# Multiple BFQ2496 patched together?



## Andysu (May 8, 2008)

Is it possible to use the BFQ2496 in groups patched in loop configuration to control each frequency band though to the cut-off point on the crossover? Would using the narrow filters of the Q result in ultra flat response? 

1 FBQ2496
Left 20 channels 
*1 *20Hz 
*2 *21Hz 
*3* 22Hz 
*4 *23Hz 
*5 *24Hz 
*6 *25Hz 
*7* 26Hz 
*8 *27Hz 
*9 *28Hz 
*10* 29Hz 
*11 *30Hz 
*12 *31Hz 
*13 *32Hz 
*14 *33Hz 
*15 *34Hz 
*16 *35Hz 
*17 *36Hz 
*18 *37Hz 
*19 *38Hz 
*20* 39Hz

Right 20 channels 
*1* 40Hz 
*2* 41Hz 
*3* 42Hz 
*4 *43Hz 
*5* 44Hz 
*6* 45Hz 
*7* 46Hz 
*8 *47Hz 
*9 *48Hz 
*10 *49Hz 
*11 *50Hz 
*12* 51Hz 
*13 *52Hz 
*14 *53Hz 
*15* 54Hz 
*16 *55Hz 
*17* 56 Hz 
*18* 57Hz 
*19* 58Hz 
*20* 59Hz

2 FBQ2496
Left 20 channels 
*1* 60Hz 
*2* 61Hz 
*3 *62Hz 
*4* 63Hz 
*5* 64Hz 
*6* 65Hz 
*7* 66Hz 
*8 *67Hz 
*9 *68Hz 
*10 *69Hz 
*11* 70Hz 
*12* 71Hz 
*13* 72Hz 
*14* 73Hz 
*15* 74Hz 
*16* 75Hz 
*17* 76Hz 
*18* 77Hz 
*19* 78Hz
*20* 79Hz

Right 20 channels 
*1* 80Hz 
*2* 81Hz 
*3* 82Hz 
*4 *83Hz 
*5* 84Hz 
*6 *85Hz 
*7* 86Hz 
*8* 87Hz 
*9 *88Hz 
*10 *89Hz 
*11 *90Hz 
*12* 91Hz 
*13* 92Hz 
*14 *93Hz 
*15 *94Hz 
*16 *95Hz 
*17 *96Hz 
*18 *97Hz 
*19* 98Hz 
*20* 99Hz


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## brucek (Apr 11, 2006)

I assume you mean FBQ2496?

And why would you want to do this? A parametric equalizers purpose is generally to tame peaks caused by the modal resonances in a room. Usually, a few carefully matched filters can tame any subwoofers response. There is little need or advantage to using 80 filters to obtain an ultra flat response that would only be valid at one finite spot in a room. A few inches away and it wouldn't be an ultra flat response any more.

brucek


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

Hi Andy,

There are at least a few problems with this approach. 

For one, the number of whole-number frequencies doubles with each octave. Notice that you only have twenty proposed filters between 20-40 Hz, but forty between 40-80 Hz. So to keep things linear, you'd need half-frequency steps below 40 Hz, and quarter-frequency steps above 80 Hz. The FBQ2496 can't do increments like that.

For another, it's impossible for an equalizer to have a filter set so tight that it only affects a single frequency. Every filter "bleeds" over to adjacent frequencies, and the more it is boosted or cut, the wider it "bleeds."

Also, it's generally considered undesirable to over-filter a sound system.

Fortunately, it isn't necessary to to achieve per-frequency linearity to get excellent sounding bass. In fact, a number of people who frequent this Forum found out the hard way that their bass sounded better when they cut back on the number of filters they were using, even if response didn't look quite as "pretty."

Suggested reading:

On Mminimal EQ and a Hard Knee House Curve

Regards,
Wayne


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## Andysu (May 8, 2008)

brucek said:


> I assume you mean FBQ2496?
> 
> And why would you want to do this? A parametric equalizers purpose is generally to tame peaks caused by the modal resonances in a room. Usually, a few carefully matched filters can tame any subwoofers response. There is little need or advantage to using 80 filters to obtain an ultra flat response that would only be valid at one finite spot in a room. A few inches away and it wouldn't be an ultra flat response any more.
> 
> brucek


LOL I always get the letters mixed up always. Yes FBQ2496. 

One spot in the room now that does seem limited oh well it’s just a thought and since these units sale cheaper than biscuits at Harrods,:bigsmile: it’s worth a try to explore its potential, to see how far it can be taken.

Thanks anyway.


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## Andysu (May 8, 2008)

Evening Wayne 

I guess you, posted just about the last time I, did. Okay so it’s not valid way to do it okay what else can it be used foe besides doing two subs per channel etc, etc.

I remember reading about adjacent filters on poor EQ’s that crosstalk badly so is the BFQ2496 a poor-mans EQ I don’t think it is its performance is great, but I’d like to explore it further.


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

> okay what else can it be used foe besides doing two subs per channel etc, etc.


Feedback control in a PA system. :bigsmile:



> I remember reading about adjacent filters on poor EQ’s that crosstalk badly...


Whatever you saw was probably talking about graphic equalizers, where a slider (filter) boosted or cut also raises or lowers the gain of the frequency center of adjacent sliders (although in a lesser amount), even if they are not moved at all. This isn't a problem with parametric EQs, where a problem like that (in the unlikely event it would even occur) could literally be adjusted away with the bandwidth control.

Regards,
Wayne


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