DRP FILTER
Posted: Wed Sep 20, 2017 7:38 pm
RingingExample.rar- (288.92 KiB) Downloaded 923 times
- BobsDRP Filter.fsm
- (642.23 KiB) Downloaded 955 times
Hello gang,
Here is a new filter I built called the DRP Filter, short for Double Resonance Peak Filter. In essence there are two independent filters in parallel (inputs A and B), only sharing the resonance knob and with their outputs mixed in either a subtraction or addition mode. For example if both filters get the same input signal, the low pass mode set to the lowest cutoff is subtracted (subtraction mode) from the low pass mode with the highest cutoff and this creates a bandpass response that only passes what is between the two cutoff frequency settings. This is only one example of many, many possible combinations. By viewing the analysis graph you can set many different responses of your own design. Besides the standard LP, HP, BP, Notch, and Peaking responses, I have also added Formant (great for vowel and voice tones) and Comb (each comb response can independently be inverted). Both filters cutoff frequencies can also be swept independent of each other. There are two knobs labeled, “Mix A to B’ and “Mix B to A”. They do just that, mix input A to input B and mix input B to input A. This allows even more response variations to experiment with. Another cool feature I add is to set the resonance knob for higher Q’s. This allows the filters to be pinged. That is, if a slow square wave, pulse, oneshot, and so on is applied to the input with the resonance all the way up, the filter will ring, giving bell, string, and percussion type tones. Listen to the supplied RingingExample.mp3 (rar file). Last the graph gain slider just sets the gain to the display for best viewing. The scope displays the mixed subtracted or added waveforms. For anyone wishing to use it in a Synth, you can of course remove the analysis and scope displays if you like.
Enjoy, and if you have any suggestions to make it better or find any problems, PLEASE let me know.
Till next time, BobF…..
