# BFD with high pass filter



## gperkins_1973 (Aug 25, 2008)

Hi there,

I will be building two slot ported subs tuned to 15hz. I currently have a BFD DSP1100 but am wondering if behringer sell a BFD which has a High pass filter built into it. I know you can get the behringer mic2200 or the reckhorn B1 or B2 (I guess I would need two of these). Wondering if there a way to do it to make it simpler.

cheers

Graham


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## Ricci (May 23, 2007)

You can use a DCX2496 to get a roughly 15hz HPF. 

Either that or try a Rane PE-17 or a Symetrix 551.


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## gperkins_1973 (Aug 25, 2008)

Ricci,

Can you connect a Behringer mic2200 to a BFD and if so what is the likely hood of getting a hum.

Otherwise what is the best way to do it. I want to use my bfd for EQing but will need to apply a hpf to my proposed two ported subs. They will be tuned to 15hz with max excursion reaching 13hz at max power.

cheers

Graham


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## lsiberian (Mar 24, 2009)

Ricci said:


> You can use a DCX2496 to get a roughly 15hz HPF.
> 
> Either that or try a Rane PE-17 or a Symetrix 551.


I'm not aware of how to get a 15hz HPF off a DCX 2496 would you be so kind as to share the method for this. As far as I knew it only does filters down to 20hz.


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## gperkins_1973 (Aug 25, 2008)

Hi guys 

I just read what this guy did:



> but right now I have it set up so that the sub output from my receiver splits into 2 signals and feeds into channels 1 and 2 of the UltraGain, From there it jumps into Channels 1 and 2 of the Feedback Destroyer, then from there to channels 1 and 2 of the Crown amp.



He is using the behringer ultra gain MIC2200

Does this sound right?

The Reckhorn B2 has a 24db slope for the subsonic filter where as the Behringer only has a 12db slope which won't be any good for me and will cut out too many db's in the 10-20db range.

The Reckhorn has a L and R input and output so I guess it will be ok to split the signal from the onkyo into the L and R inputs on the reckhorn. The take the L and R outputs into the L and R inputs on the BFD and then take the L and R outputs to the inputs on the behringer ep4000 amp. Hey Presto! Job done. Or is it?

cheers

Graham


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

Sure, that will work but it’s a lot of trouble and extra cabling for a mono sub feed. Why not just set the EP4000 for parallel mode? That way you only need a single input to drive both channels.

Also, I’ve noticed a tendency for people with DIY subs to be all in a sweat about high pass filtering before determining if they even need one. For instance, you haven’t even got your subs up and running yet. A high pass isn’t needed unless you’re maxing them out. If you end up with a situation where your subs are so mundo that they’re loafing all the time, you don’t need a filter at all.

Regards,
Wayne


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## gperkins_1973 (Aug 25, 2008)

Wayne,

Cheers for that. Winisd is quoting max excursion at 11.6hz max output so hopefully I wont. I don't ever listen at max volume so I guess I should be ok.

cheers

Graham


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## Ricci (May 23, 2007)

lsiberian said:


> I'm not aware of how to get a 15hz HPF off a DCX 2496 would you be so kind as to share the method for this. As far as I knew it only does filters down to 20hz.


Technically you are correct. However if you get creative with the low shelving filter and perhaps a couple of bands of EQ you can get it down into the 15hz range. Illka had a really good post about how to do this somewhere. You have to do the same thing to get a sub 20hz filter with the MIC2200 too.


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## Ricci (May 23, 2007)

I don't think the Behringer is a 12db slope. I believe that it is 24db octave or even steeper. 

One reason to keep the channels split up for the BFD and to the 2 subs would be to EQ them differently or whatever, but since you have identical subs I don't see a need for this. Wayne's suggestion of running one line is much simpler.


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## gperkins_1973 (Aug 25, 2008)

Ricci,

It is defo a 12db high pass filter.

http://www.behringer.com/EN/Products/MIC2200.aspx

Thats fine as a fourth order high pass filter cuts the frequencies too much for my liking.

cheers

Graham


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## dascth (Jan 25, 2010)

Hey, not sure if anyone has thought of this, but could we find +/- 15v rails inside the BFD to power a high pass filter circuit? I'm looking at building my own and think it's a waste to have to assemble a 15v supply and have another piece that has to be plugged in. It'd be pretty sweet to install the filter directly inside the BFD for cosmetic reasons as well as saving $$$ on the supply.

Anyone done this or know the possible voltage rails inside the BFD?


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