Hooking up an Omnichord OM84 and a Korg Monotron Delay

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Hi,

My first post on this excellent forum!

I want to cut into my Omnichord OM84, just before the main amplifier (see image), route the output into a Korg Monotron Delay and the output of the Korg back into the OM84 to the main amp.

Problem is that the Korg has a line-in and line-out; the levels of the OM84 are (at least to me) undefined.

I'm not sure if I need to do something about the difference(?) in levels, take impedance into account, or ...?

If somebody could help me out I would be very happy.

Attached the schematics of the OM84 and the Korg Delay.
 

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long cables here could cause hum. I would run a twisted pair out from the point you picked, through the delay and out of that to a powered speaker. After all a TDA7222 IC amp is about a $5 part, the transformer about $20. Unless you use a 19 vdc computer power supply, $10.
That would be 1/2 the length of line level cable. Shielded twisted pair is even better but you have to us TRS connectors with shaft to shield one end.
You could cut the point you have the arrow to with a switched TRS or phone plug but that is risky. Those switches oxidize over in the long run and block the signal, they are just tin plated. I think the impedance should not be a problem, as long as the delay is standard 2 v in out (or 1.6 v)
 
Hi Indianajo,

Cable length is (hopefully) no problem since I'm embedding the Korg in the OM84 and use its own amp and speaker. My interest is more if I need any kind of buffer circuitry for either signal level, impedance etc.

Thanks!
 
You could pad down the omnichord output with another pot to make sure the input doesn't go higher than 2 vac. Once you find out what values to use you could use fixed resistors. You'll need an analog vom with 20 vac scale or a scope to see the level going out to the delay unit.
That is a 50 k pot, one end input one ground, wiper to delay unit. I think any transistor should be able to drive two 50 k pots instead of 1. If you lose low frequencies you could replace the 1 uf coupling capacitor with a 2 uf.
 
I would start with the most obvious hack. Just try it.

The signal into the power-amp chip is very small, like 0.025V. I suspect the Monotron expects higher levels in/out. Maybe you can balance it out with gain knobs.
 

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