Synthacon filters are up and running
2004-05-10 by Richard Brewster
I finally got the dual Synthacon module all put together this weekend.
It is a unique filter. The band pass, especially. If you don't build
two, then you won't realize how, even with all the parts nominally the
same, two Synthacon filters will have different characteristics. It
must be differences in the gain of the transistors. I notice different
VC gain and different resonance pot response between the two. One
sounds "healthier" or "fatter" than the other, somehow. But both are
good. The "wimpier" sounding one shows an interesting pitch-change
effect. When the cutoff frequency is modulated upward by an envelope
(but the input VCO frequency held constant) the pitch seems to go a
little flat. This only happens on the one filter. I have no idea what
causes this effect. (I need to read up on pitch perception in
Electronotes.)
I made a patch using the two Synthacons and also my two new CGS VCOs.
I've uploaded an MP3 to the files section on Yahoo. The signal path of
this patch is from the square wave outputs of the VCOs to the Band Pass
inputs of the Synthacons. The Synthacon outputs are then mixed and
recorded. The Synthacon frequencies are modulated by envelopes that
change in period semi-randomly. This is an auto-running patch (no knobs
touched during recording). The VCO pitches are controlled by two
Infinite Melody outputs, quantified by two Miniwaves.
-Richard Brewster
It is a unique filter. The band pass, especially. If you don't build
two, then you won't realize how, even with all the parts nominally the
same, two Synthacon filters will have different characteristics. It
must be differences in the gain of the transistors. I notice different
VC gain and different resonance pot response between the two. One
sounds "healthier" or "fatter" than the other, somehow. But both are
good. The "wimpier" sounding one shows an interesting pitch-change
effect. When the cutoff frequency is modulated upward by an envelope
(but the input VCO frequency held constant) the pitch seems to go a
little flat. This only happens on the one filter. I have no idea what
causes this effect. (I need to read up on pitch perception in
Electronotes.)
I made a patch using the two Synthacons and also my two new CGS VCOs.
I've uploaded an MP3 to the files section on Yahoo. The signal path of
this patch is from the square wave outputs of the VCOs to the Band Pass
inputs of the Synthacons. The Synthacon outputs are then mixed and
recorded. The Synthacon frequencies are modulated by envelopes that
change in period semi-randomly. This is an auto-running patch (no knobs
touched during recording). The VCO pitches are controlled by two
Infinite Melody outputs, quantified by two Miniwaves.
-Richard Brewster