Apple Logic Express 7 - Manual (Page 40)

40 Chapter 5 Distortion
Bitcrusher
Bitcrusher is the ultimate digital distortion box. You can do all kinds of wild stuff with it,
such as recreate the 8-bit sound of the pioneering days of digital audio, create artificial
aliasing by dividing the sample rate, or distort signals so radically that they are
rendered unrecognizable.
Warning: The Bitcrusher can damage your hearing (and speakers) when operated at
high volumes.
The Drive slider boosts the level at the input of the Bitcrusher. Please note that this
tends to excite the clipping stage located at the output of the Bitcrusher as well.
The Resolution knob allows you to reduce the resolution from 24 bits down to 1 bit.
The number of bits is always an exponent of two. The range of available values is
equivalent to the exponents of two that a given sample rate can handle. As an
example, 65,536 different values are possible for 16 bits, whereas at 8 bits, you’re left
with just 256. The sonic image becomes ever more ragged as the values decrease
because the number of sampling errors increases, thus generating more distortion. At
extremely low bit resolutions, the amount of distortion can be greater than the level of
the usable signal.
The Downsampling slider lowers the sample rate. As an example, at a value of 2
(halved), the original 44.1 kHz signal is sampled at a rate of just 22.05 kHz. At a factor of
10, the rate is knocked all the way down to 4.41 kHz.
The Clip Level slider lets you define the point below the normal threshold that you want
the signal to start clipping. The Mode buttons are used to determine whether the signal
peaks that exceed the clip level are Folded, Cut, or Displaced (check out the graphics
on the buttons and the resulting waveform in the display). The kind of clipping that
occurs in standard digital systems is usually closest to that of the center mode (Cut).
Internal distortion may generate clipping similar to the types generated by the other
two modes.