Building a Hauptwerk Organ

Here’s the “before” picture of Alf, a Rodgers Columbian 75 organ from 1972.

Having a digital organ in my living room has been a dream for many years, but they can be quite costly (for comparison, the cheapest Allen starts around $14,000!). A friend has one in his living room, so we started talking about making it happen for me! After a few weeks of searching, we found a free Rodgers Columbian 75 on Facebook Marketplace.

It was purchased by a Bound Brook pastor in 1972 and, after a few moves, ended up in King of Prussia PA. He passed away in 2014, and it was time for his wife to downsize. The organ was in great condition, and it was free – I just had to pay to move it.

The pastor who owned the Columbian served a congregation in Bound Brook (twenty minutes from where I live). He had taught classes at Drew University (where I did my second Master’s degree). These and so many other coincidences were proof that this was the organ for me!

So welcome to this page, a place for (ir)regular updates to the transfiguration of the Rev. Dr. Alf O. Olsen Memorial Organ – or as I like to call the instrument, Alf!

Day 1

It’s pick-up day! I arrived in King of Prussia bright and early, met a few of the organ owner’s surviving relatives, loaded it up in a truck and headed back to Somerset. The organ arrived at home shortly after noon and took its place in the living room. I did some preliminary digging around, tested some circuits with a multimeter, and let Alf get some sleep after a long day. I also made some plans for the arbitrary stuff. The plaques (Rodgers, divisions, transposer) have been measured. The stop tabs probably won’t be used and the Rodgers “practice panel” might be the mounting area for a Novation Launchpad Mini (for all the stop controls) or a small touch-screen monitor. I may also replace the power switch’s indicator light with a momentary rocker switch, allowing the organist to toggle between multiple organ sample sets.

Day 2

Today was a big day for Alf. I got a great deal on a refurbished MacMini, my Hauptwerk license was authorized, I installed a second sample set (the Grand Organ of Our Lady of Mount Carmel in Chicago), and Alf’s circuitry got some more poking and prodding. I started a rough list of the things the organ will need:

  • the Pratt-Read keyboards need several new bushings, but I probably won’t replace all of them
  • several of the pedalboard reed switches need to be replaced, and they’ve been ordered
  • the transposer pistons are in good order, so I’ll use those as general pistons

Day 5

My schematic drawing
This is how a creative-type draws a schematic!

It’s almost time to start the cutting and gutting! Before I cut a single wire, I’m spending a lot of time reviewing the original Rodgers schematics, as well as drawing my own. I also need to be certain that anything I don’t intend to use is completely disconnected from the power supply. No electrical mishaps here, please!

The parallel MIDI scanner boards (for the keyboards) have been ordered from Classic MIDI Works, along with a new prewired harness with 32 reed switches for the pedalboard (which includes a matrix scanner board). This will save me having to replace all of the old reed switches – instead, I’ll use the reed switch mounts and pedalboard magnets already present.

The remaining matrix inputs will be used for the (former) Transposer pistons.

In the next few days, some major changes should be visible. Stay tuned!

Day 6

Almost everything has been removed.

Last night I began the gut job, so between yesterday and today a LOT has happened. The power supply, amp, woofers and tweeters, tremolo motor and cone, reverb unit, and all but one of the old circuit boards have been removed. It’s pretty empty in there!

The remaining wire harnesses.

In terms of circuits and wiring, all that remains are the Swell wiring harness (yellow), Great wiring harness (red), potentiometer wires (not visible), piston wiring harness (green), and the stop tab wiring harness (orange). I plan to use the keyboards and pistons, so those are kept neat and laced. They’re also still connected to the last circuit board, since they’re soldered in order. This will save work connecting the scanner boards. At the moment I don’t have plans for the stop tabs – so while I’ve left the wiring in place, they are zip-tied out of the way.

It’s been less than a week and Alf is already in great shape. In fact, once the scanner boards arrive from Canada, the organ conversion will be done in no time! All of the Hauptwerk programming which can be done without the keyboards and pistons is done, and almost everything else is ready to go. However, I’ve come across two potential problems.

Problem one. I had originally planned to parallel wire the pedalboard, since I thought there were only a couple broken reed switches. Once I noticed several had either failed or broken, I opted for the prewired harness which comes with a matrix board (as mentioned above). This isn’t a really problem, and it’ll make the pedalboard wiring much quicker; however, now I need to find a way to matrix wire the pistons (although they are currently parallel wired).

Problem two. After removing all the electronics and speakers from the console, I’ve noticed the organ seems top-heavy. There was quite a bit of weight mounted to the floor of the console, and now most of the weight is in the keyboards (and the scanner boards are light, so they won’t help). Although this will make moving the console much easier, I may get a couple bricks or sandbags to keep within the cabinet to make sure there’s no risk of tipping.

Day 18

The new Control Panel to load the next sample set and shutdown the computer.

Very little has changed in the last several days. I’m still waiting on the MIDI scanner boards to ship (although they’re expected to leave Canada this week!), and so there’s little to do.

I remembered that the console has a heavy back panel which, once replaced, should help with my concerns about the console being top-heavy. I also drew up some schematics for matrix-wiring the pistons (which I’ll talk more about below), so my two problems from last week seem to be addressed.

The console is in good shape to plug-and-play – which means I’ve just been doing some minor aesthetic work.

The new General Pistons are installed.

With the former Practice Panel, I printed, laminated, and mounted a new panel with some important Hauptwerk controls. The “Next Organ” button is a momentary switch which will increase the cued favorite sample set and then load it – meaning the organist will be able to change organs at the push of a button. The “Shut Down” switch will run a Hauptwerk command to shutdown the MacMini – meaning the console won’t need a mouse.

For the former Transposer controls, I printed, laminated, 14mm-punched, and mounted new covers for each of the pistons. The quality on these isn’t great, and the font could more authentically say “organ,” but they will function quite well. Also, because they’re just laminated card stock, I can easily replace them in the future.

That’s all for now – but once those scanner boards arrive, we’ll be playing in no time!