[HAM] why are tonewheels superior?

[David Anderson]

I've just been doing a recapping of an older generator--actually I'm  
sort of studying it since it's not in an organ--more on that when I'm  
ready.

I haven't noticed a lot of harmonics with the tones, at least from  
49-91, nor have I noticed a lot of trash (though there is certainly  
some), even with the old caps. I have noticed that the tone filters  
closest to the Run motor pick up some hum from the motor windings.

What I *have* noticed is that, due to the original calibration  
process of setting the final output by magnet position, not all the  
waveforms are precisely the same because you have two distances  
involved: the difference between the peaks and valleys on the  
tonewheel and the distance between the tonewheel and the pickup. When  
you move the magnet, you change the ratio of those differences.  
Result: different waveform. Perhaps this random waveform variation is  
partly responsible for the complexity/richness of the tonewheel sound  
(and why not all organs sounded alike even right off the assembly  
line), not to mention the fact that there are some fairly complex  
interactions going on between the loading of the tones by the various  
manual resistance wires and the different taps on the matching  
transformer.

The closer I look, the more interesting it gets....

Tryin' to be scientifical,
David

On Jan 31, 2007, at 10:37 PM, OF wrote:

> To be less flip than my first answer, Mr. Hammond was always  
> disappointed
> that his vaunted tonewheel organ would not do what it was touted to  
> do. The
> "sinusoidal wave" is full of trash. If you have a Hammond and an
> oscilloscope, take a look. Your first two sentences are correct,  
> but that
> in no way leads to the next leap, "harmonic-free fundamentals." And  
> thank
> god it didn't: as others have explained, the idiosyncrasies of the  
> sound
> are what makes the thing great.