Oscillator organ to synthesizer—mission impossible?

uh, no, not really. You don't list a brand. Most brands of organ before 1980 were chock full of electrolytic capacitors that are all dried up now, so they all need replacement just to make it an organ again. They generated triangle waves typically, then filtered them down to organ sounds. After 1980 cheap organs were full of LSI organ chips that might work now but are irreplaceable if they don't. The exception is Hammond, but you know what Hammonds are worth.I believe (I never owned one) Moog synths had triangle wave, sine wave and envelope generators (VCA), and a patch board. Hammonds were basically additive analog sine wave synths with a tonebar mixer control instead of a patchboard, and Hammonds mixed with transformers, not resistive dividers & amps ("mixers"). The H100 Hammond model, often selling for $100 these days, has the patchboard in the back in addition to the tonebars in front. It also has a rudimentary envelope generator (percussion). I'm having a ball planning modifications to mine- getting rid of the unreliable tube sockets (bad connections) and putting in solid state stuff with additional percussion curves (envelopes) etc. There is tons of space in this old thing for SS tricks, including plenty of contacts for MIDI.
 
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Organs...

Most, if the they have a top octave oscillator per note... a total of twelve with digital dividers for the each lower octave, use diode gating. The keyboard turns on the correct note using the diode gate and it is routed to filters to form the voice. The newer ones are microprocessor controlled, digital again but the voice is usually digital samples. A diode gated organ can't easily be converted to analog, I think.
 
It's a Conn 427M caprice. Not sure if it uses one oscillator per top octave note. I'll check later and let you know. Conversion to solid state is also on my list of ideas.

I'm not so much interested in converting the whole organ to analog, only a single manual. My plan would be to take what I have on hand (plus a little extra) and reduce it into a small analog synth.
 
Looked at your picture. Tube city. The good news is that this thing is so old, there is probably only the one electrolytic cap, the can on the power supply. Those are available from FP at tubesandmore.com or triodeelectronics.com. Maybe one on the upper right, look to see if that yellow thing has a plus on one end or minus on the other.
The bad news, is that these were not very stable in pitch, and needed tuning frequently.
Sines and triangles gives you basic opportunities in the synth area, but there is not a lot of room for S.S. toys. I would either replace the electrolytic and keep it with the back plexi-glassed over for comedy relief- or convert it to Midi by connecting the keyboard to Midi scanners and hooking them to a PC. I had a computer that had more tubes than this, about 1966. It was dumber than a $.99 calculator. But it was an awesome collection of fifties hardware, with a bad magnetic drum drive not compatible with floppies. I'm confining my tube mania to a ST70 amp, a PAS2 preamp (nothing visible, ****) and maybe a bogen 10W amp to convert to higher-fi.
Have you seen Arcade Fire's (band) round projection B&W "TV" with artificial snow? Retro is in, if you are trying to be really different. They also have a pipe organ on stage. You could intercept the keys on the way to the oscillators for midi relays, dress up in a white lab coat & Einstein hair, and play Adam Ant covers in bars with this thing.
 
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Here's a pic of under the swell manual. Are those yellow tubes also electrolytic capacitors? Austin Leeds's Photos | Facebook

I had thought about the midi route, but I cant find anything cheaper than $500. If you know of a place that could give me a whole kit for less than half a grand, I'd really appreciate it.

I like the look and feel of this organ, I just hate that it requires multiple people to move. My goal with this thing would be to get it small enough to take places for performances. What would be my best option for this?
 
Well, I see you are already on organforum.org. Unfortunately kikennon's thread on ultra cheap midi implementation has disappeared. He was giving away software to scan $29 scanner boards. He had a website, kikennon.com, which I haven't checked lately. Midi-boutique is for rich people. Wait til after the holiday, I'll tickle the moderator at organforum to make kikennon's post show again. The PC source is up to you, but the soltware, jorgan, is free. You can also buy old sampler synths like the Ensoniq EPS for about $100, if you can get the keys to midi format.
As far as moving the organ, a 4 wheel 1200 lb dolly from mcmaster.com makes anything under 400 lb a snap if you don't have to go up stairs. The guy that helps me move pianos has a hernia and doesn't do much but balance the piano to not fall over, and stack up boards under the end I just lifted until I get it on or off the dolly. We used 11' ramps from U-haul-Ryder trucks to get out of houses and into the truck, and vice versa. Into my house which is 7 steps up we would strap the organ up (400 lb) to a port-a-pull and winch it up the ramp into the house.
 
