[sdiy] An Elementary Question: Synths vs Organs

[Roy J. Tellason]

On Saturday 21 February 2009 05:18:00 pm Matthew Smith wrote:
> Hi Folks
>
> Where do organs start and synths end, and vice-versa?
>
> I would like to exclude modern, all-digital gear from this discussion as
> such things probably muddy the waters in this context.
>
> The impression that I get is that an organ generates all the tones at
> once via a top-octave generator, divides them down and then adds them to
> a mix as notes are activated.  

That's accurate up to a point,  but it really depends on the brand and age of 
the organ.  The old Hammonds used additive synthesis for different tones,  
while their later stuff (and that of a lot of others) used square wave or 
ramp outputs taken from dividers and filtered to give the desired tones,  
none of which I was all that impressed with.  And how the heck do you filter 
four or five octaves of "flute" to sound good?

There were some that had a separate oscillator for each tone in the unit,  
though the number of tones was limited.

> Then, with a synth, we have one or a number of tone generators* of definable
> pitch with no fixed note assignment - this being dynamic when notes are
> activated. 

Most synths in my experience were monophonic.  I know there were polyphonic 
instruments out there,  but not very many of them,  and I didn't encounter 
too many of them by the time I stopped working on this stuff for a living 
(1992).  At that point there was a fair amount of that hybrid analog-digital 
stuff out there,  but I didn't see too much of it.

And then there were instruments that combined the features of both.  Some of 
the Wurlitzer organs had a third keyboard,  teeny little keys, essentially a 
very small synth that was more or less independent of the rest of the organ.  
I had a guy once who wanted me to take that out of the organ so he could put 
it in a box by itself,  and as it turned out he was lucky enough that I could 
do just that without much modification at all.

> Is my thinking correct?  If so, here's a bonus question: what do you
> call an instrument where each note has its own dedicated tone generator
> - other than a pain to build and even more of a one to get in tune ;-)

As noted,  I've seen some organs that worked like that.  Aside from 
electronics,  pipe organs worked like that too.  :-)

The one thing you can't do with stuff like that is glide from one note to 
another,  or at least not over much of a range.  Lowrey used to put a little 
tab on one side of the expression pedal that'd bend a note a half step or so 
for that "hawaiian guitar" effect.

-- 
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