ASM-1 Notes

Dave Fulton dfulton at
Sun Mar 23 20:10:45 CET 1997

A couple of things I have learned about "my" ASM after assembly.
(In otherwords I hope these are normal for most ASM kits)

1) Use Huge caps, 2200ufd worked best with my bench supply. All problems I
had with the LFO & the ADSR crosstalking into other modules were
eliminated when I installed these. 

2) Speaking of caps, Use the cheap .1ufd caps for bypass apps, I 
have tried both and there was little or no measurable change in the noise on 
the rails.

3) I can only achieve about a min of .08 voltage swing on the lowpass 
output when adjusting the offset controls of the filter. Is this the normal?

4) Is a small mount of pumping noise normal with this type of filter?
It's not as clean as my Serge filter but it does sound nice. (SEM like)

5) Install 30pfd caps in the feedback loop of the VCA's, mine tended 
to osc. with no connection to the the CV in's.

6) The .01 cap that Christopher List suggest you use as a point to drive 
your Gate LED has about 11v on it at gate on time. (This is with a 12v 
supply). I am using red 2 ma LEDS with 10K current limiting resisters and 
am drawing about .85 ma with plenty of LED brightness.

7) A 12 volt supply appears to work just fine, nice because I can use my 
serge power supply to drive all panels.

8) The ADSR's can be set up to emululate serge envelopes (well kind of) I 
have set mine up so I get a 6V Attack peak and 6 volt sustain voltage, 
I then scale the output to 5 volts. (The same as my DSG >my only point of 
reference< )

There will be more Later.

Dave Fulton
Oregon Public Broadcasting 
Engineering Dept.

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