Dual Peak Band Pass Filter
Posted: Mon Jan 20, 2020 8:17 pm
P.S, sorry about the poor image, it was great till I had to shrink it to fit.
Hello Gang,
Well here’s what I am calling my “Dual Peak Band Pass Filter”, yet it is also a “Formant Filter” as well. It’s basically four 12db state variable filters, two each in series for 24db each. The two 24db filters are both set for lowpass out only and both have their own cut off and resonance controls. When combined by subtraction this gives us a 24db Band Pass filter where each peak can be moved independently of the other and also resonance. Also added is a master center frequency control that moves both peaks in unison. See the images for a better understanding. You can select either 12db or 24db output via the little 12db/24db button and also there is a separate 12db output. The little blue slide switches marked 12db O.S. (offset) add a frequency offset to both the 12db filters and act like fine tuning for each peaks center frequency. The button marked “invert peak 1” in most cases boots the frequency response. There is of course the “FFT Spectrum Display”, that really helps setting up various peak separations (responses). Last, take the time to really play with all the setting, as it can provide a lot of really nice sounds, from standard 24db Band Pass, to unconventional Band Pass, and fun vowel Formant sounds.
NOTE; some settings of high resonance along the low and high frequency can cause feedback like howling. Watch those speakers!
Please, enjoy and leave comments or any mods you would like to suggest!
Later then, BobF…..
Well here’s what I am calling my “Dual Peak Band Pass Filter”, yet it is also a “Formant Filter” as well. It’s basically four 12db state variable filters, two each in series for 24db each. The two 24db filters are both set for lowpass out only and both have their own cut off and resonance controls. When combined by subtraction this gives us a 24db Band Pass filter where each peak can be moved independently of the other and also resonance. Also added is a master center frequency control that moves both peaks in unison. See the images for a better understanding. You can select either 12db or 24db output via the little 12db/24db button and also there is a separate 12db output. The little blue slide switches marked 12db O.S. (offset) add a frequency offset to both the 12db filters and act like fine tuning for each peaks center frequency. The button marked “invert peak 1” in most cases boots the frequency response. There is of course the “FFT Spectrum Display”, that really helps setting up various peak separations (responses). Last, take the time to really play with all the setting, as it can provide a lot of really nice sounds, from standard 24db Band Pass, to unconventional Band Pass, and fun vowel Formant sounds.
NOTE; some settings of high resonance along the low and high frequency can cause feedback like howling. Watch those speakers!
Please, enjoy and leave comments or any mods you would like to suggest!
Later then, BobF…..