[sdiy] 60s organ sound

[WeAreAs1 at aol.com]

In a message dated 12/9/04 2:39:08 PM, torpedo at demadrid.com writes:

<<  What I mean is, what sort of waveforms did they use in the oscillators? 
What shape does the vibrato waveform have? which filters should be used?...  >>

Most of them start with square waves and run those through fixed-frequency 
lowpass filters to get a sort of sine wave-like sound.  It's that Sine-like 
sound that you hear.  However, some of them start with sine waves -- that's the 
exception rather than the rule, though.

Filtered squares (without any filter resonance) will get you halfway there.  
If you have the ability to make sines or triangles on your synth, then those 
waves can also be useful.

Keep in mind that all organ sounds are made up of multiple harmonics that are 
mixed together -- the drawbars on a Hammond organ are actually a little 
9-channel mixer.  The Vox Jaguar and Continental also had drawbars with several 
harmonics that could be mixed.  The first four or five drawbars on the Vox gave 
you the first through fourth harmonics (sine-ish waves), and the last drawbar 
was a premix of the higher harmonics, which could be added to give the organ 
its characteristic edge (think of the organ solo in the Doors "Light My Fire", 
which really displays that classic Vox sound beautifully.  And no, the original 
studio recording of Light My Fire was not played on the Gibson organ -- it 
was definitely the Vox Continental...)  

It's hard to get a true combo organ sound with just two VCO's -- it works 
much better with three or four, but you can get close if you work at it.  Try 
tuning your two VCO's two octave apart (and sync them if you can).  If your synth 
has a suboctave function (like the Roland SH-101), then those suboctaves can 
be very useful for emulating combo organ sounds.  Indeed, that's exactly how 
real combo organs generate all of their notes except for the very highest 
harmonics, by using divide-down circuits (same as a typical suboctave circuit on a 
synth).  Make sure your VCA envelpoe is set to the simple "organ envelope" 
shape (fast attack, no decay, full sustain, no release).  Don't use any filter 
envelope modulation, period.

The Farfisa organs have a characteristically more "reedy" sound than the Vox, 
mostly because they don't filter the initial square waves as much as in the 
Vox organs.  As a result, the Farfisas sound a little more buzzy and edgy than 
the Voxes.  They're both great sounds, though.  If you want to emulate the 
Farfisa sound, try using square waves and leave the filter a bit more open.  
Also, you can layer a second VCO tuned an octave and a fifth higher than the first 
VCO to get the classic buzzy Farfisa sound.  The Voxes had that fifth too 
(the third harmonic), but they don't bring it in as strong, and it's more 
filtered, so it's smoother sound.

One more thing, if you can sync your oscilators, you should do so.  If you 
don't sync them, the drift and phasing between the VCO's will make it sound more 
like a synth and less like an organ (organs of this type have all of their 
partials in phase with each other at all times).

The vibrato oscillators in combo organs were almost always sine waves.  A 
little vibrato goes a long way -- get the sound you want from the VCO's and 
filters before you start adding vibrato, because it's not cheesy wide vibrato that 
made combo organs so cool -- it was their basic tone and waveshapes (I don't 
think Ray Manzerek ever once used vibrato on anything he ever recorded with the 
Doors; he just liked that plaintive, straight, very electronic sound).  A 
triangle LFO will work 95% as well as a sine LFO for this purpose.  Good luck!