My MIDI / Schober Project
This is a non-commercial project. Neither
the hardware nor the software design is intended to be sold. It is copyright
(C) 2002-2007 by Peter A. Stark, but you have permission to use any of
this information for your own use. You also have my permission to distribute
this information to others, with the condition that you retain this copyright
notice with all copies so distributed. You may include this design and
information in any other projects, with the conditions that any such projects
also retain the same copyright notice, and that you grant to others the
same rights as this copyright notice grants to you.
The information below describes my particular
organ conversion; although you are welcome to use the circuitry and
ideas herein for your own purposes, you need not do everything exactly
the same as I do. In some respects, your project may be simpler -- or more
complex -- than mine, and you may want to or have to modify things. That's
fine -- that is the great advantage of an open and fully documented system.
For example, in my organ, there are four identical encoder cards, but they
have three slightly different software variations, depending on their use.
That's strictly because I happen to have some extra hardware in my organ
and I need a little more versatility; most people using this approach would
have the same software version in each card.
For example,here's how
Bob Kinner adapted the system to his Rodgers organ.
This page was last modified on January 10, 2009.
I am converting an old Schober Theatre Organ --
a 1960's and 1970's digital musical instrument that used all discrete components
and was sold as a kit --- to a more modern 2000's-style system that uses
MIDI and digital circuits. This and the following pages describe the project
and document the hardware and software used.
My own organ conversion consists of the following;
someone duplicating this project could simplify it by eliminating the second
swell shoe, the Roland module, and some of the audio circuitry:
The following block diagram shows the basic data
flow between the various modules in my system; not shown is the audio processing
and reverb that is also part of the system.
The console cabinet, two keyboards (manuals), a pedal
keyboard, various control switches, and the organ bench.. This is all that
remains of the original Schober Theatre Organ - all other Schober circuitry
has been removed.. To this, I added a second swell shoe, plus the components
New MIDI circuitry (the boxes labelled MD-1 and MD-2
in the diagram below) that converts the keyboard, pedal, swell shoe, and
stop switch outputs to MIDI signals.
A Roland MIDI module to generate a limited number
of voices, such as a piano.
A PC-compatible computer which runs a program called
Hauptwerk, and which generates the vast majority of organ voices
Audio circuitry to provide reverberation and appropriate
audio processing, followed by amplifiers and speakers.
Click on each item below to get further information
on individual devices in the above block diagram. The MD-1 and MD-2 cards
are build-it-yourself printed circuit boards; all the info you need to
build them is given in the referenced web pages.
The photo shows how some of these components are
mounted. The picture shows three MD-1 cards on the side panel (at the top
of the photo), then one MD-1 and two MD-2 mounted below, the 8-to-1 merge
box against the rear panel (at the right of the photo), and the Roland
CM32P sound module closest to the camera. The thick colored wires (yellow,
red, blue, grey, and white) are MIDI cables; some of the thin wires to
each board are power lines from a common wall-wart, and two of the thin
wires are RS232 wires that carry velocity info from the two MD-2 cards
to two of the MD-1 cards.
As mentioned above, this is a work in progress. If
you have any questions, comments or suggestions, feel free to contact me:
email to email@example.com
to Star-K Systems web page
to Schober Orphans web page.