[sdiy] Hammonds (was: Programmable Logic?)

[Tim Parkhurst]

Again, I still think the biggest challenge in electronically duplicating a
Hammond is this: Where do you stick the knives?


Cheers!

Tim (first love was also an organ...) Servo

"Imagination is more important than knowledge." - Albert Einstein




> -----Original Message-----
> From: Gene Stopp [mailto:gene at ixiacom.com]
> Sent: Tuesday, July 20, 2004 11:15 AM
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] Hammonds (was: Programmable Logic?)
> 
> The Hammond organ is really my first love, even before the Moog. So me
being
> me, I've had my hands in the guts of many, many Hammonds, minor repairs,
> complete restorations of gutted chop-jobs, etc. I've been *so* down this
> philosophical road before! Here's my list of challenges in Hammond sound
> synthesis:
> 
> The Electronic Challenge:
> 
> * Duplication of the frequencies of the tone generator, including the
> various beat frequencies and jitters
> 
> * Duplication of the waveforms from all the tonewheels - they're not going
> to be perfect sinewaves, in fact some tomewheels have intentional
> harmonic-adding teeth
> 
> * Duplication of 9 contacts closing at different times when a key is
> depressed (which adds a bit of velocity-determined variation)
> 
> * Duplication of the crosstalk from millivolt-level tones traveling in
> bundled cable harnesses
> 
> * Duplication of the frequency response and distortions of the signal
chain
> 
> * Duplication of the amplitude decay curve in the percussion circuit
> 
> * Duplication of the tremolo, vibrato and chorus characteristics - lots of
> variations here, the first Hammonds had mechanical tremolo, then the "V"'s
> had scanner vibrato, which carried over into the B2/C2/B3/C3 and their
> variants (RT's, A-100's, etc.), then the "L"'s had electronic vibrato,
etc.
> 
> The Subjective Challenge:
> 
> * Duplication of the physical characteristics of the waterfall keys on the
> manuals, which influences playing style
> 
> * Duplication of the weight of the machine, whose rock-steady presence
leads
> to getting carried away with your body movement when you're really
"rocking
> out"
> 
> * Duplication of the smell of grandma's living room dust burning on the
> tubes, old wood and oil, and cloth wire insulation
> 
> All of this is before you even get to the spring reverb stuff, and the
> Leslie stuff is a complete subject of its own. I think there are two
> approaches to getting the Hammond sound - the "thrill of the hunt", so to
> speak, which is the synthesis of the above (or most of them, anyway), or
the
> "Real thing" which is finding a real Hammond (and the room for it!).
> 
> Latest Hammond project was the stacking of a Leslie 125 on top of a 147,
> slaving their motors together with solid state relays, and plopping a tube
> amp head on top (Fender 140) which drives all the drivers. So I have this
> seven-foot-tall stack with reverb and EQ, 140 watts of 6L6 power,
extremely
> grungy and rude when running with an old CV with a home-brew percussion
> circuit. I usually only mess with it for a few minutes at a time, long
> enough for the neighbors to rush out of their houses wondering what the
heck
> was going on. Afterwards I have to make nice with my wife.
> 
> 
> - Gene
> 
> 
> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of James Patchell
> Sent: Tuesday, July 20, 2004 10:19 AM
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] Programmable Logic?
> 
> 
> Very interesting....I can see that it is maybe even more complicated than
I
> imagined...
> 
> 
> At 08:03 AM 7/20/2004 -0700, Tim Ressel wrote:
> >Yo,
> >
> >
> >Ah, gearboxes. As it happens I have a bit of
> >experience with this kind of thing. I worked at a
> >place that was doing spectrums of gearbox vibrations
> >to determine driveline health. Basically what you'll
> >see in a gear train like the Hammond tomewheel setup
> >is frequency (or phase) modulations from various
> >sources. Any gear has a 'pitch circle' which
> >more-or-less the middle of the gear teeth. Nothing to
> >do with musical pitch; but an amusing coincidence.
> >
> >See:
> >http://shopswarf.orcon.net.nz/spur.html
> 
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