Typical Applications - Aphex COMPELLOR 300 Operating Manual

audio through a tuneable high pass filter. The shape of this filter is also
variable, via the PEAKING control, from a fairly gentle slope to a steeper one
with a slight peak. The filter removes unneeded low frequency material and
creates the necessary frequency-dependent phase shift.
The filter output is then fed to the next stage, the harmonics generator, via
the DRIVE control. This is where the musically-related harmonics are gener-
ated and mixed with high-passed information. This complex material then
goes through the MIX pot, where a small portion ( typically 20 dB below) is
added to the main signal. Although this amount of information is so small, it
shouldn't even be heard, you will perceive a significant increase in mid- and
high- frequency energy.
2.2 Typical Applications
The COMPELLOR is a useful tool for virtually any audio system. It's hard
even to imagine a situation where the sound system could not benefit from a
more controlled dynamic range with total peak protection.
There has been so much attention brought to the newest increases in dy-
namic range with the onset of digital technology that some of us may have
lost sight of the difference between maximum dynamic range and usable
dynamic range.
In the typical live sound application, for example, there is in reality
a very small difference between the maximum level available from the sound
system (or the threshold of pain), and the ambient noise level in a club,
concert hall or the like. The 80 or 90 dB of dynamic range so sought after is
completely useless in such instances. It is also useless if it cannot be trans-
ferred from a compact disc to a cassette. Without a COMPELLOR in the
audio chain, you have to decide between losing quiet signals into the noise or
having distortion from overload on loud sounds.
Your ear actually prefers listening to reduced dynamic range material, as long
as open, transient qualities are maintained. The COMPELLOR is designed to
accomplish these goals, while remaining quite invisible in the process.
The following typical applications are brief examples of how any one of the
COMPELLOR models (300, 301, 303) can be used to improve sound quality
within your own audio discipline.
2.2.1 Broadcast Pre-Processing
Most other processors have a "sweet spot" in which they work best, usually
with minimum amounts of gain reduction. The COMPELLOR will drive the
audio consistently into that spot, making a station practically "jock proof."
By taking the burden of heavy gain reduction off following devices (espe-
cially limiters) the devices can do what they do best, with minimum negative
effect on the audio quality.
2-8 Operational Characteristics