It sounds like your frequency is set at the minimum all of the time, so look
at the CV input and components in that area. Most likely it IS a constuction
error.
Ken
was careful, and have thoroughly checked my wiring. Strangely when i run
audio in the Low pass i get no out put, on the band pass i get a muffled
signal, as if the cut off were set down low, and on the high pass i get the
complete unfiltered signal. Neither the cut off pot nor the res pot make any
difference except for a slight noise shift when i turn the resonance one,
but no self oscillation. I used half a tl072 instead of a tl071, but that
part seems to be working, since i can vary the gain of the signal with the
250k pot i have across the op amp feedback. I also measured the control
voltage from the freq pot which is sweeping correctly through the voltages.
I have replaced all the transistors and some of the electrolitic caps. I'm
kind of stumped, if anyone can offer any advice or points in the circuit i
can measure for known volatges that would be really very appreciated, having
spent several days on this with no results im not sure what else to try. I
am running it on +/- 12v. From what i've read this filter sounds really
interesting so I'd love to get it to work!
Ken Stone sasami@...
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
at the CV input and components in that area. Most likely it IS a constuction
error.
Ken
>Hi,trouble getting it to work. admittedly i've built it on vero board, but i
>I've built the synthacon vcf as per the rev.1. schematic, but am having
was careful, and have thoroughly checked my wiring. Strangely when i run
audio in the Low pass i get no out put, on the band pass i get a muffled
signal, as if the cut off were set down low, and on the high pass i get the
complete unfiltered signal. Neither the cut off pot nor the res pot make any
difference except for a slight noise shift when i turn the resonance one,
but no self oscillation. I used half a tl072 instead of a tl071, but that
part seems to be working, since i can vary the gain of the signal with the
250k pot i have across the op amp feedback. I also measured the control
voltage from the freq pot which is sweeping correctly through the voltages.
I have replaced all the transistors and some of the electrolitic caps. I'm
kind of stumped, if anyone can offer any advice or points in the circuit i
can measure for known volatges that would be really very appreciated, having
spent several days on this with no results im not sure what else to try. I
am running it on +/- 12v. From what i've read this filter sounds really
interesting so I'd love to get it to work!
>_______________________________________________________________________
>thanks a lot,
>Gus
>
Ken Stone sasami@...
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>