Behringer Feedback Destroyer

[Tungsten06GT]

Hey guys, I just ordered the Behringer Feedback Destroyer the other day for EQ'ing my sub, and was wondering if those who have it leave it on all the time or shut it down after use. It doesn't seem like it has an auto on feature or goes into standby at all.

Also, I'd like to hear anyone else's experience with using the device. I've already checked out The Home Theater Shack's writeup on it, so I'm prepare for when it comes... Thanks!

 

[gmichael]

I leave mine on 24/7. It made a great difference with my sub. Nice investment.

 

[Tungsten06GT]

I leave mine on 24/7. It made a great difference with my sub. Nice investment.

Awesome, glad to hear. I've been playing around with an Excel spreadsheet where you enter in your current data, then set the filters to see the expected response. Did you use that and if so, did your results match up pretty well when you set the BFD and re-measured? Also, I should work on pulling down peaks and not boosting nulls right?

 

[gmichael]

Awesome, glad to hear. I've been playing around with an Excel spreadsheet where you enter in your current data, then set the filters to see the expected response. Did you use that and if so, did your results match up pretty well when you set the BFD and re-measured? Also, I should work on pulling down peaks and not boosting nulls right?

Yes, but my Rat Shack meter sh,t the bed before I could confirm the end results. It does however sound very good. No more one note wonder. All the bass notes sound even.

Pulling down peaks is better than boosting nulls. Nulls are often due to room cancelations. Boosting can often just add distortion and not increase the level of where you are sitting/testing from. You can boost a little though. I wouldn't go over +3 db.

 

[WaynePflughaupt]

Also, I should work on pulling down peaks and not boosting nulls right?

True, a null won't respond to a booted filter. But not all depressions in response are true nulls. Nulls are easily recognizable, typically they’re very deep and very narrow. Depressions that aren’t nulls can be boosted. Typically they’ll be broader than a null and not terribly deep. Also study your graph to see if a depression isn’t merely a low point between two peaks.

The graphs below show the difference between a null and non-null depressions.

Graph With Null @ 90 Hz and 150 Hz

Graph With Depressions But No Nulls​

Nulls aside - despite all the myths and rumors that circulate, the only real rules-of-thumb for EQ boosting is that you shouldn’t boost a ported sub below the frequency the port is tuned to, and you shouldn’t boost ultra-narrow filters. Other than that any equalizing, boosting or cutting is relative to the amount of headroom your sub has. If you only apply EQ cuts but had to increase your sub’s SPL by 8 dB after equalizing, you can’t reasonably say you “didn’t boost anything.”

Regards,
Wayne A. Pflughaupt

 

[Tungsten06GT]

That's interesting. Ok, here is my actual response using a Radioshack digital spl meter, and I applied the correction factors associated with the meter.

The 0 y-axis corresponds to 10 Hz, whereas the 10th bar to the right represents 100 Hz, each grid is incremented by 10 Hz logarithmically (i.e. 10/20/30, you get the point!). Don't worry about the actual output, the spreadsheet just centered everything around 0 to get a perspective for how the response varies.

The sub is rated down to 16Hz, with room gain giving you a little more so I'm not surprised to see extension down to 12Hz (it is a sealed design). Based upon this chart, would you say I don't have any nulls? Also, is it a good idea to bring everything down to where 20Hz is baselined, rather than boost at 20Hz and flatten out from there?

Thanks again for the great input!

 

[WaynePflughaupt]

Based upon this chart, would you say I don't have any nulls? Also, is it a good idea to bring everything down to where 20Hz is baselined, rather than boost at 20Hz and flatten out from there?

Nope, no nulls there.

I’d EQ with a combination of boosts and cuts, rferenced to either the 0 dB or 3 dB line. Cutting everything down to the 20 Hz level will net an overall gain reduction of something like 20 dB. Using an equalizer as a defacto volume control is bad form.

Regards,
Wayne A. Pflughaupt

 

[Tungsten06GT]

Nope, no nulls there.

I’d EQ with a combination of boosts and cuts, rferenced to either the 0 dB or 3 dB line. Cutting everything down to the 20 Hz level will net an overall gain reduction of something like 20 dB. Using an equalizer as a defacto volume control is bad form.

Regards,
Wayne A. Pflughaupt

Thanks a ton! I'll post my results and impressions of the new response once I get the BFD.