I was recently invited to participate in an OrganPlus concert - as you may have ascertained from that title, the premise of this concert is to present a collaborative work between the organ with another instrument or voice. There is a long tradition of piano and organ duets in the church music from the 80s-00s or so, and all piano/organ duets I've participated in have been religious, but I was really excited about this concert and wanted to do something new and unique.
I started looking around for a modern, secular duet that I could be excited about. Eventually, I found this really fun duet for two pianos by an Australian composer, David Cundy, titled Tango del Sol, but it didn't have a piano/organ arrangement. So, I decided to arrange it myself! I took the Piano II part and arranged it for the organ. The first two steps are simple:
Download Musescore here. This is the software I use for composing, transposing, and arranging.
Print and listen to a recording of the original composition. Several times. Listen for aspects such as ranges, balance, solo moments, etc. You are looking for specific elements of the original composition that MUST remain intact in the arrangement so that the quality of the piece remains the same. Highlight or mark these musical moments in the score.
Once steps 1 and 2 have been completed, go ahead and create a file in Musescore and start transcribing the original music. Musescore actually has an "import PDF file" option now! Check it out here. If the PDF file doesn't upload, you'll have to transcribe the score manually. This can take some time but start by creating an exact replica, don't worry about the arrangement part yet.
After the score has been transcribed entirely, we begin to dissect the music - chop it up into bits, and piece it back together!
Start with the baseline. This is the most obvious aspect of arranging piano music to the organ - we need to add pedals! The easiest thing to do is to put the bottom-most note of the bass clef in the pedal. Using the Tango del Sol as an example, the bass clef only consisted of individual notes, no chords. I moved the entire bass clef into the pedal.
After moving the bottom-most note to the pedal, the remaining notes and chords must be broken up between the two hands. In Tango del Sol, the bass clef was moved entirely to the pedal, leaving only chords in the treble clef. I took these triads and put the bottom two notes in the left-hand (bass clef), and the top-most note in the right-hand (treble clef).
The Solo - there was a solo moment in measures 52-64 and again in measures 78-92. I put these solo notes in the treble clef and put the chords in the bass clef and maintained the rhythmic pattern in the pedal.
This was the completion of the first draft. I took it to the organ and used a simple registration to test the piece. What I noticed was that the range of most the notes and chords was in the lower end, causing a bit of a muffled sound.
I went back to the arrangement and shifted the chords up an octave, to create a brighter, clearer sound. I also began adding notes to the chords, not just triads but filling the hands. This became my second draft and I took it back to the organ to test it.
I continued this process. Editing, testing, editing, testing, for maybe six or seven rounds. I would overcomplicate a chord and it wouldn't sit comfortably in my hands so then I would adjust it again. I would move sections up an octave here and down an octave there. There was one moment of special challenge in which I couldn't decide whether the solo continued or if there was a two-measure break between two solo phrases. When played on the piano, the solo is simply played louder than the accompaniment but in the same timbre. However, when played on the organ, a solo stop will be utilized and an entirely distinct sound will be used. So, these two measures that seem inconsequential when played on the piano were very important decisions in my arrangement. I decided that the two measures were meant to act as a break in the solo.
Executive decisions have to be made when arranging and that is why it's important to listen to recordings of the original composition and get an idea of the intent of the composer.
The last word of advice I have is just to have fun with it! Nothing is set in stone, even after I performed the Tango del Sol for the concert, I still made adjustments to the score. You can hear the organ/piano arrangement here:
Beautiful work!