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Multiband Compressor [MBC]
5.19
The Axe-Fx II contains a three-band compressor that is great for mastering or compressing a mix. It also works as a
tone-shaping tool, providing independent level and dynamics control over low, mid, and high frequencies.
The basic principle of the
Multiband Compressor
is that the input is divided into three component signals using a
crossover. Compression is applied to the bands individually before they are recombined. The MBC lets you isolate
frequency bands of the input material and apply different types or amounts of compression to each. Multiband
compression is a de-facto mastering tool and can greatly
improve a final mix or a complex guitar sound.
Each Axe-Fx II preset can use two fully independent
Multiband Compressor
blocks.
Parameters
FREQ1
– Sets the crossover frequency between
bands 1 and 2 from 50–500 Hz.
FREQ2
– Sets the crossover frequency between
bands 2 and 3 from 1000–10000 Hz.
Each compressor section has its own menu page with
the following parameters:
THRSH
– Sets the threshold above which output
compression starts to occur.
RATIO
– Sets the input-to-output ratio for signals
above the THRESHOLD. A ratio of 2.00 (2:1) means
an increase of 2 dB is needed at the input to produce an increase of 1 dB at the output.
ATT
– Attack rate. Sets how long it takes for compression to occur once the signal exceeds the threshold.
Slower values allow more of the loud signal to punch through before the compressor can reduce it.
REL
– Release rate. Sets how long it takes for the level to return to normal after the signal falls beneath the
threshold. Slower times can cause the compressor’s gain reduction to remain in effect even after a loud signal
has given way to a quieter section.
LEVEL
– Sets the output level of the selected band.
DET
– Selects whether the compressors will use RMS (“Root Mean Square”), FAST RMS (mimicking classic
rack-mount compressors), PEAK detection, or RMS+PEAK detection. RMS is “smooth” and useful to even out
program material over longer periods of time. Peak detection, commonly used with guitar, is useful for fast
limiting. RMS+Peak responds quickly to transients but also considers RMS for overall smoothness.
MUTE
– Mutes the output of the band. By muting two bands, you can solo the third. By muting one band,
you can focus on its contribution to the overall mix.
Figure 5-17 – Stylized view of the Multiband Compressor
