Craig Brougher said:

> Duo-Art has sixteen different levels of expression, while Ampico
> has only seven.  However, Duo-Art normally didn't use real-time "on
> the fly" expression, either.  So for the most part, Duo-Art was a
> binary changing machine.  That was ok, since the finest musicians can
> only detect about seven or eight discrete expression levels, anyway.
> (I realize we think we are much better than that).  But the stuff in
> the music that really makes the difference is the phrasing and
> pedaling.  That takes an instrument that has been thoroughly
> fine-honed and fussed over for weeks!  You do _not_ achieve that
> in a couple of hours of adjusting.

I've never seen any theorizing about the Duo-Art that takes proper
account of the exponential delays that in fact take place in the suction
level changes, and are significant once the level change is more than say
5 or 6.  It takes something like a third of a second for a fresh level to
be established, against Ampico's 0.1 second.  So all the fast coding in
Duo-Art rolls has to compensate for this by dotting in higher or lower
levels than are strictly needed, just to get a steeper slope.

So in theory you could code Duo-Art rolls to have more than 16 levels,
or 32 with theme, although in practice if you wanted to do this, delaying
the snakebites two or three advances gives you a much more controllable
"half step down".

This peculiarity of the Duo-Art was unfortunately flouted by Gordon Iles
in his creation of Gerald Stonehill's Vorsetzer robot in the 1970s -- he
gave it Ampico valves, and even claimed that fidelity to the rolls would
be better!  The result on the latest Nimbus CDs which use this machine is
that, while many rolls are reproduced well, those with fast passagework
come out crude, lumpy and unconvincing -- an enormous shame, as it has
given critics of the reproducing piano an apparently respectable
platform.

I've heard comparison recordings of this and traditional Duo-Arts playing
the same roll and the difference is astonishing.  Nimbus executives must
have cloth ears: at one presentation we were invited to guess whether a
Debussy piece was roll or pianist.  It was embarrassingly rough and
obviously the robot at work on a superb piano.  (Or maybe they employ
really skilled pianists to mimic it ?)

Dan Wilson

 [ Artis Wodehouse emphasizes how fortunate she is to work with her CD
 [ producer at Nonesuch Records, who _can_ hear the differences and
 [ supports her efforts to present a favorable (if perhaps not always
 [ faithful) portrayal of music from music rolls.  -- Robbie