dbx DriveRack PA2 Owner'S Manual Download

Page: 36 / 70

HiNt:

AFS works best when the signal entering the PA2’s inputs is sufficient. This requires proper gain staging

between the mixer and PA2. If the signal level is too low, AFS may be slow to respond to feedback. See

‘Manual System

Optimization Tips’ on page 18

for further information on gain structure and ringing out the system with AFS

Note:

Signals sent to the PA2’s LEFT and RIGHT inputs are summed to mono before entering AFS for analysis. If the

signal feeding one of the PA2’s inputs is polarity inverted, AFS will not be able to detect feedback – as the feedback will
cancel out before being analyzed. If you experience problems with AFS not detecting feedback, check the polarity of the
signals/cables feeding the PA2’s inputs to ensure they have the same polarity.

AFS Parameters

The AFS menu can be accessed by pressing the

AFS

button. Turn the

DATA

wheel to scroll through the list of parameters.

Press the

DATA

wheel to edit a selection.

•

AFS

[ON, OFF]

Turns the AFS module on or off. If AFS is off, the filters are bypassed and the algorithm is halted (the filters are not
updated). If AFS is on, the filters are active and they are updated according to the currently selected mode (Fixed or Live).

WarNiNg!

If AFS is turned on and filters are set (in use), be careful when turning AFS off, as all filters will be

immediately removed from the signal path and sudden feedback could occur. It is recommended that you lower your
mixer output faders before turning AFS off.

•

CLEAR MODE

[NONE, LIVE ONLY, ALL]

This parameter selects which filters will be cleared when you perform the clear function. If the NONE option is selected,
filters cannot be cleared. If the LIVE ONLY option is selected, only the Live filters will be cleared when you perform the
clear function and the Fixed filters will be left alone. When the ALL option is selected, both Live and Fixed filters will be
cleared when performing the clear function.

•

CLEAR <PRESS SELECT>

Selecting this option then pressing the

DATA

wheel triggers the clear function, which removes set AFS filters. The clear

function allows you to either clear only the Live filters or all AFS filters so you can ring out the system for a new venue. The
CLEAR MODE parameter selects which filters will be cleared when performing the clear function.

•

MODE

[FIXED, LIVE]

This parameter determines whether the AFS algorithm will set Live or Fixed filters. Select the FIXED mode option to initially
ring out the system for optimal gain before feedback using the Fixed filters (the microphones should be active during this
procedure, but there should be no signal present at the microphones). Fixed filters are “static” and will remain set until you
manually clear them.

Once you have rung out the system with the Fixed filters, set the mode to LIVE to further protect the system from feedback
during the performance using the Live filters. In Live mode, AFS uses logic to determine what is feedback and what is
not. The enhanced AFS algorithm in the PA2 can better distinguish between progam material and feedback, dramatically
lowering the probability of false Live filters being set on feedback-like music content, such as a flute.

Live filters are “dynamic” and will update as feedback conditions change. When all of the Live filters have been set, they will