[sdiy] Scanner Chorus pcb interest?

[Mike Beauchamp]

Hey Dave, I was thinking the same thing as soon as I read this post...
Getting a hammond scanner and actually rigging it up. I'd like it as a
guitar pedal personally....

This emulation thing sounds like a great project as well.

Mike

On 7/6/07, David Brown <davebr at earthlink.net> wrote:
> I was always thinking of just buying a Hammond scanner and making an outboard box.  You see them from time to time on eBay.  It's been a while since I looked in the back of my Hammond, but I'm guessing all the inductors were external to the scanner and mounted somewhere else.
>
> Looking forward to the future MOTM-like module.  My other mechanical project that is still sitting on the workbench as parts is a Raymond Scott Circle Machine.  I have the stepper motor, controller, and AVR all ready to program.  Just never quite started the bearings and mechanism.  Seems like you need at least one mechanical module for a synth.
>
> Dave
>
> -----Original Message-----
> >From: "JH." <jhaible at debitel.net>
> >Sent: Jul 6, 2007 3:01 PM
> >To: synth-diy at dropmix.xs4all.nl, analog heaven <analogue at hyperreal.org>, MOTM List <motm at yahoogroups.com>
> >Subject: [sdiy] Scanner Chorus pcb interest?
> >
> > 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.
> >
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