Digitising a 3 Manual Compton-Makin Organ: Part 5 - Audio and software

Laurie Kirkcaldy

• 2 min read

Final bits is connecting up the MIDI control to something that can actually output Organ sounds. For this I used a ThinkCentre mounted under the front using a healthy amount of 3M velcro:

This then connects via USB to the MIOS32 MidiBox, and USB, originally to a MOTU 828mkIII sound card, but then later replaced with a Behringer. The reason for the "downgrade" was that the MOTU, in classic MOTU fashion, had driver issues in windows and no matter what I did would always end up dropping out about 30-40 minutes after booting. The Behringer on the other hand seems fine...

GrandOrgue is used to play back the actual organ pipe samples and add reverb as a free and Open-Source alternative to the very expensive Hauptwerk. There are a number of free organs available, from small 2 manual things to large composite organs which I use in mine.

The audio travels out as 8 channels from the behringer into a SoundWeb Green DSP, used for some mixing between speaker channels and EQ and Sub-crossover (probably a bit overkill, but I do sound and other tech freelance, so it's sort of my thing! At least I didn't put in a Symetrix Edge/Radius). I use the original amplifiers in the base of the organ, not least because when I took them out, the organ became rather front-heavy and started tipping... They also work fine and are quite a useful 6 channel amplifier with integrated power control to the main organ controls.

Things I'd still like to do on this organ:

  • Add the transpose knob to.. transpose in GrandOrgue. Currently this knob and control is rather stuck in place, and I can't get enough space to solder new wires on
  • Mount volume knob - currently it's just a potentiometer connected to the soundweb green dangling out the front. It'd be nice to have it mounted properly and make it look like it's meant to belong
  • Replace the keyboard scanners - They sometimes crash / miss note offs and doesn't always start up properly on power on.
  • Stop control, specifically the software pulses, seem to sometimes miss the off part and will get stuck on with both forward and back solenoids for a stop stuck on. Probably my bad code that I wrote 3 years ago
  • Replace the expression pedals to use potentiometers - as funky as the original mechanism is (see earlier pages), they are not reliable and don't work particularly well