Fractal Audio DRIVE models: Bit Crusher

yek

Contact Fractal for your Custom Title
The contents of this thread, including updates, are available as a PDF Guide. Download it here.

logo-2.png

Bit Crusher


The Bit Crusher model is not an emulation of a run-of-the-mill pedal. Bit crushing is the process of intentionally downgrading audio quality, to create a warmer sound or to use as an effect. So far known, Fractal Audio’s Bit Crusher is not modeled after a specific pedal, although such pedals do exist. A bitcrushing pedal or plugin often has bit reduction and sample rate controls, and more. If you don’t use those controls in the Bit Crusher Drive model, a generic drive remains. Clip Type in the model is set to silicon.

The Axe-Fx II Owner's Manual jokingly describes the Bit Crusher model as follows: "Based on a black box we found lying in the trash outside Studio Harshclip."

Fractal Audio’s Bit Crusher model at default settings showcases the Bit Reduce control. This control appears in all Drive types, so it’s not limited to this Drive model. It intentionally creates nasty digital distortion by reducing the resolution of the signal. Its value is the number of bits that will be subtracted from 24-bit full scale. For example, to create 4-bit audio, set it to “20” (the model's default setting). Note that high values will introduce background hiss and cause the signal to drop out.

Wikipedia:
“Samples in digital audio are recorded as integers or floating-point (real) numbers stored in computer memory. Those numbers are encoded using a series of on and off memory bits. The larger the number of bits, the more accurately a sample encodes the instantaneous volume level of a sampled audio waveform. DAWs today typically use 32-bit floating-point numbers. Early digital audio gear and video games used 8-bit integer samples or less. Roland's classic TR-909 drum machine used 6-bit integer samples. Resolution reduction intentionally reduces the number of bits used for audio samples. As the bit depth goes down, waveforms become more stair-stepped and subtle volume variations are lost. At extreme bit reduction, waveforms are reduced to clicks as a waveform jumps abruptly from low to high and back again without intervening values.”​

Another way to intentionally downgrade signal quality is to use the Sample Rate control which introduces aliasing by reducing the sample rate, from 48kHz all the way to 48Hz. This control also appears in every Drive block.

Wikipedia:
“Digital audio is composed of a rapid series of numeric samples that encode the changing volume of an audio waveform. To accurately represent a smooth waveform, digital audio requires a large number of samples at a high sample rate. The higher the rate, the more accurate the waveform. Higher sample rates also allow higher frequencies to be accurately encoded. DAWs today typically use 44.1 kHz or higher sample rates. Early digital gear used much lower sample rates to conserve memory for stored audio. Sample rate reduction (also called down-sampling) intentionally reduces the sample rate to degrade the quality of the audio. As the sample rate is reduced, waveforms become more coarse and high frequencies are lost. At extreme reductions, the waveform becomes metallic sounding.​

Here’s a popular article about the use of bit depth and sample rate in audio playback

Suggestions:
  • Try the Looper (before or after the Drive block) when experimenting with Bit Reduce and Sample Rate. Record a clip and set it to playback, while adjusting those controls.

  • Attach the Sequencer internal controller to a Synth block and run it through the Bit Crusher.

  • Attach an external controller, like an expression pedal, to the Sample Rate parameter, with adjusted Min and Max modifier settings. Instant dubstep!
Other approaches to creating “lo-fi” sounds:
  • set the Bias control in a Drive block to extreme values
  • lower the sliders in a GEQ block
  • use an IR of a very small speaker cabinet
  • crank the Speaker Drive control in the Amp block
  • use the Ring Modulator block, set to non-tracking
  • apply ample low-pass and high-pass filtering
  • add pink or white noise with the Synth block.
Another thread discussing the Bit Crusher, with clips

Examples of bitcrushing pedals:











Link to the list of published threads
 
Last edited:
I LOVE the unpredictable nature of a bit crusher. It makes things...interesting.

Here's a really extreme example:



And here's something, ah, more musical maybe? The bit crusher is being used on the lead signal but ever so slightly. Listen to the way that last, held note fades out. No studio tricks. That's the bit crusher doing it's delicious thing.

 
I remember going through the drives when I first got my XL and came across this one.. I was like WTF is that some kinda software glitch in the Axe? o_O
 
I find a touch of bit and sample rate reduction really makes a fuzz drive block sound a bit more authentic and helps with that spitting/Velcro fuzz tone
 
Sound very strange, I'm too old :( hahaha
I will try to "Spippolare" (slang Italian) "tweaking".
 
Last edited:
It's not for everyone. I think people, like me, that grew up on late-80s, early-90s industrial electronica will find themselves right at home with it. But if you're after the smooth, elevator jazz tones of a band like the Scorpions, this is not the drive model for you. ;)
lolllllllllllllllllllllllllllllllllllll! Yeah I like the shitty smooth vibe of John Petrucci! To each his own fo sho!
 
Back
Top Bottom