MOTM

I've written a procedure for modifying and tweaking MOTM oscillators 
to improve tracking at the higher frequencies.  The procedure is 
based on my own experimentation with both the 300 and 310 series.  
I've been able to achieve tracking accuracy better than .3% across 7 
octaves.  The procedure is rather complex and too long to post here. 
Larry Hendry has been kind enough to post it on his site.

http://www.wiseguysynth.com/larry/mods.htm

I hope to have my own site operating soon with all sorts of MOTM 
mods and tips.  As well as information about my studio (shameless 
plug)

Paul Haneberg

Paul H,

I can't imagine swapping HF resistors until you are satisfied - 
that's masochistic! What happens if your supply voltages ever change 
slightly?

I have one (out of six) 300s that doesn't track quite as well in the 
upper registers. I've thought about installing a cermet trimmer for 
HF compensation, just like some of the better older designs.

Moe

> From: "paulhaneberg" <phaneber@...>
> 
> I've written a procedure for modifying and tweaking MOTM oscillators
> to improve tracking at the higher frequencies.  The procedure is
> based on my own experimentation with both the 300 and 310 series.
> I've been able to achieve tracking accuracy better than .3% across 7
> octaves.  The procedure is rather complex and too long to post here.
> Larry Hendry has been kind enough to post it on his site.

The timing of this post couldn't have been better. I just got my second 310
assembled and calibrated (making 1 300 and 2 310's in the system). Noticed
some beating and went to re-calibrate my 300, and realized that the tuning
curve over 5 octaves was wacky, to say the least: it would calibrate fine
for the first 3-1/2 octaves, then the tuning would very quickly go flat in
the top 1-1/2.

Turns out I, too, have a 470pF instead of 4700pF in mine, which I didn't
even realize until now. I'm also seeing a crazy pitch change when I change
the position either of the FM2 switches. This seems strange, but what do I
know?

Fellow perfect-pitch-cursed musician,
Eric