Monday, May 4, 2015

Hammond Scanner

I have been reading some interesting things about the rather freaky Hammond Scanner which was for production of vibrato on the Hammond Tone Wheel organs of the 50's & 60's. There is an excellent overview on the ModularSynthesis website. Whilst making one of those is reasonably impractical, despite having a lathe in the shed, I was also interested in the late Jurgen Haible's take on the idea here. I have done a bit of simulation of the important delay line and was also read some more from the ElectricDruid. Tom Wiltshire (the Electric Druid) suggests using all-pass phase shifters in Jurgen's design, this avoids the inductors which are expensive/bulky/prone to electrical pickup. In reality the Inductors look like the way to go. Simulation of all-pass filters shows quite a different response and the inductors aren't too onerous. I am thinking that the way to go with this is to build a board that has Jurgen's delay line but grafts on Oliver Gillets Frames style VCA's under Microprocessor control... It would work out to 4 off 2164 quad VCA's a couple of octal DAC's and a micro controller. Should be able to jam it all onto a Euro sized board as well for a laugh... May mock up a PCB and see how feasible it is...

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