Behringer Feedback Destroyer FBQ1000 用户手册

FEEDBACK DESTROYER FBQ1000 User Manual

The philosophy behind BEHRINGER products guarantees a no-compromise 

circuit design and employs the best choice of components. A 24-bit DSP is 

used as the heart of the FEEDBACK DESTROYER, which belongs to the best 

components available owing to its outstanding specifications and excellent sonic 

characteristics. What is more, high-quality 24-bit A/D and D/A converters ensure 

the accurate processing of all signals. Additionally, the FEEDBACK DESTROYER 

uses high-quality resistors and capacitors with very tight tolerances, high-grade 

switches, and further selected components.
The FEEDBACK DESTROYER employs SMD technology (Surface Mounted Device). 

These subminiature components known from aerospace technology allow for 

an extreme packing density and improve the unit’s reliability even further. 

Additionally, the FBQ1000 was manufactured in compliance with an ISO9000 

certified management system.

Your FEEDBACK DESTROYER was carefully packed in the factory and 

the packaging was designed to protect the unit from rough handling. 

Nevertheless, we recommend that you carefully examine the packaging and its 

contents for any signs of physical damage, which may have occurred in transit. 

The BEHRINGER FEEDBACK DESTROYER requires one standard 19" unit of 

rack space. Please allow at least an additional 4" depth for the connectors on the 

back panel.
Be sure that there is enough space around the unit for cooling and please do not 

place the FEEDBACK DESTROYER on high-temperature devices such as power 

amplifiers, etc. to avoid overheating.

The fuse holder on the female mains connector has 3 triangular markings, with 

two of these triangles opposing each other. The FEEDBACK DESTROYER is set to the 

operating voltage printed next to these markers and can be set to another voltage 

by turning the fuse holder by 180°. CAUTION: This instruction does not apply to 

export models exclusively designed, e.g. for 115-V operation!
Please use the enclosed power cord to connect the unit to the mains. The cord 

complies with all applicable safety standards.

As a standard, the BEHRINGER FEEDBACK DESTROYER is equipped with 

electronically servo-balanced inputs and outputs. The circuit design features 

automatic hum and noise reduction for balanced signals and thus allows for 

trouble-free operation, even at high operating levels. Externally induced mains 

hum, etc. will be effectively suppressed. The automatic servo-function recognizes 

the presence of unbalanced connectors and adjusts the nominal level internally 

to avoid level differences between the input and output signals (6-dB correction).
The MIDI interfaces IN, OUT, and THRU are on standardized DIN connectors. 

Data are transmitted via potential-free opto couplers.

A feedback loop is produced when a microphone signal is reproduced by an 

amplification system and is subsequently picked up again (with identical phase) 

by the microphone. If this happens repeatedly, such a feedback loop can become 

ever more persistent.

Fig. 1.1: How a feedback loop is produced

1.3.1  Background: front of house mix (FOH)
There are two main sections in any sound reinforcement system, which are liable 

to produce feedback: the first section is the so-called front of house mix (FOH), 

i.e. the “public address” mix, which is reproduced by one or several amplifiers 

plus several loudspeakers directed at the audience.

1.3.2  Background: monitor mix
The monitor mix, which is often derived from the same console, feeds one or 

several stage-mount monitor speakers. Unlike FOH systems, stage monitors 

are used to provide the individual musicians with a monitor signal, because it 

is often difficult to hear oneself or each other on the stage, which can be due 

to the high volume levels produced by the FOH systems, or to different volume 

levels of the stage-mount instruments and amplifiers. It is therefore not unusual 

to give each musician his or her own monitor speaker, which is why there are 

usually several monitor speakers placed along the stage. This is the only way to 

provide each musician with a directed and focused monitor signal. In an ideal 

situation, each monitor provides a specific mix, comprising e.g. vocals, drums and 

keyboards, for each individual musician on the stage.
Unfortunately, it is anything but easy to find perfect positions for the various 

stage monitors, because the distance between speaker and microphone must be 

kept very short, which in turn increases the risk of feedback.