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MMD > Archives > June 2003 > 2003.06.19 > 10Prev  Next

Electro-pneumatic Hybrid Duo-Art Vorsetzer
By Peter Phillips

Tom Lear (MMD 0301618) has asked for the Duo-Art story I alluded to in
my previous posting.  Again it's unlikely anyone in the US will know
much about this, so hopefully you'll find it interesting.

My introduction in 1976 to the reproducing piano hobby came through
Denis Condon, who at the time wanted to build a Duo-Art Vorsetzer that
incorporated as much technology as possible.  He envisaged a device
with an electric roll drive, electrically powered pedal actuators and
electronically controlled vacuum regulators.  Denis had recently
visited Gerald Stonehill and had been inspired by "the Robot", Gerald's
Duo-Art Vorsetzer.

At the time, I had just moved house, closing down my electronics repair
business to take up a lecturing position.  I therefore had a fully
equipped, but idle workshop.  I had always been obsessed with pianos,
despite my "piano-less" childhood, so here was an opportunity to
exercise my technical skills and be involved in pianos.

So my absolute first introduction to the hobby came about through
developing an electric roll drive system to meet Denis's requirements.
It was simple yet complex.  I used a 12V VW windscreen wiper motor
coupled to a speed control circuit that could be calibrated with a
frequency counter.  Denis wanted the motor speed to be "programmable",
so he could join rolls of different speeds to form a jumbo.  It took a
bit of doing, but in the end it was so successful that I produced quite
a few roll drives for use in foot operated players.

Then came the hard bit: electrically powered pedal actuators.
It was to take a few goes before I got the size and power handling
capabilities right, but eventually I ended up with two solenoids
mounted on a frame, arranged to sit over the soft (side shift) and
sustain pedals of any piano.  The hard bit was making it operate
silently and quickly, particularly the side shift.

I developed a solenoid speed control system that gave all the
adjustments needed to control the speed and landing characteristics.
I wanted the highest travel speed with minimum thump on both up and
downstroke, with enough power to deal with the heaviest side shift.
I finally got it all working to specifications, and it went on to
prove more than capable.

Then I got diverted by my own needs as described in MMD 030617.
However, somehow I kept up the pace, as Denis still didn't have a
Vorsetzer and the local broadcaster (ABC) was getting interesting in
this machine.  There was a push to "do something" to mark the centenary
of Percy Grainger's birth, so it was into high gear.

By now it was obvious that if the Vorsetzer was ever going to be built,
I would need to do it.  Denis has an excellent knowledge of pneumatics
(and piano rolls), but as a music lecturer, his technical and practical
skills were limited.  So we moved all the bits to my garage and started
on the vacuum regulators.  The idea was to use Ampico B regulators
controlled by a number of solenoid valves.  The B regulators are very
simple, comprising a cloth membrane that covers a grid.  The membrane
positions itself to equalise the vacuum either side of the grid, which
means the vacuum is controlled by opening a hole to atmosphere.

We used 17 solenoid valves per regulator, 15 for the expression, one
for snakebite and one for loud pedal compensation.  At zero, all
solenoids were energised so they uncovered variable aperture holes.
This allowed us to independently adjust the vacuum for all 16 Duo-Art
levels and to create an "expression curve".  I'm not sure if we ever
got this curve right, as the Duo-Art is by now means a straightforward

With all the bits now working, I then built a frame out of aluminium
angle.  A colleague in Melbourne (Harold Ball) developed the fingers,
which were made from cast aluminium.  This was tricky, as the spacing
between fingers had to fit all types of pianos.  We used an Ampico
flange finger stack, mounted at a slight angle to give the best angle
of attack to the fingers.

I finally got it all together and then moved it in front of my newly
restored Ampico, so I could adjust and test it all.  But time was of
the essence.  By now the ABC had decided to use this Vorsetzer (sight
unseen and unheard) to make a recording of Percy playing the Greig
Piano Concerto accompanied by the Sydney Symphony Orchestra.

The machine was now fully functional, but it had no clothes.  Too bad,
as the piano removalists were knocking on the door to take it to the
recording studio.  And what a sensation it all caused! By now the rolls
had been prepared for use by deleting the orchestral accompaniment, and
also using the reroll hole to "cue" the roll for each piano entry.  The
idea was that Percy would start playing when a remotely held pushbutton
was pressed in accordance with the conductor's baton.  At the end of
the piano part, the roll would then silently advance to the next entry,
awaiting a button press to continue.

John Hopkins was the conductor (a Grainger interpreter), and the
orchestra had no idea what was about to happen.  We had set up the
Vorsetzer in front of the Steinway before the orchestra members filed
in, so when John indicated the orchestra was "going to accompany a
deceased pianist", there were many strange looks.

During the cadenza in the first movement, quite a few orchestra members
left their desks and came over to watch the machine play, scuttling
back for the last few bars.  At the end of the movement, the entire
orchestra clapped, and it was clear they were now on side.  During the
next few days we rehearsed and finally recorded the concerto.  The
local press was highly interested, and for a while Denis and I were

We then performed the piece at the Sydney Opera House (1978) in a live
broadcast around the country.  You can imagine my feelings as I stood
offstage during the performance, fully aware of just how many things
could go wrong.  A friend who owned one of the few VCRs in existence
at the time recorded the concert, resulting in a video that is now
extremely precious.

When the record was launched at the Sydney Opera House, it was such
a big deal that the vice-president of RCA came out from the US.  The
record was released in the US and the UK, and won awards in the US.
It was also released here (of course), and made the ABC a lot of money.
I was paid $200!  It was the first internationally released record made
by the SSO, so in a way we helped put this excellent orchestra on the
world map.

We went on to tour Australia and New Zealand, and to record the
Tschaikowsky PC with the Melbourne Symphony Orchestra.  These rolls
were produced by Aeolian for promotional purposes and were never
released.  If the Greig was difficult to do, the Tschaikowsky was
almost impossible.  We only ever performed the first movement live,
as the rest was just so tricky.

All of the above occurred between the years 1976 and 1982.  The
Vorsetzer is no longer, as Denis soon realised that he could not
service or fix it without me.  The frame now supports the workings of
Denis's Ampico Vorsetzer (entirely pneumatic), and the electronics is
in boxes in my garage.

I've glossed over some of the technical aspects, such as how the roll
expression actually controlled the vacuum regulators, how we set it
up, all sorts of things.  It doesn't matter now, as it's all gone.
But what remains is a recording of Grainger's interpretation of the
Greig PC, coupled with a premium orchestra.

I recently started stirring the ABC to release this recording on CD,
as there is no other similar recording (as far as I know).  It seems
the ABC cannot find the master tapes, and we have been told quite
firmly that it would cost too much to ever do it again.

I'm not sure of the copyright implications, but I intend producing
my own CD of the work from an unplayed vinyl pressing made for the
UK market.  The sound is not as impressive as today's recordings,
but Percy's playing is well captured.  If I can gain some sort of
clearance, I may be able to supply the CD to interested collectors.

I'm also very pleased to have at last told this story.  It's only one
small part of the history of the reproducing piano, but one that can
now reside in the MMD archives for others to read.  It was a wonderful
experience for me; working with orchestras, recording studios and
giving many live performances with the machine playing on some pretty
strange pianos in all sorts of venues.

Peter Phillips
Padstow, NSW, Australia

(Message sent Fri 20 Jun 2003, 06:01:01 GMT, from time zone GMT+1000.)

Key Words in Subject:  Duo-Art, Electro-pneumatic, Hybrid, Vorsetzer

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