Compare

How different are they, really? Informal A/B comparison mostly measures volume — louder reads as better down to fractions of a decibel. The Compare view puts two measured Harmonic Distortion recipes on the same axes, quantifies their gap, and lets you hear them through their measured models at matched loudness. It compares Compression the same way: two touch-response curves on one shared axis pair. Select two records of the same kind in the library (⌘-click), or use the Compare button on any Harmonic Distortion or Compression record.

The distance number

The distance is the average gap between the two devices’ harmonic levels, in dB, pooled over every harmonic and every audible note in the band both measurements cover — cells past either measurement’s reliable band edge are skipped, so analysis artifacts never inflate the number. Zero means identical recipes; around 1 dB is a subtle knob nudge; a few dB is clearly different settings; tens of dB is a different circuit. The per-harmonic bars say where the difference lives — even orders mean the devices differ in asymmetry (warmth), odd orders mean different clipping hardness (grit). What it does not measure: loudness, noise, feel, or anything time-variant — two devices can be 0 dB apart here and still differ in sag or hum.

Use it for repeatability too: re-measure the same pedal on another day and the distance tells you how trustworthy small differences are. Anything below your own re-patch repeatability is measurement weather, not tone.

The overlay

A solid blue and a dashed orange curve on shared axes — THD or any harmonic the two measurements share — with the gap between them shaded. Wide shading at low notes and none at high notes is a bass-response difference; a uniform vertical offset on one harmonic is a level difference in that family. Where a curve turns faint and finely dashed it has passed its measurement’s reliable band edge — those tails are artifacts, drawn unshaded and never counted. Check the drive chips first: measurements made at different drive levels differ for that reason alone.

Hearing the difference

One plucked note rendered through both records’ measured Hammerstein models, loudness-matched to the same target, toggleable A/B on a shared clock. Because neither side can win by being louder, what survives the toggle is real character: harmonic recipe, clipping hardness, tone shaping. The Blind test button turns the panel into an A/B/X trial — the honest way to find out whether you can actually hear the difference. The audition is illustrative — a model from one sweep, not an emulation product — but it is an honest one.

The blind test (A/B/X)

Knowing which pedal is playing changes what you hear — expectation bias is as real as loudness bias. The Blind test (A/B/X) button runs the classic honest protocol: a third lane, X, secretly plays either A or B on the same sample-locked clock. Flip freely between A, B, and X, then call it — the panel reveals the answer and keeps a running tally.

Read the tally the way listening researchers do: a long run of correct calls means the difference is genuinely audible to you, on your playback chain (see Listening conditions); hovering around half is the polite way of learning that it isn’t. Eight of ten is a common bar. Both outcomes are useful — one tells you the two settings matter, the other frees you from paying for a difference you can’t hear.

Comparing compression

Select two Compression records instead and Compare overlays their touch-response curves and distortion-vs-level traces.

Both touch-response curves are drawn on ONE shared axis pair — the same span of input and output levels. The solo Compression view scales its axes to fit each record, which is right for reading one curve but sabotages side-by-side judgment: a limiter whose entire output moves 8 dB can look as structured as a clean boost until you read the numbers. On shared axes, flat is flat and low is quiet. Knee and cleanup markers are drawn for both records in their A/B colors; a knee marked “≤” is a bound, not a reading — that curve is already compressing at the quietest level measured, so the true knee lies at or below the line and the gap to the other record’s knee cannot be quantified from these measurements.

The same two records’ THD-vs-level traces on a shared log axis: how dirt builds as you dig in, side by side. Where one trace crosses the 1% rule and the other doesn’t, one device has a clean floor and the other never cleans up. A trace that hugs a high THD value across the whole level span is a fuzz-style always-on distortion; one that climbs through the span is drive that responds to touch.

If the two records were measured at different probe notes the view says so: level behavior still compares, but tone-dependent differences (a bass-heavy fuzz probed at E2 vs A3) ride along with the level story.

Pivot: compare a whole control at once

After a family run, its sweep node’s overview page offers Open pivot comparison (the coverage matrix has the same entry): choose one switch — say a 7-way clipping-diode selector — and every measured position appears overlaid on one chart (or as small multiples), each line carrying its canonical label like TS [Ge/Ge · Drive noon]. One control varies, everything else held: the factorial evening becomes a textbook figure.

Common misreadings

• Distance is not “betterness”. It’s a difference meter, not a score. A 12 dB distance says the two will sound clearly different, not which one you’ll like.

• Matched drive matters. Comparing a Harmonic Distortion record measured at −36 dBFS against one at −12 dBFS mostly measures the gain map of one device, not the difference between two. Measure both at the same drive first.

• The audition inherits each measurement’s limits. Time-variant behavior (sag, bias drift) isn’t in a Hammerstein model, so two devices that differ mainly in feel can audition more alike than they play.

Try it: select two records of the same kind — Harmonic Distortion or Compression — in the library with ⌘-click.