Ashly LIMITER/COMPRESSORS CL-100 - Manual (Page 11)

Two important features emerged from this research:
1. We designed the detector to let the attack and release times speed
up as more and more limiting occurs. The compression ratio also
increases. This lets us maintain peaks fairly close to a constant
ceiling level, but allows the illusion of increasing loudness as
input level increases, thereby preventing complete loss of dynamics
when limiting.
2. We incorporated a double release time constant. When release time
was set slow with a single time constant, transients such as mic
“pops” and record scratches caused a quick reduction in gain and
a slow fade-up, making the action of the limiter very obvious.
With the double time constant, release from gain reduction after
a brief transient is always fast, with a slower release after a
sustained overdrive.
When choosing a compressor/limiter, you can see that it is veiy
important to listen to it in your particular application and see that it sounds
the way you want. There are lots of these devices with seemingly excellent
specs which sound very different with real program material applied to them.
Peak Or RMS
There are several ways oflooking at a signal to determine its level. A
peak detector looks at the maximum voltage a signal reaches regardless of
its’ waveform, while an RMS (root mean square) detector looks at the energy
in a signal regardless of the short term voltage levels. This makes a peak
detector the correct choice for preventing clipping, overmodulation, or tape
saturation, while an RMS detector can be used to restrict material to a given
loudness. When an RMS limiter is used to prevent clipping, the result is
unpredictable. For instance, a flute and a snare drum which are limited to
the same RMS level might have peak levels as much as 30 dB apart! Use
peak limiters to prevent clipping. □
T8 ASHLY
APPLICATIOHS
The applications of the Ashly CL-SERIES Compressor/Limiters can be
divided into two basic categories; it may be used as a protective device to
prevent audio levels finom overloading associated systems, such as tape
recorders, amplifiers, speakers, or transmitters, or it may be used to create
special effects and unusual sounds for recording and musical performance.
These two different approaches to using the compressor/liiniter impose vastly
different and contradictory demands on the unit’s performance.
When used in a protective mode, the unit is usually required to control
the dynamic range of an incoming signal, and to do so without audible side
effects. The listener should be unaware of the limiter’s presence.
In the early 1960’s, when musicians began looking at the recording
process as a way to create new sounds, the pumping effect which had been
avoided like the plague by earlier engineers was suddenly seized upon and
utilized as a creative tool laying the groundwork for many of the sounds
which are now considered indispensable in contemporary music. In this
role, the compressor is used because you can hear it working, and control
of dynamic range is only a secondary consideration. The Ashly CL models,
with their wide range of control parameters, are well suited to both of
these applications.
The Compressor/Limiter As A Protective Device
The CLrSERIES provides fast and accurate gain control for the
prevention of sound system overload due to unexpected transients. Sound
system distortion is usually a result of amplifiers running out of power, in
which case nice round waveforms turn into harsh-sounding squared-off
waveforms. Looking at it fixjm the perspective of a speaker diaphragm, this
means that, whereas in normal operation the diaphragm is required to
accelerate, slow down, smoothly change direction, and accelerate again,
distorted operation requires an instant acceleration, instant stop, a change of
direction, and instant acceleration again.
ABHLY 19