[sdiy] SAW core VCO flyback time

[Tom Wiltshire]

On 28 Aug 2016, at 10:40, Mattias Rickardsson <mr at analogue.org> wrote:

> On 28 August 2016 at 06:11, Adam Inglis <21pointy at tpg.com.au> wrote:
>> On 28 Aug 2016, at 2:27 am, Mattias Rickardsson <mr at analogue.org> wrote:
>> 
>> But regarding the sound - I made a very bad (meaning slow flyback) saw
>> core, and now people shout that it sounds so great and they want it in
>> more designs.
>> 
>> That’s very interesting.
>> What is the sonic appeal?
> 
> I'd guess it's either the "warmer" sound of the not-so-sharp edges, or
> the imperfections in detune between oscillators since they are not
> very linearly controlled towards the low end.

You can see the way that increasing amounts of flyback time affect the harmonic structure on this page:

http://electricdruid.net/timbral-evolution-harmonic-analysis-of-classic-synth-sounds/

The bit you want is titled "Ramp-down/Triangle/Ramp-up" in the Phase Distortion section abut half-way down. Up to about 10%, the effect is pretty much a soft roll-off of the higher harmonics, coupled with a relative boost to the fundamental and second harmonic.