Art,  Your description of the Imhof & Mukle orchestrion barrel rotation
speed is indeed fascinating; I had no idea it could be controlled in
that manner.  I'd think it would be difficult to regulate the slower
speed by simply increasing friction.  Is there a significant transition
time as the air-brakes speed up and slow down?

I assume there's some way to regulate the slower speed -- any idea what
percentage the slow speed is in comparison to the fast?  Certainly an
interesting way to get the most out of a barrel, and without complicating
its basic drive method!

Thanks,
Todd Augsburger - Roller Organs
http://www.rollerorgans.com/

 [ Art says brake pads are pressed against friction wheels on each
 [ of the two air-brake fan shafts.  This seems similar to the speed
 [ control of a phonograph spring-motor.  The fans will continue to
 [ provide modest speed regulation.  -- Robbie