Feedback destroyers

JerryLove

JerryLove

Audioholic Ninja
Such as the Behringer FBQ2496. What do they do (obviously adjust certain frequencies based on some criteria)... but... what do they *do*?
 
highfigh

highfigh

Seriously, I have no life.
Such as the Behringer FBQ2496. What do they do (obviously adjust certain frequencies based on some criteria)... but... what do they *do*?
They see a sudden spike in the amplitude of the feedback frequency and attenuate it. This has no use in a home theater or regular stereo system, it's made for live sound where a mic or turntable can receive signal from the speakers and pass it on to the input, which then sends it on to the amplifier and continuing the feedback cycle. Since a tape deck, DVD, tuner, CD or Laser disc player can't be made to feed back, it's not something we need to look for in a HT or stereo system unless we'll be using it for Karaoke or DJ'ing. Without seeing data from the manufacturer, I would bet that it's a "brick wall limiter", which should be pretty self explanatory.
 
WaynePflughaupt

WaynePflughaupt

Audioholic Samurai
It's not a dynamics processor; there are no limiters involved. When it sees a signal spike due to feedback, it notches the offending frequency out with a super-narrow parametric filter. The filter stays in place at that point; otherwise the feedback would return.

Regards,
Wayne A. Pflughaupt
 
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highfigh

highfigh

Seriously, I have no life.
It's not a dynamics processor; there are no limiters involved. When it sees a signal spike due to feedback, it notches the offending frequency out with a super-narrow parametric filter. The filter stays in place at that point; otherwise the feedback would return.

Regards,
Wayne A. Pflughaupt
I guess I should have been more specific about how narrow the band would be. The rest is splitting hairs- it uses a parametric EQ to affect the dynamic change due to the feedback.
 
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WaynePflughaupt

WaynePflughaupt

Audioholic Samurai
Notch filters have no effect on the dynamic range of the frequency they’re affecting. The affected frequency will rise and fall in tandem with the signal; it’s just at a lower level than the rest of it.

Regards,
Wayne A. Pflughaupt
 
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MidnightSensi

MidnightSensi

Audioholic Samurai
They have software that senses constant higher amplitudes/noise when no signal is applied and cut that frequency with a very tight Q to prevent influencing the stuff around it that doesn't need to be cut.

Since a tape deck, DVD, tuner, CD or Laser disc player can't be made to feed back, it's not something we need to look for in a HT or stereo system unless we'll be using it for Karaoke or DJ'ing. Without seeing data from the manufacturer, I would bet that it's a "brick wall limiter", which should be pretty self explanatory.
You're thinking of a limiter. The notch filters on a feedback destroyer aren't actively set, so if you get turntable feedback or bass rumble it won't save you.

Limiters will protect against that sort of feedback. I actually have limiters on all my channels except my rears (I will eventually add a unit there too). Where limiters are nice in home theater is you can set the limiters just below the clip point of your amplifiers, or where your drivers start loosing composure, and then you don't need to worry as much about a pop, cap discharge or someone too heavy with the volume from blowing your speakers.

I never hit my limiters in my home theater (especially not now), but it is a comforting thing to have. I have them all set to hard knee inf:1, so when they do hit them it is a brick wall.
 
adwilk

adwilk

Audioholic Ninja
Can't that particular unit in question be used as an xover for a sub?
 
highfigh

highfigh

Seriously, I have no life.
They have software that senses constant higher amplitudes/noise when no signal is applied and cut that frequency with a very tight Q to prevent influencing the stuff around it that doesn't need to be cut.



You're thinking of a limiter. The notch filters on a feedback destroyer aren't actively set, so if you get turntable feedback or bass rumble it won't save you.

Limiters will protect against that sort of feedback. I actually have limiters on all my channels except my rears (I will eventually add a unit there too). Where limiters are nice in home theater is you can set the limiters just below the clip point of your amplifiers, or where your drivers start loosing composure, and then you don't need to worry as much about a pop, cap discharge or someone too heavy with the volume from blowing your speakers.

I never hit my limiters in my home theater (especially not now), but it is a comforting thing to have. I have them all set to hard knee inf:1, so when they do hit them it is a brick wall.
I know what a limiter is but as I said, without seeing data from the manufacturer, it's hard to say exactly how they do it with theirs.

If they're not actively set, how do they sense what frequency needs to be clamped down?
 
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