Apple Logic Express 7 - Manual (Page 41)

Chapter 5 Distortion 41
Clip Distortion
The Clip Distortion plug-in is a non-linear distortion effect that produces unpredictable
spectra. Beyond drastic distortions, it’s well suited for the simulation of warm tube
overdrive sounds.
The best way to learn what effect the various parameters have is to experiment with
them on different signal sources. As a starting point, the following describes what each
control basically does:
The signal is first amplified by the Drive value, which is a simple gain control. The signal
then passes through a highpass filter. The filter’s cutoff frequency is determined by the
Tone control. The actual non-linear distortion process is controlled by the Symmetry
parameter.
Once the signal has been distorted asymmetrically, the signal passes through a lowpass
filter. This filter’s cutoff frequency is determined by the Filter fader. The Mix parameter
combines the effected signal with the dry signal. This mixed signal then passes through
yet another lowpass filter, where the cutoff frequency is controlled by the Sum Filter
parameter. All filters have a slope of 6 dB/Oct.
The last stage of signal processing is a tunable shelving filter. If you set its Frequency to
about 12 kHz, it will behave like a normal treble control, as found in any mixer’s channel
strip or stereo hi-fi amplifier. Unlike such treble controls, this filter allows for boosts or
cuts of up to ±30 dB (Gain parameter). This somewhat unorthodox combination of
serially connected filters allows for gaps in the frequency spectra that can sound quite
good with this sort of non-linear distortion. The clip circuit graphic visually depicts
every parameter, with the exception of the shelving filter controls.
If you activate the 001/011 button, you have access to two more parameters: Input Gain
and Output Gain. These can be used to raise/lower the input and output signal levels
by up to 30 dB.