Bitcrusher Online

How the Distortion And Bitcrusher works

Most audio tools try to make sound cleaner. This one makes it worse on purpose, and that is a legitimate creative decision with a long history. Guitar distortion started as a torn speaker cone and a faulty mixing desk in the early 1960s and became the sound of rock. The gritty 12-bit drums of hip-hop came from the limits of the E-mu SP-1200 and Akai MPC60 samplers. Chiptune is the sound of 8-bit game consoles. The three effects here, distortion, bit reduction and sample-rate hold, each recreate one of those limits, and they can be combined.

How the distortion and bitcrusher online effects work

Every sample passes through three stages in order: distortion first, then bit reduction, then sample hold. That is the order that sounds most like real hardware being pushed too hard. The Mix control then blends the result with the untouched original.

Distortion. The signal is amplified by the drive, where every 6 dB roughly doubles it, and then passed through a shaping curve that stops it exceeding full scale. The shape of that curve decides the character:

• Soft clip uses a hyperbolic tangent, rounding the peaks gradually. It adds mostly odd harmonics at low level and resembles an overdriven valve amplifier or tape machine: warm at 6 dB, singing at 12 to 18 dB.
• Hard clip chops peaks off flat at full scale, like a transistor fuzz pedal or a digital overload. It adds strong high harmonics and sounds harsher and buzzier.
• Fuzz uses an exponential curve that squashes the signal quickly, so even quiet material sounds saturated and sustains longer, much like a vintage fuzz box.
• Fold-back uses a sine curve, so a signal pushed past the peak folds back down instead of flattening. The result is metallic and inharmonic, like no analogue device, and suits industrial, glitch and synth sound design.

Bit depth. Each sample is rounded to the nearest of a limited set of levels: 65,536 at 16 bits, 4,096 at 12, 256 at 8, 16 at 4 and 4 at 2. Each bit removed raises the noise floor by about 6 dB. At 16 bits nothing audible changes. At 12 a grain appears in quiet passages and reverb tails, which is the SP-1200 sound. At 8 it is early samplers, the Amiga and game consoles. At 4 the music is buried in noise, and at 2 it is a square-wave buzz. Unlike the bit depth converter, no dither is added, because the crunch is the point.

Sample-rate hold. Only every Nth sample is kept and the ones in between repeat it. This is what a genuinely low sample rate sounds like without the anti-alias filter that would make it polite. Frequencies above half the effective rate fold back down as aliasing, a metallic sparkle that does not follow the pitch of the music. Holding 4 samples on a 44.1 kHz file gives an effective 11 kHz; holding 16 gives about 2.8 kHz, a phone line heard through a tin can.

How to read the result

• Source shows the channel count, sample rate and length of your file.
• Distortion confirms the curve and drive in dB. 0 dB still passes the signal through the curve, which only affects the loudest peaks.
• Bit depth shows the setting, with "no crush" at 16 bits and "quantisation noise audible" below that.
• Sample rate shows "full" when nothing is held, otherwise the hold count and the effective rate in Hz. Compare it with the source rate to see how much bandwidth is left: anything above half the effective rate is aliasing.
• Mix is the percentage of processed signal in the output.

Where each effect is used

• Drums. Bit crushing to 10 or 12 bits with a hold of 2 gives drum loops the character of classic hip-hop samplers. Soft clip at 6 to 9 dB adds punch to a snare.
• Bass. Soft or fuzz distortion adds upper harmonics that let a bass line be heard on phone and laptop speakers, which cannot reproduce the fundamental.
• Vocals. Hard clip at low mix gives an aggressive, radio-edge vocal; heavy sample hold gives a robotic, lo-fi telephone voice.
• Synths and sound design. Fold-back and extreme bit depth create textures for game audio, glitch music and sci-fi effects.
• Lo-fi and chiptune. 8 bits and a hold of 4 to 8 turn any melody into something that sounds like it came from a cartridge.

Tips and pitfalls

• Use parallel processing. Set Mix to 20–30 % to tuck a heavily crushed copy under the clean signal. You keep the attack and definition of the original and gain the grit. This is standard practice on drum buses.
• Loudness fools the ear. Distortion makes things louder and denser, and louder almost always sounds better at first. Compare at matched levels before deciding.
• Watch the output level. Every curve limits the peaks to full scale, but a 100 % wet signal is much denser than the original. Run the result through the audio normalizer if it needs to sit with other tracks.
• Tame the fizz. Hard clip, fold-back and heavy sample hold create harsh high frequencies. Cut above 8–10 kHz afterwards with the equalizer for a warmer result.
• Start subtle. Extreme settings are fun for a few seconds but tiring over a whole track. Most mixes use these effects at a level you feel rather than hear.
• Distortion is not reversible. Keep the original file; clipped peaks and discarded bits cannot be recovered.

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