The Four-Corner Crossfade
Put four sounds at the corners of a square. Drag a dot around and they blend together. That's vector synthesis.
The idea comes from the Sequential Circuits Prophet VS (1986) and Korg's Wavestation. You pick a different waveform for each corner, then move a joystick to mix between them. Closer to a corner means more of that sound.
The gain meters show exactly how much of each corner you're hearing at any position. At the center, all four contribute equally. At any corner, that oscillator plays solo.
Hit Play, turn on the Arp, and drag the dot around. Change the corner waveforms to hear how different combinations blend.
How It Works
Each corner's volume depends on how close the dot is to it. The four gains always add up to 100%. Move to a corner and that oscillator plays solo. Move to the center and all four share equally at 25%.
The math is called bilinear interpolation. If you know the dot's x and y position (both 0 to 1), corner A gets (1-x)(1-y), B gets x(1-y), C gets (1-x)y, and D gets xy. Simple, but it gives you smooth morphing in every direction.
References
- Vector synthesis - Wikipedia
- Sequential Circuits Prophet VS - Wikipedia