# On BFD 1124- Any way of adjusting below 20hz?



## tdamocles (Sep 23, 2006)

Just wondering if there was a way to adjust below 20hz or is that limited by the BFD?


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## Guest (Dec 2, 2006)

I think if you boost below 20Hz you can easily destroy your sub. You also don't need to lower freq. below 20Hz since subs don't have much output that low...


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## brucek (Apr 11, 2006)

> Just wondering if there was a way to adjust below 20hz or is that limited by the BFD?


The BFD doesn't limit the signal below 20Hz. It doesn't have any filters below 20Hz though. Many IB subs extend easily to 10hz, but equalization is a problem.

brucek


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## Otto (May 18, 2006)

When EQing my IB, I boosted wide-band at 20 Hz, and then cut narrow band at 20 Hz and just above. This will work if you want to address a general hump/dip at <20 Hz. It's somewhat trial and error, but I was able to get decent results. What kind of sub are you using?


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## brucek (Apr 11, 2006)

> When EQing my IB, I boosted wide-band at 20 Hz


But how much did you boost at 20Hz to get any effect at 10hz for example. Quite a bit I would guess.

brucek


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## Otto (May 18, 2006)

Yeah, it was quite a bit. IIRC, I also kicked up my amp's gain quite a bit and then did a lot of cutting to hit my target.


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## Sonnie (Apr 11, 2006)

I think this is one advantage of the BFD FBQ2496... where you can use a bandwidth of 120/60 at 20Hz. Of course you'd have to add a shelf filter at the appropriate frequency to eliminate any unnecessary boosting above 20Hz that the 120/60 filter will create.


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## brucek (Apr 11, 2006)

> Of course you'd have to add a shelf filter


Does the FBQ have shelf filters?

The 1124 also allows up to 120/60 BW....

brucek


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## Guest (Dec 2, 2006)

"bandwidth of 120/60 at 20Hz"

could any of you guys explain what this means?


IB subwoofer? Do you mean something like this:
http://white.hometheatertalk.com/tips/ib.htm
?


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## brucek (Apr 11, 2006)

> bandwidth of 120/60


This is a filter width. You can set filters as low as 1/60th of an octave wide, up to 120/60 wide, which would be two octaves.



> IB subwoofer? Do you mean something like this


Yep. See our DIY subwoofer section for some discussion from members that have them..

brucek


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## Sonnie (Apr 11, 2006)

Maybe I missed something somewhere... seems like there was something about the FBQ that made it more preferable than the DSP for IB's and for some reason I was thinking it was the BW.

I don't think it has a shelf filter, but you'd need something similar to what you've done in the past with the one filter stuck way up around 300Hz or so... maybe lower for this... I guess depending on what happens with the filter at 20Hz. It would be interesting to see some graphs on one.


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## tdamocles (Sep 23, 2006)

Sonnie said:


> Maybe I missed something somewhere... seems like there was something about the FBQ that made it more preferable than the DSP for IB's and for some reason I was thinking it was the BW.
> 
> I don't think it has a shelf filter, but you'd need something similar to what you've done in the past with the one filter stuck way up around 300Hz or so... maybe lower for this... I guess depending on what happens with the filter at 20Hz. It would be interesting to see some graphs on one.


If there are any more abbreviations my head is going to explode!


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## Chrisbee (Apr 20, 2006)

I'm using a 120/60 +16dB boost @ 20Hz with my IB using the 1124P. Several other filters at 10Hz steps 30Hz, 40Hz etc bring the inevitable hump above 20Hz back down to the target curve leaving the sub-20Hz boost almost untouched. I probably have an easy 100+dB (uncorrected RS SPL meter) capability at 10Hz if I was brave enough to try.

I see no excess cone movement suggestive of overdriving my AE IB15 drivers on any programme material tried so far. I take no responsibility for others destroying their subs (IB or not) in trying this extreme BFD filter setting. My IB has always needed to be driven hard to get any cone movement at all despite the very high SPLs I am getting.

Before and after graphs appear in my sig using the latest soft-look RS SPL meter and the REW correction file.


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## Sonnie (Apr 11, 2006)

tdamocles said:


> If there are any more abbreviations my head is going to explode!


Sorry bout that... the FBQ is the newer model BFD, the FBQ2496. The DSP is the older but more popular BFD, the DSP1124P. IB is Infinite Baffle subwoofer. BW is bandwidth as referred to in the BFD units.


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## tdamocles (Sep 23, 2006)

Sonnie said:


> Sorry bout that... the FBQ is the newer model BFD, the FBQ2496. The DSP is the older but more popular BFD, the DSP1124P. IB is Infinite Baffle subwoofer. BW is bandwidth as referred to in the BFD units.


I thought it was kinda funny...I had a few chillies and happened to read that thread.


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