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Of course, you can use the FINE button to fine tune to frequencies between the standard ISO frequencies (in
1/60-octave steps) within a range of 1/3 octave.
Hz
20 25 31,5 40 50 63 80 100 125 160 200 250 315 400 500 630 800
kHz
1 1,25 1,6 2 2,5 3,15 4 5 6,3 8 10 12,5 16 20
Tab. 4.2: standard ISO frequencies
4.3 Parametric equalizers
Parametric equalizers, unlike graphic EQs, allow for selecting both the processing frequency and the band-
width, so that it is possible to process any given signal in full detail. Naturally, this equalizer design can also
be used to filter unwanted signals, however, only if these signal have a fixed frequency. If the frequency
changes, the parametric equalizer would have to be readjusted all the time. The majority of (analog) parametric
EQs suffers from a quite fundamental drawback: they are operated by means of rotary controls, i.e. contrary
to graphic EQs, it is much more difficult to make necessary readjustments quickly.
4.4 The FEEDBACK DESTROYER PRO
As you have seen, suppressing feedback with a standard graphic and/or parametric equalizer often means that
you have to accept compromises. Since feedback signals fail to comply with the standard ISO frequencies of
graphic EQs and additionally can have changing frequencies, their suppression with a graphic equalizer is
more or less a matter of luck.
Example: lets assume a feedback signal at 1.8kHz is produced during a concert. To suppress it, youve got
to cut the 1.8kHz band on your EQ. However, since graphic equalizers only have 1.6 and 2kHz bands, you
might need to attenuate both bands. Result: although feedback will be eliminated due to the low filter quality,
you will also fade out many music signals which youd actually wish to keep. Additionally, cutting these
midrange frequencies also means that your P.A. system loses power and performance.
In theory, a parametric EQ can be used to suppress feedback by means of high filter qualities. However, your
tweeters may well have gone up in smoke before youve found the frequency at which feedback occurs and
managed to eliminate it by adjusting the filter frequency, bandwidth and gain accordingly. For this reason, the
FEEDBACK DESTROYER PRO also uses a highly optimized version of the automated, fully parametric filters
we designed for the BEHRINGER ULTRA-CURVE. With the FEEDBACK DESTROYER PRO your P.A. sys-
tem will be under your control again!
Unlike many conventional equalizers, the FEEDBACK DESTROYER PRO provides an impressive range of
features:
s If required, the FEEDBACK DESTROYER PRO detects and suppresses feedback automatically by ana-
lyzing the music signal and determining the frequency of the interference signal. Additionally, it calculates
the filter quality and attenuation necessary to fade out feedback.
s The FEEDBACK DESTROYER PRO calculates the filter quality with such a high precision that nothing but
the feedback signal will be filtered, while retaining the original music signal. This means increased P.A.
headroom and a more balanced, powerful and transparent sound image.
s With the FEEDBACK DESTROYER PRO almost all of the power delivered by the amps will reach the
speakers, because the precisely set, narrow-band filters reduce energy losses to a minimum.
s The filters can be operated both in manual and automatic mode. Naturally, you can combine both modes in
single programs.
s Clearly structured entry keys give you direct access to essential parameters, while the jog wheel allows
you to conveniently adjust them as desired. Favorite settings can be stored in 10 preset programs. Of
course, the FEEDBACK DESTROYER PRO fully integrates into any MIDI system.
s This enormous processing power is provided by a software-separated 24-bit Dual-Engine processor. The
FEEDBACK DESTROYER PRO precisely converts your music with 20-bit AD/DA converters using a pro-
level sampling rate of 46kHz. The high-grade components and circuitry make sure that the quality of the 24
fully parametric EQs meets studio standards.
4. TECHNICAL BACKGROUND