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KOACH · FUNs · Level 5 · Hidden LFOs · Lesson 12 of 14

y+a(y+b)

recursions= y = y + a × (y + b), every 20 ms

A recursive generator: the last output plus a share a of the last output plus b. Like the other y-equations it can cycle like an LFO or turn chaotic, depending on the inputs.

SEE IT MOVE

SCOPE · LAST 2 S
THE WAVE · LAST 8 S
a0.00
b0.00
OUTPUT0.00

Computed in your browser with KINSPIRATION's FUN engine, step by step: this FUN keeps a state, so its output depends on what came before.

WHAT TO KNOW

INPUTS

a: the growth (0 holds, negative damps); b: the offset.

OUTPUT RANGE

−1..+1, wrapping round from +1 to −1

USE IT FOR

a = 0 holds y; a negative a settles at -b (a -0.5, b 0.5: -0.5); a positive a runs away and wraps into irregular patterns.

WATCH OUT

a = 0 holds y where it is; a negative a settles at −b, faster the further it is from 0; a positive a runs away.

IN THE FACTORY PROGRAMS

No factory program uses it: one of the K2700's hidden tools.

HOW TO ON YOUR K2700 · 2046 Editor Template

The factory does not route y+a(y+b) to a sound on its own: set one up on 2046 Editor Template and hear it on the pitch.

  1. In Program mode choose 2046 Editor Template, a plain one-layer program to build on (KEYPAD, 2046, ENTER).

    Program mode with 2046 Editor Template

  2. Press EDIT, then MORE and DSP MOD. On the Pitch row set Source 1 to FUN2 and its Depth to 1200 ct: FUN2's result, −1 to +1, now bends the pitch up to an octave either way.

    The DSP MOD page of 2046 Editor Template, layer 1, the cursor on Depth (1200 ct)

  3. MORE, then LFO+. On the FUN2 row set Input a to -0.05 and Input b to LFO1.

    The LFO+ page of 2046 Editor Template, layer 1, the cursor on Input b (LFO1)

  4. Move to Function and turn the Alpha Wheel to y+a(y+b).

    The LFO+ page of 2046 Editor Template, layer 1, the cursor on Function (y+a(y+b))

  5. Hold a note: the pitch follows LFO1 upside down and late, y moving 5 % of the way toward −LFO1 every 20 ms: a lag that also turns its source round.

  6. Press EXIT and answer NO to leave the factory program as it was, or SAVE to keep your version on a USER ID.