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The old Conn I had long ago had a single oscillator per pitch with multiple contacts per key turning on 16', 8', 4', 2 2/3' and 2' pitches. The oscillators run continuously and are not locked to anything. Each of those 'transformers' are actually inductors with a spring loaded 'I' piece next to the 'E' core. Adjusting the nut at the spring changes the inductance and tunes the oscillator. A truly dreadful musical appliance. It's already analog so 'converting' it would be replacing the oscillator array with a new tone generator system. Not inpossible but not trivial. Yours looks very much like mine including the gas regulator for a 75V supply. I replaced that with an amplified Zener diode.

Look into the Hauptwerk system by Milan Digital audio. That will be an instrument, not an appliance (as most electronic 'organs' are).

Hauptwerk Virtual Pipe Organ

 
Forgot to mention, I wrote keyboard scanning software (assembly) for a pipe organ I built in '89. It runs on an MCS-51 family processor but is easily converted to 68HC908 family. My software was for a dual contact X-Y array to get MIDI velocity on a 5 octave keyboard (I made some changes to use on an 88 note piano keyboard) but could be easily changed to use single contact with fixed velocity. Free to a home if interested.

 
. Are those yellow tubes also electrolytic capacitors?

I had thought about the midi route, but I cant find anything cheaper than $500.
If your yellow tubes don't have a plus on one end or minus on the other, they are not electrolytic. Also, if the value is less than 1 mf they are more likely paper dielectric. Paper dielectric deteriorates some over the years, but if nicely sealed up with wax (as the high quality ones were) they hold up way better than electrolytic. Paper caps don't explode, either, as electrolytics can in the power supply near the power amp.
I found Mr Kikennon's thread on his giveaway scanning software for a cheap commercial key scanning PCB, MIDI Programs Posted I'm thinking of buying some of these for my H to add midi controlled sounds. Hauptwerk as mentioned above, is, I believe, even more expensive than midi-boutique, and runs on a fairly capable PC. The diy'ers in organforum are running more to jorgan for PC's which see.
I've got some Intel 8051 PCB's from the early 80's, but they are not the intel brand MCS-51 board, so I doubt Stratus46's software would help me. Thanks anyway. Not much chance of finding a PROM programmer for those obsolete PROM's, either. Mr. Kikennon's stuff runs on allegedly currently available technology. Several people on organforum warn against implementing matrix keying, as opposed to 1 at a time, and the Conn is definitely a 1 at a time box as now wired. Again, much thanks for the offer.
Lot more knowledge is available on organ forum, firepowerforfreedom, so if you get into this start a thread on the midi section over there. Sorry I didn't see your posts. Midi-boutique is a painless solution, but way above my budget now, and perhaps, yours.
 
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If your yellow tubes don't have a plus on one end or minus on the other, they are not electrolytic. Also, if the value is less than 1 mf they are more likely paper dielectric. Paper dielectric deteriorates some over the years, but if nicely sealed up with wax (as the high quality ones were) they hold up way better than electrolytic. Paper caps don't explode, either, as electrolytics can in the power supply near the power amp.
I found Mr Kikennon's thread on his giveaway scanning software for a cheap commercial key scanning PCB, MIDI Programs Posted I'm thinking of buying some of these for my H to add midi controlled sounds. Hauptwerk as mentioned above, is, I believe, even more expensive than midi-boutique, and runs on a fairly capable PC. The diy'ers in organforum are running more to jorgan for PC's which see.
I've got some Intel 8051 PCB's from the early 80's, but they are not the intel brand MCS-51 board, so I doubt Stratus46's software would help me. Thanks anyway. Not much chance of finding a PROM programmer for those obsolete PROM's, either. Mr. Kikennon's stuff runs on allegedly currently available technology. Several people on organforum warn against implementing matrix keying, as opposed to 1 at a time, and the Conn is definitely a 1 at a time box as now wired. Again, much thanks for the offer.
Lot more knowledge is available on organ forum, firepowerforfreedom, so if you get into this start a thread on the midi section over there. Sorry I didn't see your posts. Midi-boutique is a painless solution, but way above my budget now, and perhaps, yours.

That's perfect—I'm definitely going to miditize this thing now, barring any accidents or excessive hidden costs. I think I'll slice off the bottom box and just use the top console, then get it a stand. Thanks for your advice and help, guys!