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KOACH · FUNs · Level 5 · Hidden LFOs · Lesson 13 of 14

a|y|+b

recursions= y = a × |y| + b, every 20 ms

A recursive generator on the size of the last output: |y| times a, 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 feedback; b: the step.

OUTPUT RANGE

−1..+1, wrapping round from +1 to −1

USE IT FOR

With a below 1 it settles (a 0.5, b 0.5: 1); with a = ON it climbs by b, wraps, and then sticks between two values (-1 and -0.8 with b 0.2): odd stepped patterns rather than a clean ramp.

WATCH OUT

It works on the size of the last output, so after a wrap it can stick between two values: −1 and −0.8 with a = ON and b 0.2.

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 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 0.50 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 a|y|+b.

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

  5. Hold a note: LFO1 comes out lopsided, its upper half doubled (and wrapping round past +1), its lower half shrunk to two thirds.

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