Putting an effects insert into a leslie organ

[klysandral]

Hey everybody, just registered to this site, so much cool stuff on here! I am just getting started in DIY audio projects, but there's a couple I'd like to get some advice on. The first is a project modifying an old electric organ I have with a leslie speaker. I would like to put an effect insert into it to modify the signal coming from the various oscillators BEFORE reaching the leslie. My main question is where to insert it into the internal signal chain of the organ, should I put it before the amplifier or between the amps and the speaker?   

[expanoncolin]

Welcome!

Before the amplifier.

-Colin

[klysandral]

Hey thanks for the quick answer! I suppose this makes sense, I should have just pictured it like a guitar set-up, running pedals on the front end is basically Oscillator > effects > amp > speaker yes? Before I do this are there any other glaring dangers I should be aware of?

[expanoncolin]

Before I do this are there any other glaring dangers I should be aware of?

Well, there will be some line voltages running around (those connected to the wall), which could kill you - so be very careful!

-Colin

[crochambeau]

Most organs I've interacted with have multipin connectors between sections. These multipin connectors will OFTEN carry the various low voltage supplies from the PSU, etc. I have also seen these multibuss lines carry AC mains from the wall.

Be aware, older organs are very complex devices and without a service manual you'll need to be able to identify hazardous elements.

That said, I would look for a REVERB or TAPE send/return, as those were both common elements in later units. Tape will deal primarily with line level, reverb send is probably going to be at a level similar to a headphones send, so a touch hot but still within reason more or less.

You may luck out and find RCA connector feeds for all your audio needs, but, just be careful - you can find AC in surprising places.

[klysandral]

So I opened up the back of the organ to take a look and found two promising things. One is that there is a spring reverb in the organ and the other is that there is a phono input that is from what I can tell a TS input just before the amplifier. The phono input does not run into the leslie speaker however, only the stationary one. My main question though, is if I take the wires on either side of the spring reverb, could I solder in some 1/4" input/output jacks on the end of them and basically have an effects send/return or would I have to alter the signal passing through there in some other way first? 

[expanoncolin]

Probably not - the signal going to the spring reverb is meant to drive the reverb tank's transducers, not to be sent to effects pedals.

-Colin