Optimod-Surround 8685 V1.0 Operating Manual - Orban

OPTIMOD SURROUND PROCESSOR OPERATION 3-53
A typical setting of the Bass>LFE BASS COUPLING control is 3 dB, which caps the possible
dynamic LFE boost at 3 dB. Some may prefer 0 dB, which precludes any dynamic
LFE boost.
2B Master Attack sets the attack time of the Two-Band Compressor master compressor
(above 200Hz).
2B Bass Attack sets the attack time of the Two-Band Compressor bass compressor
(below 200Hz).
2B Master Comp Ratio and 2B Bass Comp Ratio set the compression ratio of the
Master compressor and Bass compressor respectively at their thresholds of compression.
Beyond threshold, the ratio increases with increased gain reduction until it becomes
∞:1 at the amount of gain reduction (in dB) set by the 2B MASTER KNEE control.
When you adjust these controls, the thresholds of the multiband compressors
change automatically so that the total amount of gain reduction stays approximately
the same. (This automatic adjustment is internal to the 8685’s DSP; the MB
THRESH controls’ displayed settings do not show it.)
To achieve a classic soft knee characteristic, set the 2B MASTER COMP RATIO control to
1:1 and set the KNEE control to the gain reduction in dB at which you wish the compression
ratio to level off to ∞:1. The maximum setting produces the softest knee.
Setting the KNEE to 0 dB produces a classic hard knee curve with ∞:1 compression ratio
regardless of the setting of the 2B MASTER COMP RATIO control.
See Figure 3-2 on page 3-54 for the curves of output level vs. input level for various
settings of the KNEE and RATIO controls.
2B Knee (see 2B MASTER COMP RATIO above).
2B Breakpoint The release rate (measured in dB/second) in the 8685’s compressors
is constant when the gain reduction is higher than the control’s setting, and exponential
when the gain reduction is lower than the control’s setting.
When the release is exponential, the release rate is proportional to the amount of
gain reduction. Do not confuse this with the reverse exponential characteristic triggered
by setting the 2B RELEASE SHAPE control to EXPONENTIAL. In this case, release
commences slowly and then speeds up as it progresses.
The 2B BREAKPOINT control is only active when the 2B RELEASE SHAPE control is set to
LINEAR.
Compression-induced audio density remains constant when the gain reduction is
above the 2B BREAKPOINT setting. When the gain reduction is below the 2B
BREAKPOINT setting, density decreases proportionally to the amount of gain reduction.