From jdm@synthcom.comWed Dec 6 12:45:56 1995 Date: Wed, 6 Dec 1995 12:37:05 -0800 (PST) From: "J.D. McEachin" To: analogue@hyperreal.com Subject: Re: Korg Mono/Poly tuning procedure.... On 6 Dec 95 at 14:46, john.. wrote: > Does anyone know the tuning procedure? I popped the top, and there's a > board with a couple of trimpots labelled (something like) hi-scale and > low-scale, so I presume that these have something to do with it. I'd also like > to get all of the oscillators lined up properly - at the moment, they all > sound slightly different! My guess is that it's similiar to the Poly6, which (I believe) has the same VCOs. I figured out how to tune a Poly6 w/o the service manual - it's just a matter of using your ears & your brain. Hopefully there's LEDs inside like on the Poly6 & Trident to tell you which voice is playing. Anyway, here's what I'd suggest: 1) Make sure you discharge all static before you open up your synth. 2) Open 'er up, staying away from where the power cord comes in to the power supply. 3) There should be a TEST switch inside that will put the synth in a test mode, which will put the synth voice in an easy to tune setting. Switch this BEFORE you turn on the synth - usually the CPU checks the state of the switch once during initialization. If there's no TEST switch, then choose a simple waveform, no resonance, max sustain, w/ the filter all the way up. 4) It sounds like you've already discovered the hi & lo-scale pots. Try playing a few keys & look at the LEDs to figure out the assignment scheme. If no LEDs, try tweaking one of the lo-scale pots until you hit upon the right voice. If possible, put the synth in UNISON mode and turn down the volume of 3 of the VCOs. 5) Now you need a good tuning reference; digital synths are usually good for this, but make sure that it's tuned to A=440Hz. I went over the a friend's once and everything was sounding screwed up. He said "I can't get ANY of my analogue in tune". I discovered that his M3R was set to A=442, w/ a Just Temperament! 6) Try pressing low C and tweak the hi-scale pot for that voice. Then, play high C and tweak the lo-scale pot. Repeat until they're both in tune. What threw me about the Poly6 was that I tuned the low keys w/ the hi-scale pot and the high keys w/ the low-scale pot. It seems bass-ackwards to me. Maybe they fixed this on the Mono/Poly, but I doubt it, as I believe they were engineered at the same time. While you're at it, you may as well crank up the resonance - look for the RES pot. That 2044 will howl! You should also check the filter tracking - turn up the resonance. Hopefully there's a test mode to set the filter tracking to 1 and the envelope mod to the right spot - that's the trickiest part about tuning a filter, which you may have to play with. Anyway, adjust the "fc" pot until it tracks. That's it - should take less than 30 minutes. BTW, I've typed out a long TRIDENT tuning procedure if anyone needs it. JDM Synthcom Systems