Effect 6 of 15 · Pedals

Overdrive: soft clipping, oversampled

Gain into a smooth S-shaped curve. Quiet signals pass nearly unchanged; loud ones have their peaks rounded off, the same on both sides.

Play it alone All fifteen effects The whole board

Play it alone

Signal into the board

The test signals are synthesized by this page, sample by sample. Your instrument is asked for only when you press Start with “Your instrument” chosen, with the browser’s echo cancellation, noise suppression and automatic gain control switched off.

Output volume70%

Output levelsilent

Sample rate: not started
Processing latency: not started
Output latency: not started
Input latency: not started
Reported total: not started

Browser audio has latency: you hear each note a little after you play it. These are the browser’s own figures and they leave things out.

What the latency figures mean

The overdrive, alone

In, this one pedal, out. Drag a knob sideways, or focus it and use the arrow keys or the wheel. The whole board has the rest.

Overdrive
Drive+18 dB
Tone2.4 kHz
Level−9 dB

The signal

What it does to the signal

Overdrive is clipping: the signal is made larger than the stage that follows can carry, and the tops and bottoms of the wave are flattened. The flattening adds harmonics, and it squeezes the difference between loud and quiet.

Here the signal first passes a 12 dB-per-octave high-pass at 140 Hz, so that the low strings do not take over the clipping. Drive is gain. The curve is the hyperbolic tangent of four times its input: a straight line through the middle that bends over smoothly and levels off at full scale, identical above and below zero. Its slope at the centre is 4, so the gain in front of it is set 12 dB lower than the knob reads; at Drive 0 dB a quiet signal leaves at the level it arrived.

Clipping creates harmonics far above the note, and in a digital system any of them above half the sample rate fold back down as tones unrelated to it. So the curve is applied at four times the sample rate: the Web Audio specification describes the node’s 4x mode as up-sampling the input, applying the curve and down-sampling the result. After the curve come a 12 dB-per-octave low-pass, which is the Tone knob, and the output level.

General definition: Wikipedia, “Distortion (music)” (revision 1351139491, read 2026-09-28). Everything on this page about how this pedal works describes this page’s own code. It is built from standard Web Audio nodes.

The graph

The graph, drawn.

audiocontrol: moves a setting, is never heard

Six nodes in a row, every one of them a standard Web Audio node.

The knobs

Every knob, in real units.

Knob	Range	Starts at	What it changes
Drive	0 dB to +40 dB	+18 dB	Gain before the curve. The curve is close to a straight line for small signals, so at 0 dB a quiet signal leaves at about the level it arrived.
Tone	700 Hz to 7 kHz	2.4 kHz	The corner of a 12 dB-per-octave low-pass filter after the curve.
Level	−40 dB to +12 dB	−9 dB	Output gain. It starts below 0 dB because a clipped wave is a much louder thing than the note that went in.

Measured

What the test measured

Rendered offline, then measured

Switched off and rendered over 48,000 samples of the plucked-string signal, the output was identical to the input in every sample, and the pedal was not in the graph. [as described]
Drive 0 dB, a 440 Hz tone at −34 dBFS: it came out 0.00 dB from where it went in, with harmonics 2 to 5 adding up to 0.00% of the fundamental. [as described]
Drive +30 dB, a 220 Hz tone at −12 dBFS: the third harmonic (660 Hz) came out −10.1 dB relative to the fundamental and the fifth −15.5 dB, while the second (440 Hz) was at −164.7 dB. A symmetrical curve makes odd harmonics. [as described]
With Level at 0 dB the output peaked at 0.0 dBFS: the curve flattens at full scale however hard it is driven. [as described]
The ninth harmonic (1,980 Hz) was 18.2 dB stronger with Tone at 7 kHz than with Tone at 700 Hz. [as described]

Rendered in an OfflineAudioContext at 48,000 Hz in Chrome/154.0.8037.58, 2026-09-29 01:07 UTC. The test is work the page’s builder ran, not something your browser does when you open this page.

Limits

The curve is fixed and has no memory: the output at any instant depends only on the input at that instant. Real circuits are not like that, and this does not model one.
Oversampling adds a little delay. The Web Audio specification notes that it does and that the amount varies from one browser to another.
It is symmetrical, so it makes odd harmonics and almost no even ones. The fuzz is the lopsided one.

Where it goes in the chain

Early, after the wah and the compressor. GuitarPlayer’s guide to pedal order says overdrive “should come early in your chain”, and notes that players stack drives in both orders. The whole order, and the reasons, are on the signal chain page.

← Compressor Fuzz →

Method

What is computed, and what is read.

Computed here, nothing fetched

Every sound on these pages is computed in your browser by the Web Audio API: 9 of the 15 pedals are graphs of the engine’s standard nodes, 5 are AudioWorklet processors, the wah is both, and the 3 test signals are synthesized sample by sample. No recording is loaded and no data feed is read. The one request the board’s own scripts make is for their AudioWorklet module, a file on labs.llc; the pitch detector is the one the Tuner uses.

Every effect was rendered offline with a known signal and measured: 73 of 73 checks came out as described. Nothing was tested on a real instrument or audio interface, only one browser was used, and nobody listened: the tests measure numbers, not tone. The method, the table of checks and what the latency figures mean are on the about page.

Sources

The W3C Web Audio API 1.1 and Media Capture and Streams specifications (W3C Document License); RFC 9110 and RFC 3986 for the share link’s fragment; GuitarPlayer’s guide to pedal order, quoted briefly; Wikibooks, “Guitar/Effects Pedals”; and each effect’s English Wikipedia article at a named revision (CC BY-SA). All read 2026-09-28; none is fetched by the page.

What happens to what you play

Audio from your input goes into the audio graph and out to your output device, and nowhere else: it is not recorded, stored or sent. Presets and the board as you left it stay in this browser’s local storage. A share link carries the board after the #, which browsers do not send to servers.