Hi all,  About the spill valve system:  I don't think that it has been
ignored by the guys doing the electronic simulators, that the spill
valve actually adds positive feedback into the regulation.  I also know
that some rolls especially used the spill valve for some musical
effects.  This was done by the piano playing on accompany and the theme
levels raised or lowered but without any theme perforations.  In fact
I have discussed this and seen it mentioned a few times already.

To accurately simulate this electronically is much more difficult than
one would assume because one would need an accurate transfer function
for the complete system.  I am not sure if even Aeolian knew what that
was because there are so many variables.  Robbie might be able to tell
us more.

Regards,

Bernt Damm
Cape Town

 [ As far as I know, the editing techniques were communicated informally
 [ among the music roll editors.  An inquisitive editor might discover
 [ a method for better soft effects and then tell another editor about
 [ his tricks.  Or maybe he wouldn't.  I don't believe the engineers
 [ knew, or cared, how the editors created good music.
 [
 [ The computer emulator program, such as created by Richard Brandle
 [ for his program "Wind", should give today's music roll editor the
 [ same audio feedback as the piano which the editor used for the
 [ original roll many decades earlier.  Richard has put many hours into
 [ refining his emulators, and he provides several parameters for user
 [ adjustment.  I suspect his Duo-Art emulator considers the effect
 [ of the spill valve.  -- Robbie