MIDI Conversion of Three Pipe Organ Keyboards

My search for better keyboards eventually led me to consider purchasing some used pipe organ keyboards and converting them for MIDI use.  I’ve never had the opportunity to try some of the commercially available keyboards, and budget constraints relegated most of them to the ‘too expensive’ category in any event.

The three keyboards that I finally purchased were offered for sale on eBay by a pipe organ company that had removed them from an existing organ and stored them for many years.  They were in generally good condition and ready for use in a tracker action organ, but in my case needed MIDI electronics. I did clean and refinish the surfaces of the keys and replaced some of the felt which was worn and compressed.  I was especially pleased to find these keyboards because they were reversed color (black ebony naturals, cherry sharps capped with white).  For some reason, I have always been attracted to the reversed color keyboards, perhaps because the best organ I’ve ever played had reversed color keyboards.

I have almost no photos of the MIDI conversion process, perhaps because it proved to be much more difficult than I had anticipated. My intent was to use magnets and reed switches to make the MIDI conversion, but I should have taken more seriously the few comments on the Hauptwerk Forum that suggested that this might be difficult to do well.  The absence of any post showing a complete keyboard conversion using magnets and reed switches should have been a warning…

To complicate matters, I definitely wanted to include some kind of tracker touch in the conversion process (for which there were a number of helpful posts on the Hauptwerk Forum and other forums.)

For the sake of other VPO builders, I’ll briefly chronicle the initial and failed efforts that consumed a totally unreasonable amount of time and caused much, much head scratching and frustration.

My initial attempt was to use 1/4″ cylindrical magnets mounted on the rear of each key which would be near and attracted to a steel bar to provide some tracker-like resistance.  Once pressed, the magnets were to move up toward and activate a reed switch.  The tracker touch was excellent, but the magnets were in such close proximity that moving any single key would almost always activate the adjacent key as well.  I partially overcame this problem by reversing the polarity of every other magnet (to limit the building of a larger magnetic field).  This helped, but not enough and after numerous tries I decided that the 1/4″ magnets and their attraction to some steel bar or perhaps a steel screw would have to be separate from any magnets used to activate the reed switches.  First attempt: Failure.

It is worth noting that there are many possible ways to mount the reed switches and magnets which can make it very hard to determine which way is best and most reliable in any given situation.  I used a technical guide mentioned on the Hauptwerk Forum to help make decisions on how to best configure the switches and magnets.

Eventually the 1/4″ magnets were moved several inches toward the front of the keyboards, mounted on a piece of angled steel under the keyboards, and allowed to attract steel screws on the bottom of the keys.  The photo below shows this arrangement.

Magnets used for Tracker Touch

Magnets used for Tracker Touch

The screws under the keys were initially adjusted to be about 1/16″ above each magnet.  Finer adjustment could be made by simply pushing the magnets further in or out since the magnets simply sit on the steel angle iron by magnetic attraction.  I found that the polarity of every other magnet had to be reversed, otherwise the entire angle iron began to act like a huge magnet that could affect reed switches several inches away.  (This concept of reversing every other magnet would prove critical in future attempts using reed switches.)  The tracker touch from this arrangement was excellent and could be adjusted from light to heavy touch without much difficulty.  I opted to adjust them for a relatively light touch.

Having obtained the desired tracker touch, I purchased some smaller magnets (1/8″ x 1/8″ and 1/8″x1/4″) to try with the reed switches.  The smaller magnets on the rear of the keys were better, but still resulted in frequent crosstalk between the keys.  I tried a physical re-arrangement (for which I have no photos) of the magnets and switches to keep them further apart from adjacent keys.  This was workable, but needed frequent adjustments, and sometimes left me with a single note sounding continually – clearly unacceptable.  Second attempt: Failure.

At this point I decided to try an approach mentioned on more than one forum in which the magnets and reed switches are permanently located close enough to each other to keep the switch activated.  A piece of sheet metal attached to each key is positioned between the magnet and switch to interrupt the magnet field.  When the key is pressed the piece of sheet metal moves up enough to allow the magnet to re-activate the switch.

The next photo shows this arrangement.

Keying Mechanism Using Magnetic Interruption

Keying Mechanism Using Magnetic Interruption

Amazingly enough, this arrangement did work…well, sort of.  For the most part, the keying was reliable, but whenever there was crosstalk with an adjacent key, it proved to be very difficult to position the sheet metal piece to eliminate it and at the same time preserve the firing point of the key so that it was similar to other keys.  I used this arrangement for a short period of time but found it frustratingly unreliable.  Third attempt: Failure. (I do, however, think that with more work, this might be a workable system.)

