5 - Effects
Core Effects Descriptions
E-MU PCIe Digital Audio Systems
91
RFX Compressor
The RFX Compressor is a full-featured stereo compressor effect which features the
standard parameters available on most compressors as well as a collection of
additional advanced parameters that are useful for more sophisticated applications and
special effects:
• Threshold, Ratio, Attack and Release w/gain metering
• Auto-makeup gain
• Adjustable soft knee
• Adjustable lookahead/delay
• Noise gate (downward expander)
• Compressor “tail” expansion
• Program-dependent release
• Negative compression ratios
Signal Flow
The block diagram of the RFX Compressor is shown below.
I
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L
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R
O
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L
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O
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Co
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esso
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Look
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ad
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100
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Co
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esso
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Del
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Att
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A
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to Rele
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Rele
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Soft
K
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M
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x.
Co
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p.
Neg.
Co
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Co
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Del
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0
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50
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S
Level
Detecto
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Co
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Th
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G
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(& S
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)
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Mo
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Gai
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Cells
SIGNAL PATH
SIDECHAIN
Note that the effect is split between a signal path and a sidechain path that contains the
compressor's level detectors and gain computation. The signal path of the RFX
Compressor is very close to a “straight wire”, with only a delay line and one gain
control element inserted in it. The sidechain contains the bulk of the compressor
algorithm and is responsible for computing the gain control signal. Signal multiplexers
at the front of the signal path and sidechain allow linked stereo compression or split
signal path/sidechain processing.
The RFX Compressor does not have the input gain control that is found on some
compressors. These are typically used to align the input signal range to the
compression threshold. Instead, we've allowed the RFX Compressor's Threshold
