# Sub EQ / room calibration equipment question



## fackamato (Sep 19, 2007)

Hi,

I'm going to build a sealed sub with a Maelstrom-X from Exodus Audio, and I think I need an EQ for the extension. Which EQ can go down as low as 10 or 5Hz?

Also, what is the difference between FBQ2496 and DCX2496? Can both of them do room EQ (i.e. measure room > fix all annoying sound bumps)?

Thanks!


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## brucek (Apr 11, 2006)

> FBQ2496 and DCX2496? Can both of them do room EQ (i.e. measure room > fix all


No, the FBQ does not do auto room EQ. The DCX is a Loudspeaker Management System, where the FBQ is an equalizer only.

The FBQ cannot set a filter below 20Hz and does not support shelving filters that might be needed for the sealed sub.

I think the DEQ2496 would be closer to what you're looking for.

brucek


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## fackamato (Sep 19, 2007)

brucek said:


> No, the FBQ does not do auto room EQ. The DCX is a Loudspeaker Management System, where the FBQ is an equalizer only.
> 
> The FBQ cannot set a filter below 20Hz and does not support shelving filters that might be needed for the sealed sub.
> 
> ...


Hm okay.

What are shelving filters?

Also, I see that REW doesn't support the DEQ2496. That doesn't mean I can't use it, right? "Just" add the filters manually..

Thanks,

Mathias


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## brucek (Apr 11, 2006)

> What are shelving filters?


Different from a standard filter (which would rise to a peak or trough equally with a certain bandwidth), a shelving filter rises from a specified frequency and continues to rise to a certain level. So, you could specify a hinge point at 40Hz and rise up 10dB to 20Hz (like a shelf was placed between the two points). To create a psuedo shelf using standard filters is difficult. 



> I see that REW doesn't support the DEQ2496. That doesn't mean I can't use it, right? "Just" add the filters manually..


That's correct, as long as you specify an equalizer in REW that matches the same Q and bandwidth formula as the DEQ2496.

brucek


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## fackamato (Sep 19, 2007)

brucek said:


> Different from a standard filter (which would rise to a peak or trough equally with a certain bandwidth), a shelving filter rises from a specified frequency and continues to rise to a certain level. So, you could specify a hinge point at 40Hz and rise up 10dB to 20Hz (like a shelf was placed between the two points). To create a psuedo shelf using standard filters is difficult.


Thanks for the great explanation!



brucek said:


> That's correct, as long as you specify an equalizer in REW that matches the same Q and bandwidth formula as the DEQ2496.
> 
> brucek


Okay, is this "known" already? I mean, there must be some people using the DEQ2496 and REW! (I admit, I haven't really looked in to it yet since I'm a few months head of myself here)


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## brucek (Apr 11, 2006)

> there must be some people using the DEQ2496 and REW


I believe you select the FBQ2496 as the equalizer type in REW, and then the filters will be valid, although I think the DEQ has a low limit of 1/10th of an octave and the FBQ goes down to 1/60th of an octave (not that you would use a filter that narrow).

brucek


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

> Which EQ can go down as low as 10 or 5Hz?


The Symetrix 551E (mono) and 552E (stereo) parametrics go to 10 Hz. Nice discontinued equalizer from a company that specializes in quality audio equipment for the broadcasting industry. That means it's not something the pro audio guys are lusting after, so you can get them dirt cheap when they appear on eBay. I just picked up one for under $150 for my band (I'm going to check it out in my system before I turn it over to them). Note that it has a non-defeatable low cut filter that can't be set lower than 6 Hz...



> What are shelving filters?


A picture is worth a thousand words...







​

Regards,
Wayne


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## spreston (May 21, 2008)

Wayne:

Thanks for the highly descriptive images of shelving filters! Won't think twice about definition ever again.


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