Modifying and Repairing the OSI Strasse Orgel

These short notes describe problems and changes I have either made or heard about from others. If you have made changes to an OSI Strasse Orgel, please send me a note describing your work so I can pass it along to others.

Swollen Front

The lower front panel was constructed as a single glued-up piece. Humidity caused these panels to swell, increasing the width by up to 3/8 inch. The close-up photo below is taken from behind at the catch end. In some cases the panels warped as well. According to Paul Fischer, in a few cases OSI inserted braces into the back of the panel. Our case front stayed flat, with the only issue being exposed unfinished wood, so we just lived with it. I did have to move the part of the latch installed on the door. My new lower panel described below addresses the issue.

Rough Plexiglass

The plexiglass panel inside our organ had rough, saw-cut, edges. Paul Fischer said this was also an indication that it is an early organ, and that these were smoothed on later organs. In some cases, early organs had wires abraded on the panel edge. I used sandpaper to round and smooth the edges.


The Strasse Orgel was supplied without handles, although they were an option priced at about $35, installed. Most owners have added some form. I installed brass "screen door" handles from a home center which cost about $3.50. Without them, loading and unloading the organ from the car would be difficult.

"Fixing" the Top Panel

The first change I made to our OSI Strasse Orgel case was to modify the top to accommodate the Combo ReadeR electronic unit.

The original two-piece top worked reasonably well with the MPV-4000 electronic control unit, although it was a bit of a bother to disconnect the top brace to access things.

The Combo ReadeR electronic unit has its display on the top face, and if placed on the plexiglass shelf, it can not be viewed easily with the original top.

I removed the original top and cut the larger panel in two using a table saw. Note that the panel should not be cut in half, but the rear portion should be about 3/4 inch wider than the front in order to allow the top to angle properly. This is because the original piano hinge is located at the top surface.

I installed a hook-and-eye to hold the top open, but allow it to be closed easily.

I installed two brass hinges in rabbets (recesses) as shown below.

I added a 1/4 by 1/2 inch strip of plastic to the front in order to allow the shelf to be used to display CDs and other items. The photo shows the strip before I painted it with brown paint and secured it in place with small brass screws.

Modifying the Front Panels

Since the organ belongs to Norma and I don't want to make changes without her approval, my changes to the front were done as new work, with the original panels being retained in case she want to reverse my modifications.

My new upper panel was made from a poplar 1 by 3 purchased from Lowes®. I used a planer to reduce the thickness to match the original panel. Since the original curved front was about 3 1/2 inches wide at the ends, I left the lower edge straight so that the center width would be adequate. I made new end blocks to match the originals.

I made the lower "gold" trim strip from some 3/8" poplar with a rounded edge which I had in hand, and painted it with crafter's paint. The letters are die (or possible laser) cut plywood from a craft store.

Since Norma was unsure about how she would like to decorate the lower panel, I made it as a "framed panel" with a removable plywood center. I used poplar from Lowes, and used mortice-and-tenon construction.

The "painting" on the insert shown in the photos was created in PaintShop® and decoupaged in place using
polyurethane semi-gloss finish. I had used decoupage decorations on my Smith Senior 20, but in that case I used the water-based ModgePodge® medium. If you decide to try this type of decoration, be sure to run a test to make sure that your "varnish" does not dissolve your printer's inks and cause bleeding.

I went through a number of experiments in trying to matching the original finish. My final process was to color some polyurethane semi-gloss finish with wiping stain. This created a semi-transparent color similar to the spray used by OSI, and by adding several coats I could adjust the color density.

I'll add photos of this as soon as the varnish is dry and the panels are installed.

Fixing the Lower Link Ball-Joint

In July 2011 the lower ball-joint on the bellows drive popped off. I found that the ball-stud was loose, allowing the stud to rotate too far and nudge the socket off. (When I made the repair, I found the hole was actually elongated.) I was able to reach down through the plastic panel and tighten the stud, but it started working loose again. It was at that time that I met Paul Fischer. He observed that the stud was mounted in a wooden piece, and said that it was evidence that we had an early organ, and that a metal bar was used in most of the organs.

I had already decided that the wood should be replaced with metal. Following Paul's outline of the dis-assembly process (
Inside the OSI Strasse Orgel), I installed a new mount made from a 4 inch piece of 1/4" by 3/4" aluminum bar. I threaded the stud mount to match the stud (it was a metric thread) and use the original nut to lock the stud in place. The original wood screw spacing was copied, and I used the original screws.

Tuning the OSI Organ

I have not needed to do any tuning on our organ.

The organ is tuned to a Carl Frei 20 note scale. It is pitched the same as most Raffin 20er and John Smith Busker organs, with the lowest note being MIDI No. 53. Most of the organs will be tuned to a "well tempered" scale with an electronic tuner, but a true scale in Bb or F might be chosen as a better-sounding alternate.

Given that most small MIDI output boards have 32 notes available, if the OSI organ had been designed from scratch, a 22, 26 or 31 note scale might have been chosen, but the organ was based on the Hofbauer 20 Mikro which was in turn derived from a Hofbauer 20er roll playing organ. Given the proprietary electronics, availability of music was probably not a serious issue.

Paul says that if the "cork seals" on the tuning plugs on the brass pipes have a tendency to slip, add a little  silicone sealant at the top of the plugs after tuning.

Paul also said that if the tuning plugs on a Hofbauer 20 note organ get pushed down too far, the solution is to break the pipes loose and push the plugs up from the bottom. He did not say so, but I assume the same would apply to the OSI. Some of our pipes have come loose from the epoxy holding them in place.

Some other owners have had to address tuning issues and report that an unexpected number of socket wrench sizes are required to fit the nuts.

Some of our pipes are "a bit loose." The epoxy used by OSI does not stick completely to the tubes, possibly because of a wax or lacquer finish used to keep them bright. Our loose pipes have not fallen out, and I have just straightened them as necessary. I had thought of sticking them in place with a drop of PVAE glue (Player Piano Supply's "Plastic Adhesive" or "Aileen's Tacky Glue") and when I discussed the issue with Dave Wasson he suggested the same fix.

I lifted out one of the pipes and noted that there is a screw head on the bottom of the plug. It may be useful to remove the pipe to access this screw to loosen or tighten the plug. With the pipe loose, it can be tuned, then the plug tightened with screwdriver and wrench, then replaced with a tight plug.

Fancy Paint Jobs

A number of owners have had beautiful German style decorations added to their organs by local artists. This is particularly effective on the black painted cases.

Regardless of the origin of the OSI design, I prefer to think of our organ as a late 20th Century American product, and to use decorations reflecting that.

Links to additional OSI Street Organ information:
My main Mechanical Music page