[sdiy] Additive VCO

[Mark Smith]

I looked into this some time ago and shyed away from the analogue vcos. I decided to have a go a primitive additive synth just using a high speed vco input and dividing this down and then summing different amplitude and harmonics together.
I did an exel spreadsheet to view the waveforms, and pick what looked interesting.

I found that with just two 16 way switches I could get a reasonable range of waves from sqr to saw. Some were quite cool, but after a while the lack of even harmonics drove me mad and I abandoned it in favour of subtractive synths....

I now look back and realise it does look very walshlike, but not half as complex.

schematic is here:    http://www.meadowfield.freeuk.com/synth/dig_osc.pdf

mark

> -----Original Message-----
> From:	M.A. Koot [SMTP:makoot at gmx.net]
> Sent:	Monday, March 08, 2004 1:51 PM
> To:	synth-diy at dropmix.xs4all.nl
> Subject:	Re: [sdiy] Additive VCO
> 
> Thanks everyone for the kind feedback.
> 
> I'm still just a student doing electronics/mechatronics, so I'm pretty
> unexperienced and of coarse: it's just an idea I had. 
> I like a lot of the other ideas here, it's a good thing the harmonics may be
> drifting a little bit, saves a lot of trouble.
> As I see, it seems to be pretty utopic to try and create a signal from
> analog Sine's, but since I have even less experience in programming DSP's, I'd
> still like to try it analog.
> I'll look at the triangle-splitters, it sounds really interesting! But
> Theo's Pulse-devider is interesting also, although I dont' know if indeed the
> harmonics would get too static.
> I guess I'll have to trial and error to find out the best way.
> 
> Another feature I might like to add is single VCA's for every hamonic.
> That'd be a lot of work, but it would be very nice I think if you would be able to
> change every single harmonic amplitude over time using envelopes etc. That's
> something I could look at after the actual sine production of coarse..
> 
>