Ashly Compressor/Limiter CL-52 - Manual

Compressor/Limiters
model CL-50E
model CL-52E
Five-Year Worry-
Free Warranty
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CL-52E
A
I shly's Compressor/Limiters are
used to place a ceiling on the
peak levels of program materi­
al. When peaks exceed this
ceiling, gain is reduced to keep
peaks \«ithin specified limits.
I
The amount of gain reduction,
attack and release times, and the output
gain matching are all precise and inde­
pendent adjustments. This makes the CL-
50E and the CL-52E extremely useful for
such diverse applications as loudspeaker
protection, broadcast limiting or compres­
sion, recording, tape-to-disc transfer, spe­
cial effects, vocal level control, and
musical instrument sustain.
The two important components of any
limiter are the VGA (Voltage Controlled
Amplifier), which actually performs the
function of reducing gain, and the detec­
tor, which essentially tells the VGA what to
do. i.e. when to reduce reduce the gain
and by how much. On the surface, it might
seem like the VGA is the most critical
component, since audio actually passes
through it while the detector merely pro­
vides it with a DC control voltage, but
experience has shown us that both are
crucial to the overall sound.
The VGA in Ashly’s Compressor/
Limiters represents a new generation of
integrated circuits that offer exceptionally
low noise and distortion figures, flat fre­
quency response, freedom from thermal
drift and excellent reliability. Audio signals
passing through the VGA emerge clean
and uncolored.
The detector has the task of monitoring
incoming audio levels and changing the
gain of the VGA as determined by the set­
tings of the front panel controls. The
detector in Ashly's Compressor/Limiters is
a fully symmetrical peak responding type,
and includes a ’send-return' loop which
allows frequency selective limiting and
other effects.
The detector must constantly adjust the
gain of the audio path in a manner which
keeps the level under control while still
sounding acceptable to the listener. This
constantly changing gain is a dynamic
action, while conventional audio measure­
ments like noise and distortion checks are
static (constant level). This led us to use a
purely subjective approach in the design
of the detector; we did a lot of listening to
determine what sounded good and what
didn't. As a result of this research, we
designed the detector to allow the attack
and release times to speed up as more
and more limiting occurs (the compression
ratio also increases), and we utilized a
double-release time constant to minimize
'pumping' and 'breathing'. The result is a
natural-sounding compressor/limiter that
responds very well to a wide variety of
audio applications.
The CL-50E is Ashly's single channel
compressor/limiter. The CL-52E is essen­
tially two CL-50E's in one rack space, but
it offers improved metering and switching.
The CL-52E can be used as a stereo
compressor/limiter or as two separate
mono units. Ten-level meters are provided
on each channel to indicate gain-reduc­
tion and output level.
The CL-50E and CL-52E compressor/
limiters, like all Ashly products, are now
fully covered by Ashly's exclusive five-
year worry-free warranty.
Extremely Low Noise
and Distortion
Detector Patch Points
for Frequency-Selective
Limiting
Gain Reduction Meters
In-Out Bypass
Switching
Inputs and Outputs May
Be Used Balanced or
Unbalanced
Unusually Wide
Control Range on Ail
Parameters
Output Level Meters
and Clipping Indicators
(CL-52E)
Front Panel Stereo
Tie Switch (CL-52E)