ASM-1 up and running

gstopp at fibermux.com gstopp at fibermux.com
Fri Oct 4 18:38:49 CEST 1996


     Regarding the LFO low end problems - three things come to mind:
     
     1. Sucky capacitor - try using a poly-anything. Optimum value is 1uF.
     
     2. The op-amp has an offset problem. Swap it out for another, go
        through your stock until you find the best one. Are you using a
        real TL-082? If you are, then go to (3).
     
     3. Excess solder flux. This is one of the sneakiest evils you can fall
        victim to. Use Flux Remover, not alcohol. I know, special stuff,
        expensive cans, but it's worth it, especially in charge/discharge
        circuits.
     
     Good luck!
     
     - Gene


______________________________ Reply Separator _________________________________
Subject: ASM-1 up and running
Author:  yrrab at well.com (Barry Bernard) at ccrelayout
Date:    10/3/96 11:10 PM
     
  Just thought I'd mention, I have my ASM-1 project up and running. I built it
with the maximum amount of pots and jacks. Almost everything worked 
perfectly right off the bat. It sounds great ! I'm still ironing
out a few problems here and there. One thing I recommend is soldering in the 
"optional" 30pf capacitor across the feedback resistor of the VCA, otherwise
you will get high freq oscillation on the output of the VCA's, only at a certain
control voltage input level. This can be heard as "clicking" when you modulate 
the VCA every time you pass that certain voltage. Adding the capacitor gets rid 
of the problem.
   One thing that has me stumped is that the with really low frequencies
(like less than 1 hz), the output of the LFO seems to be asymetrical. On 
the triangle wave, the rising part takes a lot longer than the falling 
part. On the square wave, the voltage stays low for much longer than it 
stays high. I believe I just used a ceramic dip capacitor, could this be 
the problem ? Apparently it's discharging faster than it's charging at low 
frequencies. Also, although my LFO goes well up into the audio range, it 
stops oscillating when it gets below around .2 hz. Of course I'd like the 
LFO to do really slow sweeps. As far as I know I put the proper components 
in.
  Anyone have any suggestions ?
     




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