[sdiy] Sine-wave VCOs?

[Tony Clark]

   Hi CJ,

> True that for real FFT style synthesis you'd need many. I have a K5M
> which I use for such antics. Too bad its at my parents house now. I
> can't wait to find a K150fs!

   Those are hard to come by!  I'd opt for a K5000S or R (loads of fun 
outside of the monstrous additive application).

> I think you can have much fun with even only a few sines.The DX-7 et al
> are examples of this. Those are digital, but only six operators. Six
> analog sine VCOs is not too much of a project. Even the electribes I'd
> heard often reminded me of a simple two operator FM. Not unlike the
> "second-skin" feature in some of the Simmons drum units.

   I've had much fun with just 3 oscillators.  Of course, having 
different waveforms other than sine is a huge boost to the types of 
sounds you can get.  My first synth was a DX-11 which was 4-op FM, BUT 
had more waveforms than just the sine.  

> Since I never heard of a six sine VCO rack, I assumed there was a
> particular trick to building such a thing. Maybe it's hard to get the
> VCOs to track well? 

   I think the issue is not so much the VCO's, but in order to do good 
FM, you have to have VCAs, and EGs, with each VCO.  So to do a DX-7, 
you'd need the 6 VCO's, 6 VCA's, tons of EG's, etc.  Not terribly 
difficult to do, but most people don't go this route in the analog form 
because of tracking issues.  Even very minor pitch errors can throw off 
complex FM patches!
   The DX-7 only works because the oscillators always start the same, 
track the same, and repeat the same each and every time.  So as Tim said, 
digital is probably the way to go.

   Cheers,

   Tony

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