Solidyne 542 APC, Owner'S Manual

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For music with vocal predominance and for micro-
phones, the MB-AGC correction range should be narrow,
about 2dB, except for the low band which can manage
differences of 3 to 4dB (suitable values for balancing
voices and materials with different bass levels).
4.5.3 Attack, release and hold
Each band has its Attack, Release and Hold times.
These times interact with wideband AGC times.
The controls of time works over the band selected in
the buttons located at right.
In general, the MB-AGC attack and recovery times are
adjusted to work faster than the times used in the WB-
AGC. The WB-AGC makes global level corrections, while
the MB-AGC works on more abrupt level variations
within a range of frequencies.
4.6 Dynamic compression
The reduction of dynamics is produced by the combina-
tion of three stages: compression; limiting and clipping.
They work in a complementary way to reduce signal dy-
namics and increase average energy. The higher the ac-
tion of these stages, the more "dense" and "compact" is
the sound. The adjustment of these three stages must be
done together.
Broadly speaking:
•
The compressor works with gentle compression
slopes and low thresholds. This reduces the dy-
namics of the signal over a wide range of levels.
•
The limiter works with very steep slopes. The lim-
iter works with higher threshold levels, but applies
a large gain reduction and the signals never go
above the threshold. It drastically reduces the dy-
namic range but its action can be very audible
(depending on the settings of other stages).
•
Attack times are usually slower on the compres-
sor, and very fast on the limiter. This allows the
attacks of the sound that pass through the com-
pressor to be preserved, and only the highest level
peaks are attenuated by the limiter. All attacks
that fall below the threshold of the limiter pass
(depends on the DRIVE setting of the limiter)
adding naturalness to the sound.
4.6.1 MULTI-BAND COMPRESSOR
The 5 working bands are those established in the multi-
band AGC. Each compressor is independent and has the
following settings:
Thershold (THS)
The threshold value changes the level at which the com-
pressor starts to work. As soon as the signal reaches the
threshold, attack time comes into play and then attenua-
tion based on the compression ratio.
Lowering the threshold increases the compression, but de-
creases the energy in the band, as the compressor attenu-
ates more signal peaks. To compensate the attenuation
caused by the increase in compression, the level of that
band must be raised in the Drive control of Limiter or using
the Density Equalizer.
RATIO
The compression ratio defines the applied attenuation.
The compressors work with a smooth transition (soft
knee). As a general rule of thumb, the lower the threshold
level, the lower the compression ratio, and vice versa. A
low threshold and a smooth compression ratio will affect
the dynamics of more signals, which is necessary to
achieve a dense and very compact sound in combination
with the limiter.
Attack times (ATK)
It is the time it takes for the band compressor to act, after
the signal exceeds the threshold. Slow attack times gener-
ate more "impact" and presence in that band (especially in
the low bands) but will be greater the action of the bnd lim-
iter and the soft clipers. This is because the sound attack
"passes" through the compressor, and reaches the limiter
with a high level.
Attack times are set for each band. The characteristics of
the material to be processed again come into play. In gen-
eral terms, some musical styles such as rock and pop, tol-
erate more clipping, ie slower attack times. This provides a
great sense of dynamic range (sound depth and impact of
percussion). To achieve more punch in the percussion, it is
advisable to use slower attack times on the LOW and M1
bands. For orchestral, jazz, piano, it is convenient to use
fast attack times.
Release times
It is the time it takes the compressor to return to a 1:1 ra-
tio (linear) after the signal falls below the threshold.
Release times are also key adjustments to optimize the
dynamic range feel. In general terms; if the release time is
slow the compressor acts practically at all times; attenuat-
ing the level of the band. The attacks have less incidence,
because they are attenuated during the release time. With
very slow release times the compressor acts in a similar
way to a leveler, maintaining the dynamics but without
generating a great increase of loudness.
For example: electronic music requires fast release time in
the low band, to reinforce the punch of techno drum. The
compressor must release so that each beat is affected by
the attack time.
Audio Processing Core - SOLIDYNE 542 APC Page 35