Touch dynamics
“Touch sensitive” is the highest praise a drive pedal gets, and the vaguest. Underneath the mystique is something measurable: how the circuit’s behavior changes with input level — because your pick attack, your fingers versus a pick, and your guitar’s volume knob are all, to the pedal, just level. Two charts split the question between them: the Compression chart asks “how loud comes out?”, and the Gain Map asks “how dirty, and dirty how?”
Compression: the loudness half
Follow a clean wire and output tracks input decibel for decibel. A clipping circuit can’t: past some level, more input mostly buys more distortion, not more output. The point where the output curve starts giving up is the knee; how flat it goes afterward is how hard the pedal limits.
To your hands, a flat ceiling means your hardest and softest picking come out at nearly the same volume — the evened-out, compressed feel that makes leads easy and dynamics lazy. A gentler slope keeps some of your attack as actual level. Neither is virtue; they’re different instruments.
Cleanup: the character half
The second half of touch is what happens to the recipe as level falls. Roll your guitar’s volume down a third and a pedal that “cleans up” doesn’t just get quieter — it crosses back below its knee, the clipping recedes, and the harmonic content thins toward clean. On the gain map that’s the dark region along the bottom rows; the ~1 % THD contour is effectively the border of “clean on a soft touch”.
A fuzz that stays bright across every row of the map is the opposite animal: always itself, at any picking intensity. Players call one “dynamic” and the other “committed”; the map shows which you’re holding.
Reading a pedal’s touch, quickly
Knee level vs. your signal. A knee near your instrument’s actual output level means the border between clean and driven sits under your fingers — maximum touch response. A knee far below it means you’re always deep in clipping (fuzz territory).
Limiting hardness. The flatter the compression curve past the knee, the more the pedal evens out your dynamics.
Cleanup contour height. On the gain map, how far up the level axis the ~1 % contour sits tells you how much rolling off actually buys.
▶ Lower the drive in Simulation mode and watch the knee meet the signal
For the curious
The compression measurement steps a tone across levels — down to −70 dBFS by default, deep enough to catch high-gain knees — and plots RMS out against RMS in on log-log axes, where a unity-gain wire is a 45° line; knee and post-knee slope come from a two-segment least-squares fit of that curve, so the knee can land between probe levels — and when the curve is compressed across the whole probed range the knee is reported as a bound (“≤”), because the data can only say it lies further down. Steps that come back within 6 dB of the capture’s own noise floor are excluded so hiss can’t masquerade as output level. The gain map repeats the full swept-sine harmonic measurement at stepped amplitudes, so every row is a complete harmonic recipe at one level. “Touch” in this app always means measured input level: the electronics can’t tell a heavy pick from a hot pickup — and that equivalence is exactly what makes the lab result transfer to your hands.