Section 23: Pro's Guide
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I then move on to the next ADF filter, setting it to “D,” and repeat the process until I’ve caught the
first 5 or 6 ringing frequencies (maybe more, in a tough situation). Then I examine the frequen-
cies of the filters put in place automatically by the ADF. If it turns out that some of them are very
close together, I’ll pick an in-between frequency and widen a filter there, eliminating others close
by, in order to place fewer filters in the signal path. Also, since 1/10 of an octave is a very narrow
filter, I sometimes widen other filters as well, especially considering that I’ve made my tests with a
stationary mic. As soon as the mic is moved, the feedback frequencies will shift, and I want to
cover that situation as well. Besides experimenting with widening filters, I also set an unused ADF
filter to “D” for the show, to catch feedback that may occur under performance conditions. The
beauty of the Sabine FBX filters is how well they detect feedback even when music is playing!
After I’ve completed the ringing out process, I’ll try and use the ADF’s integral delay and gate to
further assist me in achieving the greatest gain before feedback. With the gate set at a very low
threshold, but above the room ambience, the sound of a podium mic or omnidirectional lavaliere
can often be improved. And by delaying the signal ever so slightly (perhaps 10 milliseconds),
another slight increase in gain before feedback (especially at low frequencies) can be realized.
The ADF has become an indispensable tool in my quest for the maximum gain before feedback,
and I’m sure you’ll find the same results.