Scanner Chorus pcb interest?
2007-07-06 by JH.
Thinking about future pcb projects ... One thing I wanted to do for a long time is a stereo chorus based on my electronic emulation of the Hammond Scanner Vibrato. I've built something like that a few years ago: http://jhaible.heim.at/scanner_vibrato/jh_scanner_vibrato.html This was purely intended to be an emulation of the Hammond Chorus/Vibrato effect, but I always thought it would also make an interesting, more general, and stereo, chorus device. That would be a "true analogue" chorus in a different sense than the BBD-based effects, because the signal is not sampled. It's not free of side effects, thou. It has a somewhat rough modulation waveform, as instead of changing a delay time continuously, it interpolates between 9 taps of a 1ms analogue delay line. It's a linear interpolation, not a switching - best thing is you listen to the sound samples and decide for yourself. It's very rough (in a Hammond-ish way!) for vibrato, and increasingly smoother when the dry signal is mixed in for chorus. It's a quite complicated method to crate a simple chorus, compared to a BBD circuit. It requires a 50-pole (fifty!) low pass filter, but that can easily be built from 25 cheap inductors (less than a dollar per piece at Mouser) and 25 capacitors. On the positive side, it's a lot more "direct" sounding than a BBD-based (or digital delay based) chorus, as the maximum delay time thru the whole circuit is only 1ms. (Speak of latency ...) If there's enough interest, this could be a project for a future PCB development. I wouldn't restrict this to Hammond emulation, but make a mono-in / stereo out device in the fashion of many Roland / Boss dual-BBD chorus circuits. Just without BBD. Let me know what you think ... JH. PS: this is not to be confused with my Interpolating Scanner, which is planned to be a future MOTM module.