[sdiy] MKS-30 filter tuning info?

[Ryan Reid]

I have the schematics, however, they do not include service notes or
tuning/calibration instructions. Oddly, I can't find them in the JX3P
service manual, either. I opened up the MKS last week, set the cutoff
to 0, resonance and keyboard tracking to 100%, and adjusted the
trimmers to play a scale in tune (by ear) after referencing C - I'm
sure this isn't the solution you're looking for, but it worked to my
liking, and the overall filter range proved OK later. Obviously you
could use a scope or tuner if you desire. Oddly, one of the other trim
pots seems to affect the cutoff as well, and I couldn't seem to
squeeze much more gain with the trimmer labeled as such.

I'll be spending a lot more time inside this thing when time comes to
me.hpf/chorus input wasn't hard to find, but the filter inputs I've
found require a ton of gain and the voice order/cycling is too strange
for me to understand as of yet. A member of Analogue Heaven pointed
out a point for global VCF audio in by way of replacing the noise
source with a switchable jack - but this apparently will also require
a pretty hot signal and I haven't tried to implement it yet. There's
also some applications for which I'd like to use the filters
individually.

Keep me posted and I'll do likewise. Good luck.

Ryan


On Wed, 9 Feb 2005 01:31:52 +0200, Samppa Tolvanen
<samppa.tolvanen at gmail.com> wrote:
> Does anyone have a service manual for MKS-30? I'd like to see what
> instructions Roland gives for filter tuning.
> 
> I also found  "a test mode" (by pressing "PARAMETER" + "3", while
> powering up), which shows what voices are playing, but can't figure
> out if it has any other use.