Behringer Feedback Destroyer FBQ1000 ユーザーズマニュアル

FEEDBACK DESTROYER FBQ1000 User Manual

The three remaining filters (all set to Auto mode “AU”, see chapter 6.3) are used 

to detect and suppress new feedback frequencies, which can be produced, 

e.g. when the singer moves around the stage with the vocal mic in his/her hand. 

Since the FBQ1000 can by no means “know” whether or not the risk of feedback 

has been eliminated (e.g. when the singer moves to another position), the first 

AU filter of the unit locks to the detected frequency, while the remaining two 

AU filters are used to suppress any new trouble frequencies that may occur. 

Only when all AU filters have been used, will the first AU filter used (here: 10) 

be unlocked, so as to be able to detect new feedback frequencies.
Basically, all active filters (both in “AU” or “SI” mode) are represented by flashing 

LEDs in the STATUS INDICATOR  

(2)

. When feedback has been detected and is 

being suppressed, the associated filter LED lights up constantly. Filters set to 

Parametric EQ mode (see chapter 6.2) also have constantly lit LEDs.

With the FBQ1000 you can improve the protection against feedback even before 

the show begins, by “tuning in” your sound reinforcement system. We already 

dealt with this in chapter 3. But now it’s not about using a preset, but about 

how to determine in which modes the filters are used: Set some of the filters to 

Single-Shot mode (see  

(7)

).

First, let’s take a look at the monitor path: Open all microphone channels, turn up 

the Aux Send controls on all channels you wish to route to the monitor mix, 

then slowly move up the monitor master faders. For the front mix do as follows: 

Slowly move up the channel and master faders. In both cases, the first feedback 

frequencies can be heard after some time.
Without the FEEDBACK DESTROYER you could not increase the volume level of 

your system any further. With the FBQ1000, however, you can considerably 

enhance the system headroom! Let the Single-Shot filters on the FBQ1000 

suppress feedback as it occurs. Then cut back the volume to the level required 

for the show. In this way, you can be sure that there is enough system headroom 

should it become necessary to raise the volume level during the concert.
Experience has shown that musicians want to have the volume of their 

instrument increased on the monitor as the concert goes on. With the FEEDBACK 

DESTROYER you can turn up the volume without having to fear feedback 

problems. When the show begins you should set several filters to Auto mode, 

in order to suppress feedback produced by “moving” (vocal) microphones. 

More information on Auto mode can be found in chapters 5 and 6.3.

The individual filters on the BEHRINGER FEEDBACK DESTROYER can operate in 

four different modes (see  

(7)

). An additional mode called “Locked” mode will be 

described specifically. Basically, each of the 2 x 12 filters on the FBQ1000 

can be set to any of the four operating modes. To meet more complex 

requirements with regard to flexible signal processing, these modes can be 

combined in a program and stored in a preset.

In Off mode, the corresponding filter is deactivated and can be activated by 

selecting one of the modes described below.

To raise or lower specific frequencies in level, you can select these frequencies 

directly by setting the manual filters to Parametric EQ mode. Each filter has 

the functionality of a fully parametric EQ, i.e. you can set the center frequency 

(FREQUENCY key  

(10)

), the bandwidth (BANDWIDTH key  

(12)

) and the amount of 

boost/cut (in dB) using the GAIN key  

(13)

.

Automatic filters operate in two modes: Single-Shot (SI) and Auto mode (AU). 

In order to find a feedback frequency, the FEEDBACK DESTROYER divides the 

entire frequency band into 1/60 octave steps (20 Hz to 20 kHz) and determines 

the respective level of these individual bands. The unit then compares this value 

to the level of the entire signal. The difference between these levels determines 

whether a filter is set or not. The FEEDBACK DESTROYER gives you the unique 

possibility of adapting this parameter according to your own needs. You can edit 

the feedback sensitivity (i.e. the difference value) within a range from -3 to -9 dB, 

in 1-dB steps: Simultaneously press the FILTER MODE and GAIN keys, then use 

the JOG WHEEL to select a value. The standard value for this parameter is -6 dB, 

which provides for an optimum detection of feedback in most applications.
Example: During a pure speech transmission, the feedback sensitivity can be 

lowered to -9 dB. In this way, the algorithm would recognize and suppress 

feedback even faster. On the other hand, a higher setting, e.g. -3 dB, allows you 

to leave those signals unaffected which you don’t want to suppress (e.g. guitar or 

keyboard signals).
Filters in Single-Shot mode automatically analyze the music signal to detect 

feedback frequencies. Having detected such a frequency, the filter automatically 

configures its parameters to suppress feedback as efficiently as possible. As the 

filter is locked to the detected frequency, this mode is ideally suited to suppress 

feedback of constant frequency. Possible applications are “fixed-position” 

microphones (e.g. on the drums). After the filter has adjusted itself automatically, 

it enters a special Locked mode (see chapter 6.4), which means that although the 

frequency remains fixed, the width and depth of the filter are still being adapted 

to the feedback frequency, i.e. the width is increased as soon as the feedback 

frequency begins to shift, and the gain is cut if feedback prevails. The gain is not 

reduced to prevent feedback from recurring.
All microphones that are moved during a performance (e.g. vocal mics) 

very often have varying feedback frequencies. This type of feedback should be 

suppressed in Auto mode. As in Single-Shot mode, the filter automatically 

selects an ideal setting for feedback suppression. However, in Auto mode the 

first AU filter set is unlocked to suppress new feedback. The optimum frequency 

is selected automatically and the filter is set to narrow-band mode, so as to 

influence the music signal as little as possible. If your music contains wanted 

feedback elements (e.g. guitar feedback), it is highly probable that these will be 

suppressed too in Auto mode, because it is impossible from a physical point of 

view to distinguish “wanted” from “unwanted” feedback. Please read chapter 2.3 

to find some information on how to work around this situation.

When the FBQ1000 detects a feedback frequency in Single-Shot mode 

(see chapter 6.3), it automatically enters Locked mode, i.e. the filter locks to the 

trouble frequency and “keeps an eye” on it. To unlock such a filter, you need to 

switch it back to Single-Shot mode (see  

(7)

  and chapter 7.2).

In order to store your favorite settings, the FBQ1000 has ten user presets and one 

default preset. All operating parameters can be stored, so that your programs 

are recalled in full detail. Owing to state-of-the-art circuitry, no internal battery 

is needed, hence the memory contents will not get lost. In the default preset 

(Display: “--”), which serves as a starting point for your own programs, all filters 

remain in Parametric EQ mode, with bandwidth set to 1 octave, frequency to 

500 Hz and 0 dB gain.