# J and S Curves

Several of the DHE Modules apply a curved transfer function to produce their output. The transfer function comes in two shapes:

Stage and Booster Stage can generate J-shaped envelope stages. In addition, Booster Stage can generate S-shaped stages.

Swave can apply a J- or S-shaped transfer function to shape its input.

Tapers can apply a J- or S-shaped taper to the position of its LEVEL knob.

Each module has a knob that determines the sign (positive or negative) and magnitude of the curvature. Positive curvature creates a J or S shape. Negative curvature inverts the shape. Extreme curvature (positive or negative) creates a curve so sharp as to be nearly square.

Each transfer function (J or S, positive or negative) is produced by Dino Dini’s beautiful normalized tunable sigmoid function.

# J Curves

## Positive J Curves

Rotating the CURVE knob clockwise from the center pushes the steep part of the curve to the right.

Note: Extreme positive curvature makes the curve almost square at the end.

## Negative J Curves

Rotating the CURVE knob counterclockwise from the center pushes the steep part of the curve to the left.

Notes:

• Each curve actually starts at the same voltage. But as the curvature becomes more negative, the rise is so fast that the Scope can’t display the initial value.
• With the knob fully counterclockwise, the rise is so fast that the Scope can’t show it at all. That’s why there’s no image.
• Extreme positive curvature makes the curve almost square at the start. Given that there’s no image, you’ll have to trust me about this. Or try it yourself.

# S Curves

## Positive S Curves

Rotating the CURVE knob clockwise from the center steepens the middle of the S curve.

Note: Extreme positive curvature makes the curve almost square just before and after the middle.

## Negative S Curves

Rotating the CURVE knob counterclockwise from the center flattens the middle of the S curve.

Notes:

• Extreme negative curvature makes the curve almost square at both ends.
• Each curve actually starts at the same voltage. But as the curvature becomes more negative, the rise is so fast that the Scope can’t display the initial value.
• With the knob fully counterclockwise, the rise is so fast that the Scope can’t show the initial rise at all.