# My Behringer DSP setup for dipole sub



## giskard (Mar 14, 2012)

I have a pair of 15" drivers in a W-frame dipole sub enclosure which is a slightly enlarged version of Linkwitz's W-frame dipole sub design which uses 12" drivers. 

For the 6dB/oct equalization I used the DSP built into my NU-1000DSP.

The first filter implements a lowpass shelf with a pole at 20 Hz and a zero at sqrt(32) times higher frequency. (derived from the 15 dB boost or cut setting) The 2nd filter also implements a lowpass shelf but whose pole sits right on top of the first filter's zero, cancelling it. The 3rd filter does the same for the 2nd filter, although I would call it optional because the effect in the sub's passband is tiny (xover to mains is 80 Hz). 

So the filter is mathematically correct but with a hipass rolloff at 20 Hz. 

I then ran my receiver's Audyssey setup. The bass in-room is noticeably smoother than my old monopole sub.

I have yet to run RE on this setup to fine-tune the crossover'ing to the mains and to notch out any peaks from the enclosure cavity resonance (probably in the range of 150 Hz)


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## giskard (Mar 14, 2012)

Here is the main sub filtering/xovering.

I have a hipass at 30 Hz because my old calcs show that the drivers will run out of excursion there. I will revisit this and use the Behringer's dynamic EQ to limit excursion only at high SPL's.

The lopass at 200 Hz is set way high so it won't interfere with the receiver's 80 Hz crossover. I have yet to run RE to fine tune the crossover.

The gain is set so that the output clips just before the input does.


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## Wayne A. Pflughaupt (Apr 13, 2006)

giskard said:


> I have a pair of 15" drivers in a W-frame dipole sub enclosure which is a slightly enlarged version of Linkwitz's W-frame dipole sub design which uses 12" drivers.
> 
> >snip<
> 
> I have yet to run RE on this setup to fine-tune the crossover'ing to the mains and to notch out any peaks from the enclosure cavity resonance (probably in the range of 150 Hz)


I can’t tell from your post what exactly it is you’ve accomplished or what you’re trying to show us. It’s hard to imagine that a subwoofer would require this kind of equalization. :scratch:

That said, there is some “term confusion” here. Referring to a filter as “shelving high pass" etc. is something of a misnomer. High or low shelving filters (like you're showing us here) aren’t the same as low or high pass filters because the former don’t have infinite slopes.

Regards,
Wayne


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## JohnM (Apr 11, 2006)

It's a dipole sub, so needs specific EQ with a 6 dB/octave slope that starts at a frequency that depends on the size of the baffle. The second order low/high pass filters typically found in parametric equalisers have 12 dB/octave slopes, shelving filters have slopes up to 6 dB/octave or 12 dB/octave depending on their implementation and shelf gain. I think the post is explaining how to get a consistent 6 dB/octave slope over a significant frequency span as required for a dipole.


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