From mdma@primenet.com Tue May 28 10:31:03 1996 28 May 96 13:29:57 +0500 28 May 96 02:16:33 +0500 Date: Mon, 27 May 1996 23:12:50 -0700 (MST) From: Jam Master A Subject: Moog Opus-3 VCF/VCA Input Mod! In my quest to take a soldering iron to analogue synth I encounter, I tonight added an external-audio input to a Moog Opus-3 synth. Here's what you'll need some wire soldering iron and solder, + electrical tape a capacitor and a resistor (I used a .47uf cap and a 100k resistor) (then again, I was just guessing and trying didderent values until it sounded good.) a scredriver paper towels (ill explain later) I used the HOLD jack on the back for the filter input jack - my friend never uses it anyway! Remopve the screws that hold the top of the unit on. You will see a circuit board next to the keyboard, and one screwed in to the top where the sliders are. we need to get to this one. remove all the screws that hold the top board in place, and take off all the knobs from the front of the unit. take off the slider caps while you're at it and store them safely with the screws. There will be a bunch of black gunk covering the board that once protected it from dust. in a previous life this gunk was foam. remove it all carefully. Look on the top of the board, for transistor Q-12. Theres an IC next to it. (IE: A CHIP@!#$) Look fo the left side of the chip, (looking at the top of the board) for the 2nd pin from the top. Solder a wire to this pin on the back of your board. On the other siden attach the capacitor and the reesistor in series. I merely tried a bunco of components i had around until i found a good match, so you can safely try or use other values (OK i got the parts out of a broken telephone! so sue me! all you have to do now is wire up the ground on your jack to the common ground (the sleeve) on the other jacks and... you're in business! We were running a tr-606 (always a popular candidate to filter) and it sounds great. Well, it sounds like a 303 through a Moog filter! 1) you need to hit a key to get the audio signal through it. i usually tape one down for the duration. If you get brass or strings with your input sounds play around - i wrote this from memory and we had to fiddle a bit to separate it.i think my solution involved panning the sounds, etc i forget. Anyhow, enjoy!!! peace out - adam mdma@primenet.com