Question to anyone with a BFD, (1 Viewer)

[Jones_Rush]

In the manual of the Behringer Feedback Destoyer, it says that it can attenuate each frequency up to -48db. Now, is there a practical limitation to how much I can attenuate ?, or can I just safely attenuate with full -48db if needed ?. I can't remember where, but I think that I've read somewhere that attenuating with the BFD with more than -12-15db might produce some artifacts. Can anyone confirm ?.

 

[Wayne A. Pflughaupt]

Jones,

The question is moot because you won’t need to attenuate anything even close to 48dB. The second question, I’ve seen people use cuts of more than 15dB with no problem.

Regards,
Wayne A. Pflughaupt

 

[Stephen Dodds]

But yes, the more you attenuate the more information you lose. The BFD uses digital gain to drop the levels, which means the more you cut the more bits you lose.


Steve

 

[Jones_Rush]

But yes, the more you attenuate the more information you lose. The BFD uses digital gain to drop the levels, which means the more you cut the more bits you lose.

But Stephen, for example, if I attenuate 80-60hz by -48db, 40hz-20hz is still un-attenuated, so why am I loosing anything at these frequencies ?. I thought you only lose information, all around the frequency domain, when you gain some frequency (since then it needs to lower all the other frequencies, in order to make that frequency appear higher in SPL).

 

[Brian Fellmeth]

Both Wayne and Stephen assumed that you are using the filters to equalize, which is not what you are doing. You are trying to use the filters to create a shelf. I highly recommend you work with the simulator and find the combination of filters that best acomplishes your goal of a low pass shelf at about 40 Hz. By all means dial them all the way to -48 dB, and use a narrow bandwidth.

 

[Brian Fellmeth]

I fired up the simulater, and here is what works. Set 8 filters at 50,55,60,68,75,82,90 and 100 Hz. All minimal width (1/60 Octave), all maximum cut -48dB. The result is down 3 dB at 40, down 8dB at 45 and down at least 30dB from 50 to over 100.

Your original question about artifacts- not a concern, since your large cuts are to snuff a signal out entirely. The artifact would apply with a large cut in a portion of the signal that is still audible since the engine would not have enough bit depth left to supply a smooth signal to the D to A converter.

 

[Jones_Rush]

Thanks guys.

 

[Brian-K-Owens]

I just use 2 bands of mine at 1.6kHz and 2.0kHz @ the widest bandwidth possible with -48dB gain setting (my preamp only has a 100 Hz lowpass filter). Not sure where the net cutoff frequency ends up, but you cannot hear ANYTHING but bass from the sub.

Brian

 

[Wayne A. Pflughaupt]

I’ve seen people who applied too many negative filters (when equalizing subs) to the point that the BFD would no longer pass a signal, so this is something you will have to look out for. Perhaps there is a compensation that can be applied (I don’t have a BFD myself)?

Regards,
Wayne A. Pflughaupt