How do combination organs work?

[johnroper100]

Companies like Walker can add digital stops to physical pipe organs. If I have an instrument that I want to add just two digital pedal stops to, how would they do this? If the organ doesn't have midi, just basic combination action, what would they have to add to the console?

[toodles]

Assuming the action is electro-pneumatic, you could add MIDI encoding to just the pedals--that would be probably a single circuit board and a power supply, plus the digital voice circuitry. . If it is a tracker action, you'd also have to make some sort of pedal contacts--much more work, and more expensive, plus the MIDI encoding, power supply, and tone generation.

And, of course, you would need amplifiers and speakers for the digital voices; if the pedal division is enclosed and there is space, you could put the speakers in the pedal chamber, so that expression control would be automatic--otherwise, it's quite a bit of work to make digital expression track the pipe expression exactly.

[jbird604]

Peterson used to make a very simple pedal extension to add a 32' octave to a pipe rank. Not sure it's still out there. But the MIDI approach is probably the most flexible and should be fairly inexpensive these days, with the proliferation of DIY boards for MIDI add-ons.

[beel m]

It looks as if Peterson still makes a 32' 00-octave unit... see link
http://www.petersonemp.com/products/pdf/LOWNOTETONE.PDF

[jbird604]

Thanks. Yes, that's the unit I've seen in several pipe organs as a 32' bottom octave. Seems a very good way to simply add another octave at the bottom to an existing 16' stop to create a 32-footer. I haven't seen it used to provide an entire new stop though. Not sure it can do that. Interesting brochure, isn't it!