Path Filter
Description/Usage
8hp
This module sits somewhere between a filter, a phaser, and a crude BBD analogue shift register. It was inspired by an article on phasing with path filters in Sept 1975 Elektor, but the circuit is a very different approach to the one suggested. This picture from the article gives the basic idea. The resistor sets the band width or Q, which is set by pots and a vactrol in this module. This version has 16 capacitor/switch stages, along with buffered inputs and outputs and a feedback stage via the switch pin of input 2 and an attenuverter.
The module requires a clock to start and run, usually this will be a very high frequency signal (20kHz – 100kHz), but feel free to experiment. Of course, modulating the clock source with CV is a good thing to do. The divided down frequencies of the clock signal are available on the panel (/4, /8, /16), with /16 connected to the switch on IN 1. For me, it is far more interesting to experiment with different input signals.
Q Range sets the regions where the Q signal can travel. Q and Q CV control the vactrol. If you want a wider range, replace the 10k Pot with 20k, 50k or even 100k. I initially installed a 100k pot but found I was only using it in the 0-2 region, so went for 10k and am happy with it.
The IN 2/FB pot, when used for feedback, is most effective in the 0-5 range, 5 = off = no feedback. You may find uses for the higher levels. If you wish to increase the feedback signal, change the 100k indicated below to a lower value. At 51k, the signal is turned off and goes to the -12V rail when the pot is at 0, so probably keep your experimenting in the 68k to 100k range, or just be happy with 100k.
How does it sound? You need to find the sweet spots with the clock frequency, which is not hard; once you are there it is sounds like nothing else
DG408 are available in the PARTS section
DIY
Description/Usage
8hp
This module sits somewhere between a filter, a phaser, and a crude BBD analogue shift register. It was inspired by an article on phasing with path filters in Sept 1975 Elektor, but the circuit is a very different approach to the one suggested. This picture from the article gives the basic idea. The resistor sets the band width or Q, which is set by pots and a vactrol in this module. This version has 16 capacitor/switch stages, along with buffered inputs and outputs and a feedback stage via the switch pin of input 2 and an attenuverter.
The module requires a clock to start and run, usually this will be a very high frequency signal (20kHz – 100kHz), but feel free to experiment. Of course, modulating the clock source with CV is a good thing to do. The divided down frequencies of the clock signal are available on the panel (/4, /8, /16), with /16 connected to the switch on IN 1. For me, it is far more interesting to experiment with different input signals.
Q Range sets the regions where the Q signal can travel. Q and Q CV control the vactrol. If you want a wider range, replace the 10k Pot with 20k, 50k or even 100k. I initially installed a 100k pot but found I was only using it in the 0-2 region, so went for 10k and am happy with it.
The IN 2/FB pot, when used for feedback, is most effective in the 0-5 range, 5 = off = no feedback. You may find uses for the higher levels. If you wish to increase the feedback signal, change the 100k indicated below to a lower value. At 51k, the signal is turned off and goes to the -12V rail when the pot is at 0, so probably keep your experimenting in the 68k to 100k range, or just be happy with 100k.
How does it sound? You need to find the sweet spots with the clock frequency, which is not hard; once you are there it is sounds like nothing else
DG408 are available in the PARTS section
DIY
Description/Usage
8hp
This module sits somewhere between a filter, a phaser, and a crude BBD analogue shift register. It was inspired by an article on phasing with path filters in Sept 1975 Elektor, but the circuit is a very different approach to the one suggested. This picture from the article gives the basic idea. The resistor sets the band width or Q, which is set by pots and a vactrol in this module. This version has 16 capacitor/switch stages, along with buffered inputs and outputs and a feedback stage via the switch pin of input 2 and an attenuverter.
The module requires a clock to start and run, usually this will be a very high frequency signal (20kHz – 100kHz), but feel free to experiment. Of course, modulating the clock source with CV is a good thing to do. The divided down frequencies of the clock signal are available on the panel (/4, /8, /16), with /16 connected to the switch on IN 1. For me, it is far more interesting to experiment with different input signals.
Q Range sets the regions where the Q signal can travel. Q and Q CV control the vactrol. If you want a wider range, replace the 10k Pot with 20k, 50k or even 100k. I initially installed a 100k pot but found I was only using it in the 0-2 region, so went for 10k and am happy with it.
The IN 2/FB pot, when used for feedback, is most effective in the 0-5 range, 5 = off = no feedback. You may find uses for the higher levels. If you wish to increase the feedback signal, change the 100k indicated below to a lower value. At 51k, the signal is turned off and goes to the -12V rail when the pot is at 0, so probably keep your experimenting in the 68k to 100k range, or just be happy with 100k.
How does it sound? You need to find the sweet spots with the clock frequency, which is not hard; once you are there it is sounds like nothing else
DG408 are available in the PARTS section