On Terry Smythe's dilemma of what to do with his Angelus player: It's
true that the two systems are related.  The Angelus "snakebite" theme
holes are in the same positions on the roll.  Back in early '70s when
I first got my Duo-Art, I had about six good Angelus rolls that I would
play in "Themodist" style, running the dynamics with the hand levers.

Which leads to my next statement, that Angelus rolls should be out there.
I traded those 6 rolls for D-As, but they should be out there somewhere.

According to White's little book "Piano Playing Mechanisms", the Angelus
action is "digital" like the D-A but with two important differences.
First, it uses Ampico-B type concept of using the expression codings from
the roll to establish a "reference vacuum" which then controls the main
suction to the stack.  It should be faster than the D-A, as well as
simpler and more reliable.

Second, the Theme and Accompaniment are connected in series -- the Accomp
works from the Theme's output, so the Accomp is a given fraction of the
Theme level, not of the pump suction.  Thus for a given fixed Accomp
level, it will "ride" up and down with Theme dynamics.  By clever coding
of both sides, many Accomp levels can be had.

I think there are 5 holes (32 levels) of Theme and 3 holes (8 levels)
of Accomp (relative to the Theme level).

In short, I would not modify this rare and excellent system into a
relatively common type.  And by the time you had acquired or made the
Duo-Art components to do the conversion, you could have converted an
88-note player to D-A.

Also, where is the stack division point of the Angelus compared to the
D-A?

By the Way, I own a D-A, currently getting it re-rebuilt, but an Angelus
would be really special.  Find a new owner who *does* appreciate it.

Best wishes, Mike Knudsen