[music-dsp] Hammond Organ Modeling

[James Chandler Jr LapG4]

> I am very happy to say that we may be very lucky to
> be given in a very near future, an old Hammond
> Organ from 1940 ! I am planning to do series of
> recordings of sounds, but also electronic and
> even magnetic signals when I have more time,
> most probably over the summer.

Hi Brahim

Congrats on the Hammond.

You may get very lucky with that vintage-- around 1940 (I think) 
Hammond made a dual-generator version. Am not exactly certain what 
these models were called-- I think it was either a model A or D. It was 
historically right before Hammond introduced the scanner vibrato/chorus 
circuit in the C and B models.

It is the favorite model I've seen, but have only seen three instances. 
One was not for sale (but was wonderful to play), and the other two 
instances were in too bad condition to practically refurbish (unless 
one wanted to launch a very long-term hobby).

I was given the parts for one of them, but after ten years of gazing at 
them on the floor of the shop and thinking about all the work to put 
them in a cabinet, rewire and refurbish, finally junked the parts.

It had a "long" generator with the usual number of tonewheels, and a 
second "short" generator with fewer tonewheels. Each tonewheel in the 
"short" generator had "split" tonewheels with dual sets of teeth to 
generate tones slightly sharp/flat from the main generator. It would 
beat the main generator against the chorus generator to make a very 
rich sound.

This model had a Tremulant (amplitude tremolo) scanner rather than a 
vibrato/chorus delay line scanner. No percussion, and only two tubes-- 
a rectifier tube and a preamp tube.

Externally it can be identified by a Tremulant slider on the upper 
right of the console, and a chorus switch or slider rather than the six 
position vibrato/chorus knob.

Wonderful sound. The only drawback, was that the side edges of the keys 
were very "sharp". It was painful to do much side-of-the-hand 
glissandos or smears on this keyboard. With such a model, would be 
worth taking a moto-tool to the keys and slightly round off the edges.

James Chandler Jr.