Voltage Controlled Amplifier (Vca); Inputs - Alto ACL4 User Manual

So the operating level must be as high as possible but not high enough to generate distortion.
There is a very easy way to obtain this. With the volume knob in hand you can increase the volume during low
passages and decrease the volume during loud passages. Unfortunately even the Great Houdini would not
be fast enough to monitor carefully the speed of the musical signal and it would be impossible to detect sig-
nal peaks and consequently levelling them out. Manual control is therefore out of question. The answer is
AGC (automatic gain control); a device that will monitor the signal in real time and that will adjust the gain
for the best S/N ratio without producing distortion. So, the name of this device is "Compressor/limiter".
2.1.3 More technical stuff about Compressor/Limiters
Try to measure the dynamic range of musical instruments. You will find out that your can ear will handle
range during which the distortion and overloading will be generated in your audio equipment.
To avoid these, compressor/ Limiters will be used. Both Compressors and Limiters more or less do the same
job but Limiters brutally limit the audio signal above a set threshold, while Compressors handle signal in a
much more civilised way and over a wide range of levels. If an audio signal exceed the threshold set by the
User the limiter will kill any audio signal above that threshold. Period! Also Compressors perform their function
when the audio signal exceed a certain threshold but the signal is not killed brutally. The audio signal will be
reduced in gain in proportion with the amount above the set threshold.

2.2 Voltage Controlled Amplifier (VCA)

The VCA is the soul of the ACL4 and it is one of the best components available today in his category thanks to
its excellent performances in terms of distortion, linearity, noise and temperature stability.

2.3 Inputs

2.3.1 Take it easy: Balanced Inputs
To make your life easy and clean we have provided ACL4 with electronically balanced inputs. Even if you
operate at high signal levels, hum and noise will be reduce automatically. There is also a servo-function that
will automatically adjust the internal level when unbalanced connectors are detected. The correction if of
6dB and it will avoid differences in level in between input and output signal.
Chart. 1 The dynamic range capabilities of various devices
Clipping Aera Clipping Signal heavily distrorted Clipping Signal heavily distrorted
Noise Aera Low level signal drowned out by noise Low level signal drowned out by noise
Chart. 2 The interactive relationship between the operating level and the headroom
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