Omnia 4.5 Use and Installation Guide – Ver 1.00a
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L(ow) and H(igh) Band AGC Windows
Each of the AGC's has its own set of controls similar to those in the Wideband AGC section. The four
controls in these windows, Attack, Release, Make-Up Gain and Gate Threshold, and the two parameter
selections, RTP Speed and RTP Level, function like those in the Wideband AGC window. Adjustment
strategies are similar, however in the two-band AGC sections adjustments are on a "per-frequency band"
basis.
Low Band AGC shown as example – high band is identical
As with any multiband processor, improper adjustment can exaggerate one band of frequencies over
another. In this case the low frequencies vs. the midrange and high frequencies. Both bands incorporate a
Return To Platform (RTP) feature similar to that available within the Wideband AGC process block. When
the RTP function is set to a value other than Freeze, the band gain will be forced to recover its gain to a
static value higher than might be achieved if the control was set to Freeze. This will reduce hiss and other
noise that might be heard if the bands had recovered to low values of gain reduction when the gate function
kicked in. The RTP levels can be tailored for each of the two AGC bands as desired.
Use the RTP Speed to set the amount of time it will take the AGC to return to the set platform level. There
are four choices: Freeze, Slow, Med, and Fast. The default setting is Freeze, which freezes the gain
whenever gating occurs. Therefore, to activate the RTP for that band, just select a speed. As mentioned
previously, the RTP speed is slightly affected by the value of the attack time that is set for that band. The
opposite is not true: RTP Speed does not affect the operation of the attack/release functions. Freeze can be
considered the “off “ mode for the RTP function.
Use RTP Level to set the platform level. There are three choices: -5dB, -10dB and –15dB. The default
value is –10dB. Keep in mind that the RTP function must be activated for this parameter to be relevant.
Note also that for some presets, small changes we made to the compression ratios will affect the displayed
value of the RTP. For instance, if you set the RTP gain value to "10" but notice that the band gain recovers
to –12 when gated, it is because we have set a slightly higher ratio for that band. Note that ratios are critical
to the open and musical sound of the Omnia4.5-fm, and therefore we do not offer them as user adjustments.
