Busker Organ Conversion to MIDI

by Steve Bowman

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Busker Organ Conversion to MIDI
As a thank you gift for an extensive tuning job, my friend, J.F. Waynick, gave me a John Smith busker organ he had built several years ago when he was in his late 80's, He told me that he wanted me to "finish it" for him.

Waynick had built it basically according to the John Smith's busker plans. After completing the initial construction, however, he decided to remove the roll playing parts and modify it to play MIDI files. Most of the front board (except where the crankshaft is located), the right side, and the top of the pressure box were also removed to provide the needed space. Waynick filled in the gaps in the right side and the back of the organ cabinet where the lid of the pressure box had been and made a lid to go over the top of the whole organ.

He built a wooden box as a windchest to fit in the space opened up. The outside dimensions of the box are 6 5/8 inches by 10 3/8 inches by 3 5/8 inches deep. It appears he used 3/4 inch thick possibly hardwood for the bottom, 1/2 inch plywood for the sides and 3/8 inch for the top. The sides and bottom of the box were glued and screwed together. The top was gasketed and fastened on with screws. Twenty 3/8 inch holes were drilled part of the way through the bottom of the box in two staggered rows. Intersecting holes were drilled from the front side in the bottom board at right angles to the vertical holes. The holes drilled from the front were sized according to the various nipple sizes needed to accommodate the existing tubing connected to the pipes. He drilled a 7/8 inch hole in the back of the box and a larger hole aligned with it in the back of the original pressure box to provide for the air supply connection to the reservoir with 7/8 inch elbows and flexible tubing.

Twenty Peterson 150 ohm 5/8 inch electric pipe organ valves were screwed to the inside bottom of the box over the vertical holes. Wiring was fed through holes in the front of the electric valve chest and soldered to a screw terminal strip. The John Wale (J-Omega) MTP-7 midi controller board was installed on top of the lid of the box and wires run from the terminal strip to the controller board, utilizing 20 of the 32 outputs on the board. A power switch and pilot light were installed into the right side of the organ, and all were wired to the board along with a socket for an AC adapter as a power source. I now power it with a sealed lead-acid battery (six amp hour or even less should be adequate) or an auto accessory plug which can be connected to the same socket of the AC adapter.

I ordered an inexpensive USB to MIDI interface from one of many Internet sources. The MIDI OUT plug is connected to the MIDI IN socket on the controller board and the USB plug on the other end of the MIDI interface can be plugged into any type of computer device which can output a MIDI signal to a USB device from MIDI playing software. An adapter may be needed on some devices to accommodate the standard large USB plug on the MIDI interface and is necessary in my case, since I am using a Windows 8.1 tablet computer (See related article). I use VanBasco's Karaoke software to play the MIDI files. With most MIDI playing software it is necessary to go under "setup" and set the "MIDI output device" to the "USB device." Twenty-note organ MIDI files are available from many sources including Melvyn Wright. Unlike player piano roll MIDI files, there are not many free ones available. When ordering, it is necessary to indicate that the music is for the Carl Frei scale beginning with bass note F. On my tablet, I simply locate the tune I want to play in the desired folder, start cranking and click on the file to begin playing it.

I did find that noise created by the operation of the electric valves was unacceptable, so I wrapped the entire electric valve chest in felt, putting extra felt underneath it in order to reduce the noise to an acceptable level.

Although, I don't intend to change a thing at this point. If I were to do this conversion myself, I would try to come up with a plan for the nipples and tubes to connect directly to holes drilled all the way through the bottom of the valve chest, with the valves mounted over those same holes on the inside. This would eliminate the tricky drilling of the long horizontal holes to intersect the staggered short vertical holes. It might even be possible to remodel the original pressure box to be used as the valve chest for the electric valves. In that case, any valve noise might be difficult to eliminate. I would also try to run the air supply hose up the inside of the organ to the front side of the wind chest instead of going outside and up into the back.
(Why not put the windchest and valves directly underneath or behind the pipes? This eliminates all the tubing completely - MW)

Even though Mr. Waynick gave me the organ, telling me to "finish it" for him, his work on the internal MIDI parts of the organ was virtually flawless. I got it playing almost immediately after reprogramming the controller board to match the MIDI files I had obtained. Most of my time working on the organ was spent eliminating leaks and making the bellows system provide an adequate, stable air supply (See related article). I am very pleased with the results. When I played it for Mr. Waynick after finishing it, he said, "I want it back." That's all the approval I needed.

MIDI chest open

Inside MIDI chest

Tubes to pipes, wires to controller board

MIDI components connected

Connection to reservoir and battery

Completed project. The old and the new

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