[sdiy] hammond again

[Gene Stopp]

I'm not sure how to quantify this either! Perhaps a scope connected to some
generator outputs, visible from the front of the Hammond, and then play some
heavy chords using those tones? I've not detected any effect before, but
perhaps it's too subtle and gets masked by the Leslie? This is a fascinating
new twist on the analysis on why Hammonds sound the way they do. Juergen,
you are always so good at this. Maybe some day I'll get the chance to
experiment with this. I can see my wife now - "what the heck are you doing?"
:)

Message to Harry - I heartily recommend finding an old Hammond. Ebay can be
useful for this, but you must "search without trying" and one may fall into
your lap (ouch!). Geographics plays into this, since the sellers rarely say
anything other than "come and get it, you sucker". However without a garage
it's a bit of a space-stealer, and if you have stairs, well that's another
issue :)

For some younger people the lure of the Hammond may be a mystery. For old
farts like me who grew up listening to Steppenwolf et al, there is a certain
charm to the beasts. Something about the smell of dust baking on the tubes,
the smell of the old wood and generator oil, the fabric-insulated wires, and
of course the sheer weight of the machine (so that it doesn't even wiggle if
you get a little too "inspired" whilst playing).

In the past I have considered what it would take to build a clone - start
with a top octave generator, divide it down to get the whole range of
frequencies, use passive R/C filters and some buffers to get it all down to
sinewaves, then wire it up to a 9-bus keyboard. The busses get sent to
drawbars for mixing. If a 9-bus keyboard isn't available, you could use
analog switches in banks to do the contact simulation. But wait - add up all
the time and energy! Much easier to find an old machine that already has it
all. Not only that, the contacts don't close at the same time! And also,
real metal contacts running at millivolt levels make a popping noise! And
the frequencies from a top-octave generator aren't the same! The Hammond is
a great example of the "it's just not the same" syndrome.

This brings up something more - why do these machines cut through the mix so
well in a live situation? Oops, this is another topic, but one that I'd like
to discuss.

- Gene


-----Original Message-----
From: jhaible at debitel.net [mailto:jhaible at debitel.net]
Sent: Tuesday, November 05, 2002 7:05 AM
To: synth-diy at dropmix.xs4all.nl
Cc: jhaible at debitel.net
Subject: [sdiy] hammond again


Thanks to all who replied, on-list and off-list.

I think I wasn't clear enough about this. 
I was neither talking about slow lesley effect / chorus vibrato, nor
did I expect any effect back to the motor.

I was talking about the tonwheel / pickup system, back to a
mechanical junction where there is no stiff coupling to the motor.
I think there is a resilent part in there somewhere, which would
certainly form a system which can "oscillate" against its nominal
rotation. Also, a sudden loading of the system will certainly cause
such oscillation, if ever so tiny.

My question is: would this be a *perceivable* effect??
I have no idea how to quantify this.

Again, what I was talking about was not a "chorus" type of sound.
It's more like "liquid" versus "dry".
The funny thing is that samples of a tonewheel organ often *have* this
liquid character, but an electronic drawbar organ doesn't have it.

JH.