I own both a micromoog and a multimoog, theres one differnce I can notice. The micromoog’s filter seems to be more responsive, warmer and just plain more organic. The multimoog seems less of all the above. Now I know both synths use the same filter, ive opened up my multimoog and noticed the main board actually says “micromoog” on it. But by adding the 2nd VCO did it cause something to make the filter act different, or could it have just been a change in the later era micro filter? Maybe my filter isnt set right? Is there anything anyone could attest to why it may be different? Kevin? MC?
I think it’s just the higher drive level of the micro’s filter.
This results in higher harmonic distortion.
Had they done the same on the multi, it would have resulted in higher intermodulation distortion, which is not as pleasant sounding.
I’m afraid I can’t explain it, but I can certainly back you up on the observation. Although, it seemed like more than just the filter to me. Something about the two oscillators being mixed together the way they are— just seems to soften and thin out the sound alot. It doesn’t end up with the same robustness that the Micro has.
I’m always amazed at how good your ears are!
Maybe this will help…
The way the Multimoog mixes the two vcos together, the average output remains fairly constant.
So unlike traditional mixing where the volume can become greater the more inputs are added, the Multimoog stays level whether the osc mix is panned to A,B or in between.
Adding suboctaves throws this averaging off a bit, fwiw.
Contrast this above with a Minimoog.
On a Mini, one mixes in 1, 2 or 3 vcos.
The filter drive is up to the player.
Moog lowered the maximum audio filter drive as minis got higher serials.
Earlier ones could get more intermodulation distortion.
Also, the later temperature compensated vco boards had hot outputs.
Put a later vco board in a really early mini and enjoy lots of distortion. 
(actually don’t do this- early mini power supplies won’t like it much.)
Why, thank you. I spend a significant amount of time with my synths and I like to think that I know them pretty well. So, I’m always pleased to hear a technical explination for various phenomena I experience on a more aural and intuitive level.
This is precisely what it sounds like. The cross-faded VCOs ruin this synth for me. It’s such a cool synth in many other areas, but the fundemental tone from the VCOs is always muted and tame.
Exactly. It’s unfortunate in some ways that it always comes back to the Mini; But it is simply, and IMO undisputably, the standard from which all others are judged. It’s just the best, tonally speaking.
Do you know the serial cut-off for this lowered filter drive?
My Mini is a 199X., does it make the cut?
Thanks again Kevin… I’d been wondering about this Multi VCO thing for awhile…
Do you know the serial cut-off for this lowered filter drive?
My Mini is a 199X., does it make the cut?
Good question.
The service manual says “Serial numbers below 2000” can have more intermodulation distortion and suggests some resistor mods.
But I don’t like the sound as much after the mods.
Later Minis (sorry, I don’t have the serials) changed these resistors even more so in the quiet direction.
One of the later mods also involves lowering the volume of the A-440 tone.
I don’t recommend this one either. The A-440 is just too quiet after the mod, in my opinion.
There’s all sorts of changes made through the years to Minis though.
I’ve got a bunch documented, but not usually with serials.
I’ve only seen about 400 odd minis so it’s not easy to know the exact serial where a change took place.
I didn’t start documenting them until about 4 or 5 years ago either.
I recieved a ton of original service documents with my Mini, including many field service bulletins. if you think I may have some that you don’t already own, or aren’t familiar with, it would be my pleasure to share them with you.