"Small Box" to 1 / 6 unit (you can have six in a rack unit).
It works with a processor that analyzes the frequencies that go on and feedback filter of 1 / 5 or 1 / 10 octave (ie less than 31 bands of eq 1 / 3 octave ).
Sm version has XLR and a 48v power supply for microphones (switch back).
It can also operate in a loop with an impedance insert line kind of way (the second selector switch = high or low impedance).
It is only mono, so to use between a console and an amp, it takes 2 cans (or FBX 2400)
Very easy to use, simply mount the volume knob of the table (or other) connected with the micro course and the small box filter successively different frequencies that go on feedback (until 8 in the case of this version) .
Afterwards, he must still fall a little volume to the console after analyzing the frequency of feedback.
We must also adjust the input gain of the device using the knob on the front and the scale of LEDs.
There are other features such as a switch for setting a number of the first filter.
The first filters can be set at the start, leaving the last two or three in "dynamic", ie in case of attachment to other frequencies while you play.
The XLR version is rather intended to be placed between the microphone and console.
Frequencies being "filtered" to 1 / 10 octave (very very close), you hear almost no missing frequencies in the audio spectrum (which is not the case if you use a egualiseur 31 bands! ).
In short, she knows to be forgotten.
These filters Sabine FBX "feedback exterminator" (in this format or rack) are expensive but are in OCCAZ at great prices (cf. the well known auction site!).
The big advantage is that you can set before starting the repeated or the small concert (especially configuration without cafe-concert sound engineer behind the console).
The flaw is that it has a mono channel (see specifications).
I put 8 for that.