An
Introductory Guide to Subwoofers
Using the Behringer Feedback Destroyer
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Hey, what's the BFD?
Everyone seems perplexed by the different Behringer Feedback Destroyers. The first thing to do is NOT to actually read the massive book that comes with it. This device is intended to filter out feedback (aka microphone squeal), and that function is primary focus of the BFD owners manual. The current popularity of the BFD is because it can also function as digital stereo parametric equalizer with 10 preset filter groups, each group containing up to 12 stereo filters.
There are 3 versions of the BFD. The
original DSP1100P, the newer DSP1124P has 24bit A/D-D/A converters, and the
newest FBQ2496. The 2496 has 24/96 digital operation, 20 programmable filters
per channel.
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How do I connect the BFD to my system?
For those that haven't figured it out, the Behringer goes between the SUBwoofer output of your receiver or pre-pro (or the output from a separate active crossover), and the input of the power amp. (SUBwoofer out > BFD > power amp)
If you have a standard non-balanced SUBwoofer output (meaning you use RCA connectors) there are a couple of options. One can use a regular interconnect with RCA ends. Then buy mono not stereo RCA to 1/4" adapters to connect the interconnect to the back of the Behringer. These mono adaptors are available from Radio Shack (P/N 274-320) and look like this....
Another option is to buy or build a
cable like this. A good source for cables like this is Markertek
If you decide to build your own cables this Van den Hul webpage has a chart for different connectors and going from the various types of balanced circuits to unbalanced RCA connectors
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Note, on the back panel of the BFD
are two small black rectangular 'Operating Level' switches. For most home
users, these
should be set (pushed in) to the (-10 dBV) setting.
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On the left side of the BFD front panel are two vertical columns of LED's that light up indicating signal level. Always keep these operating in the green indicators. Higher levels, yellow and red LEDs on or flickering, mean the digital circuits are 'clipping' = overdriven = distortion. Adjust the output level from the LFE (sub) out so that only the green LEDs light up.
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A word of warning. If you are turning the BFD on or off, be sure your power amp is turned off. If you cycle the BFD on or off, and the power amp is turned on, a very loud thump will be sent through the speakers.
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Here's quick guide for setting
a single filter in preset filter group #5
1) With the BFD powered up, turn the Rotary dial until the #5 is seen in the digital readout window. This is preset filter group #5. This group has the filters set by default to 1/3rd octave (20/60) bandwidth. Note, you can change this bandwidth in step #4
2) Now press the Filter Select
button once, then turn the black Rotary dial. The number you chose is 1 of
12 filters in this group. Select #1.
3) Next press the Frequency button once. Now turn the Rotary
dial and chose the frequency you want to adjust. By default the filter choices are 1/3rd
octave apart (20Hz, 25Hz, 32Hz, 40Hz, etc) . Note that there's a difference
between .20 and 20. (.20 =200Hz, 20=20Hz). Later we'll cover how to chose
frequencies other than those with 1/3rd octave spacing.
4) Next press the Bandwidth button once. You'll see the number 20 in the readout. This means the filter is 20/60, or 1/3rd octave wide. The range of available bandwidths is from 1/60 (one 60th octave) to 120/60 (2 full octaves). The choice of bandwidth determines the width of the filter. Turn the Rotary dial to chose the bandwidth you want.
5) Next press the Gain button once. Turning the Rotary dial determines the amount of cut or boost.
6) Finally press the Store button twice. When a filter is stored the red LEDs will light up in the long front panel horizontal readout and the LED in the Store button will stop flashing and glow green. In the example below 8 stereo filters have been stored in the unit.
You have now set your first filter. Repeat this process for each filter you need, choosing a different filter number (step #1) for each filter needed
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Using the Fine (1/60 octave) button. When you need to cut or boost frequencies that are between the standard 1/3rd octave spacing, you use this button. The number you dial in adds or subtracts from the standard 1/3rd octave frequency you set with the Frequency button (instruction #3 above).
To use the Fine (1/60 octave) button you need to reference the frequency chart in the BFD owners manual (page 20) .The chart has dark columns showing the standard 1/3rd octave (ISO) frequencies, and the adjustments needed with the Fine (1/60 octave) button to customize the frequency.
Example #1, you need a set filter at 66Hz. First use the Frequency button to set the raw frequency to 63Hz (the standard ISO frequency). Now look at the chart and see 66Hz is in the +4/60 column. Now push the Fine (1/60 octave) button and dial in +4. You've now set a 66Hz frequency
Example #2, you need a set
filter at 27Hz. First use the Frequency button to set the raw frequency
to 25Hz (the standard ISO frequency). Now look at the chart and see 27Hz is in
the +6/60 column. Now push the Fine (1/60 octave) button and dial
in +6. You've now set a 27Hz frequency
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NOTE, after
ANY change in ANY setting, it's necessary to tap the black Store
button twice so the unit will store the change in memory. The LED in
the black Store button will flash until the new settings are
saved.
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What's a
'House Curve'?
Most people find a so called 'flat' response
a bit boring, so they dial in some EQ to suit their taste. That's what's
referred to as a 'house curve'.
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Want custom EQ settings, one for HT, and one for music?
Choose preset filter group #4 and dial in a custom curve for your music playback. Then set preset filter group #5 using a custom curve for your HT settings. Now it's a simple task to rotate the dial between preset #4 and preset #5 to switch between the HT and music settings.
What's the easiest way to do this?
Copy your custom settings from their
current preset to another preset, then adjust that new preset for your
particular need/wants. Turn the black Rotary dial to select your current
preset. Then press the Store button once (the LED in the Store
button will start flashing).
Next turn the black Rotary dial to the preset you want for your new
preset (any number except your existing preset will work). Next push the black Store
button twice.
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Click HERE for the next page of the DSP1100/1124P instructions
Click HERE for the FBG2496 instructions (under construction)
Click HERE for the DEQ2496 instructions (under construction)
Click HERE to return to the Table of Contents