[sdiy] Silly vector synth question

[Richard Wentk]

Component 1 *is* a circle on the hardware. 

I may be getting confused if people are assuming that the diamond/square are the outer limits of the movement. 

They aren't. The path around the edge of the mixer is the in-circle of the diamond, so it's not physically possible to reach 0-100% in both axes all the way around the path.

See e.g. here:

http://biopixmod.com/images/93sshot_1_153f4b8.jpg

So for example if I use Tom's equation when the pointer is at A, I *should* get 1:0:0:0. 

But in fact the joystick is offset inwards from A because it's on the edge of the circle and it can't be moved to A - so I still get a mix of the other oscillators. 

R

On 7 Feb 2011, at 05:22, Tristan wrote:

> I like this idea!
> 
> But if component 1 was represented as a circle rather than a square then you could have an 
> arbitary number of different sources, uniformly or non uniformly distributed, around the circle. 
> Moving the stick around the edge of the circle would give a crossfade between each successive pair 
> of sources. This would be like wavetable/wave sequencing.
> 
> Component 2 would be the sum of each of the sources divided by total number of sources. So 
> moving the stick closer to the centre of the circle would crossfade from the wave mix at that angle 
> on the circle to the sum of all sources, as for vector synthesis. You could also add quirks by adding 
> additional sources to component 2 that are not present on the circle or removing sources present 
> on the circle. Changes in the number of sources in component 2 would require adjusting the divisor 
> accordingly. 
> 
> So for one source on the circle the vector movement would have no effect. For two sources 
> distributed at 180 degrees on the circle you would get a linear crossfade. But for 3 or more sources 
> you would have many interesting vector synthesis possibilities.
> 
> /Tristan
> 
> On Mon, Feb 7th, 2011 at 3:26 PM, Richard Wentk <richard at wentk.com> wrote:
> 
>> I'd guess it works like this:
>> 
>> Component 1 is a simple four axis volume control, with zero in the middle.
>> Pushing the stick N scales the N output from 0 to 1, but with no S.
>> Pushing it S scales from 0 to 1, but with no N. E+W work similarly.
>> 
>> Component 1 gives you the correct mix around the edges, but creates a zone
>> of silence towards the middle. 
>> 
>> Component 2 is a static 0.25*(N+S+E+W) mix of all four components that
>> fills in the zone of silence. 
>> 
>> The relative mix of 1+2 is scaled by the *radius* from the centre
>> position. So when the radius is 0, you get component 2 only, with the
>> correct centre mix. When radius is 1, you get the edge mix from component
>> 1. 
>> 
>> For all other radius values, you get a correct proportional mix of all
>> four components.
>> 
>> Doing the rect to pol conversion is slightly more work, but you only need
>> to do it for each control change. 
>> 
>> I'm not sure linear scaling covers this. At - say - NE, you should get
>> 50:50:0:0. If you use linear scaling, you get some element of W+S mixed
>> in, because the x & y distances from W+S aren't 100%.
>> 
>> R
>> 
> 
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