rebuilt and regulated.

Hasn't anyone ever done a comparison in vacuum levels between the
dynamic levels in reproducing pianos?  Now there's a good time-wasting
project: compare the high vac/low vac levels of expression in rebuilt
orchestrions.

Cheers,

Stephen Kent Goodman