I was almost ready to give up on the idea of magnets and reed switches for the keyboards and default to some mechanical electrical contact (or perhaps an optical system, or hall-effect system which many others have used successfully.)  However, I found a photo of an Allen organ keying system that was remarkably close to what I was trying to do and which had to be reliable – otherwise Allen Organ would not be using and promoting it.  There was always the possibility that Allen Organs reed switches and magnets were custom made to work together, but still, it seemed like the concept should be workable with my magnets and switches.

After some experimentation in the shop I came up with the arrangement shown below.


Working Magnetic Keying Arrangement

Each 1/8″x 1/4″ magnet is located just below the corresponding reed switch and is isolated from the adjacent magnet by the metal ‘tabs’ on either side.  The screw nearest the switch allows for fine adjustment of the magnet up or down to set the firing point for each key.  The polarity of the magnets are all the same (but read further below…)

Each keyboard proved to be easily adjustable for the firing points, and 100% reliable in use.  Reliable, that is, until I put the entire keyboard stack back together.  When the keyboards were stacked the firing points changed unpredictably, and worse yet, some keys were likely to sound continually – a completely unacceptable situation.

Prior attempts had alerted me to the possibility that when the keyboards were stacked there could be some magnetic interaction between the keyboards because the ends of the keys are only about 1″ apart vertically.  All told, both the tracker and keying magnets were uncomfortably close to each other horizontally and vertically.

Initially I thought that the tracker magnets on the next lower keyboard might be affecting the keying magnets of the above keyboard, but a few experiments indicated that the effect between keyboards was limited to just the keying magnets.  Eventually I realized that I should reverse the polarity of all the center keyboard keying magnets to help cancel any interaction between keyboards.  This, fortunately, was completely successful and restored each keyboard to 100% reliability when stacked.  This arrangement is recent enough that I can’t judge its long-term success, but given the lessons learned from the failed attempts, I think all of the issues have been dealt with and I expect long-term stability and reliability.  Fourth attempt: Success at last!

Functional Keyboards - Finally!

Functional Keyboards – Finally!

I’ve not shown the wiring on the rear of any of these keyboards because each was nearly identical to that used on my pedalboards using Midi-Gadgets components.

Would I use magnets and reed switches again?  Had I known how difficult and time-consuming this process would have been from the beginning, I probably would have not have chosen this route.  However, having worked out all of the issues, I probably would attempt it again because it seems like there is little that could go wrong in the long run.

If I had been required to pay myself for all of my time, any of the best commercial MIDI organ keyboards would have been a clear choice, hands down!

6 Responses to MIDI Conversion of Three Pipe Organ Keyboards

  1. Yuri says:

    Could you tell me where to find the magnets/reed switches? I’m working on a 3 stack of old Schlicker keyboards. Thanks.

  2. Bob Collins says:

    Hi Stuart! Looks like you had your hands full with the MIDI conversion of those Allen keyboards.
    Very recently, I acquired 4 ivory keyboards from a vintage 1966 Reuter Pipe Organ. The keys are in excellent shape. No cracks, very little discoloration… I mean almost pristine.

    When I took them out of the console, each keyboard had a rather peculiar mechanical coupling action attachment. It was almost like a tracker, but it was electro-mechanical. They had to be removed to get to the back of the keyboards. Forgive me, but I am a novice in keyboard restoration, but I’m good in the electronics/electrical area due to my background.

    Two things are puzzling me.
    1) After I removed the electro-mechanical coupling units, the keys are now loose between the key cheeks. I would expect some play, but not the amount I’m getting.
    2) These keys have a peculiar looking spring that returns the key to the off position after releasing it.
    What puzzles me about item 1 is who do the keys now appear to be looser than they should be, since they have not moved. The only thing I did was remove the electro-mechanical coupling mechanism. The only thing I can surmise is that the “coupler” was holding the keys in position. Any thoughts? Can send a picture or two if you have any ideas.

    Then, item 2 – the springs… I see some pipe organ sites call similar items compass springs. All of the springs physically connect to the key on top. There is a small slit that the bottom of the spring slides into. The top of the spring slips under a HEAVY metal rod. I thought there might be a small track that top of the spring “grabs” to put the proper tension on the key, but no go. If the springs are positioned correctly, the key works fine; if not, the key sticks. Then it this is complicated by movement between the keys. Any thoughts?

    I have contacted Reuter Pipe Organ company with the Opus number, hoping they might share some info on the keyboards. If you have any ideas, thoughts, I would certainly appreciate your sharing them. It appears that you restore organs to usable condition. I am trying to do this myself, similar to what you did.

