I’m working on modeling the Serge Equalizer. I’ve modified the frequency bands to match the original but I’m at a bit of a loss regarding the “resonant” aspect. Generally when a filter is referred to as resonant, it exhibits a response peak around the center or cutoff frequency. In this case, the filters are peaking eq type filters so they all exhibit a response peak when the gain at the center frequency is > 1. In that sense all equalizers are already resonant. In the description of the unit it states that:
“When the knobs are positioned between the 9 and 3 o’clock position, up to 12 db of boost or cut is set at the band. If the knob is set beyond the 3 o’clock position, the band will become resonant, simulating the natural resonance of acoustic instrument formant structures. Below the 9 o’clock position, increased band rejection is achieved.”
After thinking about this I’m not really sure what it means. Does the boost or cut simply become more intense? With a peaking eq style filter the Q (which is typically a measure of resonance) and the bandwidth are inversely proportional. Are they implying that the bandwidth of the frequency band narrows as you increase the control past the 3 - 9 o’clock position? Does anyone have any experience with this type of filter? I haven’t been able to find a more detailed description so at this point I’m just guessing. I’m thinking that the bandwidth must become narrower which would create a more defined peak.