[ Editor's Note:  This letter from Horst Mohr is forwarded here
 [ to us via Robbie Rhodes.  I can only dream of writing in another
 [ language as well as H.M. writes in English.  I encourage him to
 [ send additional postings here directly!
 [ Jody

Date: Sun, 14 Jan 96 22:50:47 PST
From: rhodes (Robbie Rhodes)
de: rhodes

Subject: Further Introduction of Horst Mohr (fwd)

Herr Mohr is amazing -- where does his energy come from???

"Koelner Dom" is the marvelous big cathedral by the train station in Cologne.
It was damaged during the war, but is now almost completely restored.

"Aufzug" is a procession or parade.  It also means "elevator" or "lift",
thus the dual connotation of "Aufzugmusik"!

Horst responds here to my questions concerning

        Translation of his technical articles
        Who cuts the slots in the marked paper?

-- Robbie Rhodes

===== forwarded message follows ======

Subject:   some facts

Hi Robbie,

you are right, I am a bit anxious to write directly to the group,
as I am an old chap and learned English half a century ago at school.
Seldom was there opportunity to brush it up, except reading manuals or
technical advices and computer magazines, as there were no German
ones in the early 80ies. I'd rather write to you first and let you
edit the stuff, else tell me if I should mail automatic-music@foxtail.com
or rollreq@foxtail.com ? Just edit and forward it when you want. If I
should write something not to public, I'll mention it.

First to your question: The rolls are conventionally punched by hand of
Dr. Hocker. The printing is just a b/w picture of the roll (on "endless"
broad paper) with the edges printed as lines. As I play the MIDI data from
my first computer to the second one before, recording them in the program
which then does the printing, also the timing (position of the printings
on each point of the roll) will be right.

I was always interested in electronic music and did much experimenting.
Also built some el. organs (kits) and added my own ideas to them (1960/70).
After reading "Byte Book of Musik" (1979 or so, read it, you'll be amazed!)
and Hal Chamberlin's "Musical Applications on Microprocessors", and before
MIDI was invented, I built a 8 voice organ synth for my CP/M computer which
could play music, that I wrote with a normal ASCII editor before. I published
that later in the German computer journal "mc" June 1986.

1985, after a public demo with an organ trio sonata of J.S.Bach I was
introduced to Dr. Hocker, who owns a couple of reproducing pianos. I was very
impressed by his collection, we agreed to collaborate but lost contact.

For the International Computer Music Congress 1988 in Cologne (ICMC)
I built and programmed the "Aufzugsmusik" in commission for Clarence
Barlow. The opening festival was in the restaurant of a tv tower, in a
height of 160 m. A little model of the "Koelner Dom" on a letter balance
changed weight with the going of the elevator and via a postcard sized single
board computer that I programmed, produced a kind of music. "Aufzugmusik"
is a German term in the opera, but can also name music in a elevator.
A typical joke of Clarence Barlow.

On this occasion I was introduced to Wolfgang Heisig. For him I constructed,
built and programmed the "Phonolith", an interactive music sculpture.(Das
Mechanische Musikinstrument Nr. 58. Juli 1993 p.42).

1989 by fortune I met Dr. Hocker on a Stockhausen concert again and a
cooperation began. He lend me the part of a Hupfeld piano with the roll
mechanism, the wind motor, the tracking pouches and dozens of Ampico A
rolls. And last not least the technical information and his broad knowledge
of the subject.

At first I used my motorcar's vacuum cleaner for regulated air power. Later
I used stepper motors. The roll ran at first over a light tube, fed by
regulated DC. Later I used infrared LEDs. Finished 1990, but still improving.
In June 1992, after visiting me, Dr. van den Hoogen published his impressions
in the German journal for home recording and computers, "KEYBOARDS".

Until 1994 the controlling computer was a 386/33, since 1995 a 586/90.

Yesterday I played Rachmaninoff and others via the notebook computer of Dr. Hocker
on the Yamaha Disklavier grand of Rolf Jacobi, a great collector in Cologne.
Do you suppose what he liked best ? It was your Brasilian Maple Leaf and
he wants a roll of it for one of his numerous pianos. In fact it sounded
really good, though it had not "the boom in the bass" like when played on
my equipment. But a piano is a piano...

I hope i could assure you that you are handling facts editing my writings.
Please let me know how to address further.  How you want it, it's o.k.

Best regards, h. m.¶
--¶
mohr@nemeter.dinoco.DE  H. Mohr Koelnerstr.49 51515 Kuerten 02268/1561