    Regardless, thanks for reading this, as I hope you do.

    Bob Collins

  3. Thomas Nowak says:

    Dear Stuart,
    I red your long story and and I would like add some comments. Although using reed switches is still possible like you did it is in my opinion old technology which not allow to create high quality keyboard without a lot of effort. It also doesn’t allow to convert any kind of keyboard. You have to maintain correct amount of travel and some other factors which make this method not possible to use in any case.
    Certainly the best method they are electronic switches like photo interrupters or Hall effect sensors. Especially the last ones give you opportunity to convert any kind of keyboard . Because my job is basically related to the pipe organ building I fortunately now how precise should be contact system in manuals. As well like adding touch to keyboard . This “problem was solved long time ago in one German workshop called Heuss GmbH. They developed in 80’s or even bit earlier fantastic system which based on two magnets and small lever . In such method touch is real mechanic it allow to regulate power, little null travel at the beginning and obviously weigh of keys. When I’ve seen console prepared by them to Berliner concert hall I wasn’t sure or to this console is connected normal mechanic action. All other systems cooperation between magnets and keys only are good enough to compare to electric keyboards but not so perfect like this one mentioned above. Back to contacts…. I already created Hall effect contacts they will be build in to keyboards of my friend. If you are interested with changing information about such things I’m open to write you bit more about

    • I appreciate your comments. Given the difficulties of dealing with adjusting magnets and switches, not to mention trying to control the touch with magnets, I suspect that the Hall effect switches are better. A number of people on the Hauptwerk Forum have made similar comments. I’ve not kept this portion of my web site up-to-date recently due to other priorities, but I should mention that after using the converted pipe organ keyboards for a couple of years (without any problems, fortunately) I replaced them with keyboards from MidiWorks Canada. I did this mostly because I was about to build a more finished console and the depth of the pipe organ keyboards was much greater than I wanted them to be. I think the MidiWorks keyboards are made by Fatar. I very much like the touch of the keyboards, but they do not really remind me of the one tracker organ I played many years ago. Similar to your comment on the mechanics, I would rate these keyboards as being much better than the average organ keyboards (at the least the ones I’ve experienced), but that they fall short of feeling like a real tracker action. Can you point me or other readers to more information on the contact system you’ve mentioned? I’d just like to see the details on how it functions. Thanks again for the comments.

      Subsequent note: the info is available at http://www.ottoheuss.de/en_produkte_index.htm

      • Bob Collins says:

        Hi Stuart,

        I read the information from Thomas Nowak with quite a bit of interest. I am in the midst of a converting 4 pipe organ manuals to reed switches (MIDI conversion). Any info afforded to you by Thomas or others, I am certainly interested in reading.

        The keyboards I have are somewhat rare – ivory key caps. These days they are almost impossible to find. All are in excellent shape. I think I could make their contact system work with Hauptwerk, but it is vintage 1960s. Nothing wrong with that, as these keyboards were built to last. No problem with that, but part of their return mechanism is mechanical. Stunning to see how well these worked. But I digress.

        Any info regarding alternate and better control of the keying will be greatly appreciated. I will share anything I find that may be useful to you or others.

        My background is Electrical Engineering. I’ve been pondering better ways to control the contact mechanism. Better is not always best, but in this case, any improvement could be significant.

        Bob Collins

  4. Thomas says:

    Hi Stuart,
    Thanks for your reply. I try in a few words describe my contact system. It utilise hall sensors they convert changes in magnetic field on different voltage levels. This voltage could be measured and convert on digital form. It is transmitted to main controller it controll firing point and measure speed of those changes. Thus, we have velocity control. We have to consider that velocity in organ keyboards is completely different than piano keyboard. As we know in organ important is speed of thirst 2 or max 3 mm travel of pallet. More: important is speed of closing of pallet, and also only on last 2-3mm travel. With mechanic action organ is very simple to do experiment: press very slow key and very slow depress. As I wrote any movements in second half of travel don’t have any influence on sound. As far as I know we don’t have now system which support that factor. It need much more information to record or to compute. Another story with piano like keys. Here level of sound depends on force which is function of acceleration. System has to measure speed on the start and on the end of key travel and compute acceleration from equation acc=dV/dt. More complicated but also possible in my system . What advantages? Extremely precise firing point (+- 0.04mm ) high stability, very easy regulation and changing firing point, very high durability. Finally to main controller could be connected thumb pistons and whole midi stream goes direct into computer.

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