[sdiy] Hammond Organ Query

[phillip m gallo]

"Sound generation in the Hammond B3 comes from within what is known as the
main generator. A long drive shaft, driven by an AC synchronous motor, runs
the entire length of the main generator. From that shaft is connected 24
driving gears, with 12 different gear sizes total. These 24 driving gears
are connected to 2 more gears, made of bakelite. These bakelite gears each
have their own shaft, and mounted to that same shaft is the tone wheel.
There are 12 different sizes of bakelite gears. These gear ratios provide
the proper speed (pitch) for the tone wheel to be in tune with one another.

The tone wheels are steel discs about 2 inches in diameter. These discs are
machined with high and low points known as teeth. The number of teeth vary
in relation to the tone trying to be produced. The basis of the tone is the
equal tempered scale. "

http://www.rimboy.com/hammond/




-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Tim Ressel
Sent: Friday, October 25, 2002 12:38 PM
To: patchell
Cc: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Hammond Organ Query


By gear ratios, I meant the ratios bewteen the gears.
In just ntonation, the ratioes are like 5/4, 3/2, etc.
Real simple. In equal temperment, the ratios are
multiples of 1.0594631...  Not easy to get with gears.

--TR


--- patchell <patchell at silcom.com> wrote:
>     It would be just like making a top octave
> generator with digital
> logic.  You would have a set of magic division
> ratios that you would use
> to approximate equal temperment.
>
> Tim Ressel wrote:
>
> > Mass Brain Query:
> >
> > On the Hammond organ the tone generators were
> > gear-tooth wheels ... so like, does it use
> > just-intonation? Seems like it would have to so
> the
> > ratios come out even. Equal temperment (an ironic
> term
> > to use with this crowd :-) generates all these
> nasty
> > irrational numbers that would be difficult to make
> > with gear ratios.
> >
> > ?????
> >
> > --TR
> >
> > __________________________________________________
> > Do you Yahoo!?
> > Y! Web Hosting - Let the expert host your web site
> > http://webhosting.yahoo.com/
>
> --
>  -Jim
> ------------------------------------------------
> * Visit:http://www.silcom.com/~patchell/
> *-----------------------------------------------
> *I'm sure glad Merry Christmas comes just once a
> year
> * -Yogi Yorgensen
> ------------------------------------------------
>
>


__________________________________________________
Do you Yahoo!?
Y! Web Hosting - Let the expert host your web site
http://webhosting.yahoo.com/
---
Incoming mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.404 / Virus Database: 228 - Release Date: 10/15/02

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.404 / Virus Database: 228 - Release Date: 10/15/02