Irrelivant foreword in italicised text: I am often reluctant to tell people about my projects untill they are done, otherwise I feel like I'm letting them down when it doesn't work or I don't finish it because I'm distracted by another project, but in this case I've decided "**** it" and I'm going to tell you that I'm working on a synthesizer (mostly analog) because I am confounded and have a deadline.
I've been looking up circuits and chips for a voltage controlled filter, found a great chip: the lm13700, a transconductance op-amp, looks like it will do the job just fine but if you have any suggestions please make them
However, when researching circuits used by synthesizers, they allways seem to have multiple stages in the filter; all the same and all controled by the same control voltage.
Exhibit A: The Roland SH1 filter (see page 11 for low pass filter)
http://www.synfo.nl/servicemanuals/Roland/SH-1_SERVICE_NOTES.pdf
Very simply my question is: Why?
Why not just have one filter stage? Is it something to do with the resonance? Does it somehow filter the signal better?
I just can't think why one would do such a thing
I've been looking up circuits and chips for a voltage controlled filter, found a great chip: the lm13700, a transconductance op-amp, looks like it will do the job just fine but if you have any suggestions please make them
However, when researching circuits used by synthesizers, they allways seem to have multiple stages in the filter; all the same and all controled by the same control voltage.
Exhibit A: The Roland SH1 filter (see page 11 for low pass filter)
http://www.synfo.nl/servicemanuals/Roland/SH-1_SERVICE_NOTES.pdf
Very simply my question is: Why?
Why not just have one filter stage? Is it something to do with the resonance? Does it somehow filter the signal better?
I just can't think why one would do such a thing