SPL compressor technology
In the compressor/limiter section of the Channel One the parameters for the time constants
(attack and release) are set automatically and adapt themselves to the changing conditions
of the input signal, far better than can ever be achieved by manual adjustments. The transient
and final oscillation behavior of voices and instruments are constantly changing and at times
are so erratic that a manual control will only achieve good average values, which at critical
moments can produce disadvantageous effects (e. g. distorted sounds, “pumping”, etc).
If for example the compressor has to react very quickly to harsh P or T noises it must also
be capable of reacting slowly to softer tones – otherwise distortion occurs. Accordingly the
Channel One compressor regulates the level of large fluctuations faster than smaller ones;
tones of longer duration are automatically processed with a longer attack time to prevent
distortions.
The automatic setting of the release times is dependent on the input signal, too. Fast and
large level fluctuations are correspondingly processed with shorter time constants than
minor fluctuations in order to limit the distortion of the audio signal as far as possible. Overall
this technique provides the optimal solution between fast, unobtrusive control response and
the least distortion of the audio signal. The result is a natural and transparent sound impres-
sion.
A further technical specialty of the circuitry contributes to the high audio quality of the
compressor in the Channel One: SPL’s double VCA drive. One VCA receives the in-phase,
the other the out-of-phase signal. Subsequently the signal is passed through a differential
amplifier. The effect of this circuitry is that distortion products and offset fluctuations can be
removed – the product of the differential of both signals means that possible interference is
canceled out. The original information is however further amplified by 6 dB. In addition the
VCAs provide relief to each other because they share their loads. They do not even run the
danger of operating in the saturation range, which ensures to avoid offset noises, audible as
clicks or pops.
SPL’s double VCA drive circuitry overall displays vastly improved distortion values so that a
distinctly clearer and more transparent sound impression is achieved than with conventional
circuitry. Voices and instruments are given a considerably more natural and dynamic timbre
whereas ”muffled” tones are not audible.
The compressor characteristics are portrayed on page 26.
16
Channel One
Compressor
Control Elements
Содержание Channel One 2950
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Страница 30: ...Manual Channel One Model 2950...