# BFD 1124P High Pass Filter



## blizzisu (Dec 3, 2008)

I have been using WinISD to model various designs for a HT sub I am planning to build. When modeling I apply a high pass filter to prevent exceeding max cone excursion at low hz levels. For example, is it possible to apply a 3rd order high pass filter at 14.25hz using the BFD 1124P? If so, how easy is it to do for someone who has never used a DSP before?


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## brucek (Apr 11, 2006)

> is it possible to apply a 3rd order high pass filter at 14.25hz using the BFD 1124P?


No, you can not do high pass filters with a BFD.

brucek


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## blizzisu (Dec 3, 2008)

brucek said:


> No, you can not do high pass filters with a BFD.
> 
> brucek


Is a high pass filter something that is normally integrated into the amp, or are there other DSPs out there that can do high pass filters?


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

While many (if not most) pro audio equalizers have on-board low- and high-pass filters, the BFD does not. As you may know, a high- (or low-) pass filters continually roll out response at a set rate per octave. Since the BFD has no HP or LP filters the best it can offer is one if its standard EQ filters. These will eventually flatten, not continually drop.

Many amps have low pass filters, but I’ve never seen one as low as 14 Hz. Typically you will need an outboard device to accomplish this.

Regards,
Wayne


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## blizzisu (Dec 3, 2008)

Wayne A. Pflughaupt said:


> While many (if not most) pro audio equalizers have on-board low- and high-pass filters, the BFD does not. As you may know, a high- (or low-) pass filters continually roll out response at a set rate per octave. Since the BFD has no HP or LP filters the best it can offer is one if its standard EQ filters. These will eventually flatten, not continually drop.
> 
> Many amps have low pass filters, but I’ve never seen one as low as 14 Hz. Typically you will need an outboard device to accomplish this.
> 
> ...


Do you have any recommendations on devices that offer an adjustable high pass filter? I have found quite a few subwoofer amps that have high pass filters than can be adjusted by replacing the resistors, but, I would prefer a device that is adjustable on the fly and can be used with any amp.


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## blizzisu (Dec 3, 2008)

blizzisu said:


> Do you have any recommendations on devices that offer an adjustable high pass filter? I have found quite a few subwoofer amps that have high pass filters than can be adjusted by replacing the resistors, but, I would prefer a device that is adjustable on the fly and can be used with any amp.


I answered my own question. I found the Reckhorn B-1, ED eq.2, and the DCX2496 all do what I need.


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

You might want to avoid the B1. IIR brucek did a review on one a while back and found that it has inadequate capacitors that will eventually self destruct.

Regards,
Wayne


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## Mike P. (Apr 6, 2007)

I have not heard of any issues with the Reckhorn B1. It has been stated that the ED eq.2 does not work well with pro amps due to it's inability to boost the input voltage.


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

My goof, it was the FI electronic crossover, not the B1. Still, brucek's findings with the F1 don't exactly inspire confidence...

http://www.hometheatershack.com/for...khorn-f-1-active-crossover-modifications.html

Regards,
Wayne


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