Organ split

[Firepowerforfreedom]

Seems like I'm perpetually researching rather than actually trying anything with my organ (I blame my college homework), but I had a thought about performing a simple organ split.

The main problem with splitting the keyboards from the tube channels is the mass of parallel wires that connects them. Is there a simple way to create, say, a serial connector that would be able to quickly connect and disconnect the keyboards and the tube channels?

[trobbins]

I would think you have to go digital, ie. muxed sensing of keyboard switchs, and muxed output of switch contacts (possibly open-collector or drain switchs, or possibly optomos), and a serial coms between, with at most a few ms transfer delay - great simple digital electronics project for academic courses.

[stratus46]

Originally Posted by Firepowerforfreedom

Seems like I'm perpetually researching rather than actually trying anything with my organ (I blame my college homework), but I had a thought about performing a simple organ split.

The main problem with splitting the keyboards from the tube channels is the mass of parallel wires that connects them. Is there a simple way to create, say, a serial connector that would be able to quickly connect and disconnect the keyboards and the tube channels?

MIDI. Serial digital control sends back note and if the keyboard is equipped, velocity of the key press. The keyboard end is comparatively easy. Decoding MIDI to drive the tubes would be more 'interesting' but certainly not impossible. Once you've converted the tube section to receive MIDI a whole host of possibilities appear.

G²

[Knarf]

What type of tube organ are we talking about? If your organ is similar to the tube organs I have seen, then the keyboard switches carries complex analog signals and form integral parts of the tone controls, filters and delay lines.

If this is the case in your organ, then the switch connections cannot be replaced by simple serial on/off circuitry, digital, MIDI or otherwise. Any attempt at doing so would just ruin the whole thing. May as well build a completely new semiconductor based organ while reusing the old chassis.

- Frank.

[trobbins]

He may be lucky Knarf and have a relatively simple older style organ, as my organ switches three note busses to ground with every key, and has three output busses and 12x5 note inputs, and so the two keyboards could be replaced quite acceptably with an optomos matrix sitting between the note generators and tone filters, plus another set for the pedals of simpler format. Each of the three key switchs are between 10M and 2.7M buffer resistors, so any optomos resistance would be fine.

In some ways this would be a reliability bonus for my unit.

Ciao, Tim

[Firepowerforfreedom]

OK, I'm not sure if I explained clearly, but thanks for the suggestions already. I'll rig up a YouTube video to show what I'm thinking.

Btw, it's a 1962 Conn 427M Caprice home spinet.

[Firepowerforfreedom]

OK, here's the video: YouTube - Organ split question

Excuse my non-technical language—I'm a newb, but learning quickly. So, what do you think?

[stratus46]

Originally Posted by Firepowerforfreedom

OK, here's the video: YouTube - Organ split question

Excuse my non-technical language—I'm a newb, but learning quickly. So, what do you think?

IIRC Conns used multiple contacts per key, 8' 4' 2' pitch, possibly 16' and 2 2/3' depending on the model. The oscillators are running continuously and you select the pitch(es) with the keys. Remoting it digitally will be hard. Analog will be even more difficult with the large number of wires and potential cross-talk. And when you're all done, it's still a Conn.

Just for laughs check out Hauptwerk and the examples played on YouTube to see what is possible with computers and MIDI. I predict you'll be impressed and maybe want to abandon the Conn project.

G²

[Firepowerforfreedom]

Originally Posted by stratus46

IIRC Conns used multiple contacts per key, 8' 4' 2' pitch, possibly 16' and 2 2/3' depending on the model. The oscillators are running continuously and you select the pitch(es) with the keys. Remoting it digitally will be hard. Analog will be even more difficult with the large number of wires and potential cross-talk. And when you're all done, it's still a Conn.

Just for laughs check out Hauptwerk and the examples played on YouTube to see what is possible with computers and MIDI. I predict you'll be impressed and maybe want to abandon the Conn project.

G²

OK,
I'm not trying to change the sound. I'm trying to physically split the organ into two sections to make it easier to transport. What I want is to make disassembling it and reassembling it as convenient (or painless) as possible.

The sound is going to stay the same, the organ is still going to do what it's supposed to. I just want to know if cutting those wires, creating connectors for them, and reattaching them will screw up the circuits at all.

[trobbins]

I think you will find that you can easily cut and place connectors, or even extension leads, in the key/switch cableforms shown in your video. I reckon your keying set up is very close to my Selmer setup - the tone generators get keyed through to later tone shaping circuits, such that the signals being switched by the key contacts are just the oscillator outputs. Of course signal bleed will progressively increase with longer extensions, but I doubt you will notice any difference with short practical lengths.

You may want to consider using generic connectors and pre-made cables, such as used for computor serial or parallel connections. Enjoy the soldering!

Ciao, Tim