Behringer Feedback Destroyer - Initial Results

[whmacs]

Hi All,
After a bit of reading on room / subwoofer interactions, I picked up a Behringer Feedback Destroyer Pro from a local Music shop on friday. Yesterday I spent a couple of hours setting up the BDF with my two subs. You can view the results in this graph. As you can see, I had three large humps, while not a 'house curve' yet (a bit more tweaking is required), the BFD has greatly smoothed out the response of my two subs. While the low end slam is still there, the big difference is the increased clarity in the mids to highs as the humps around 56 and 100Hz were muffling the higher frequencies. I never realised this until I heard the difference. You can take the BDF in or out of circuit with the press of a button, so its easy to compare the sound before and after. I'm a newbie with the BDF, but so far the results are very promising. I'll introduce a 'house curve' by raisng the frequencies (reducing my current cuts) < 40Hz when I get some quite time (i.e. wife and kids aren't around). While the BDF has a bit of a learning curve, this guide is invaluable. I'd really appreciate if any any of the more experienced BFD users had any suggestions on how I could improve my graph further.

cheers,
Stephen

[K.K.]

I am also a BFD newbie and was really pleased and surprised with the results that I can get from such an affordable device, relative to the costs we pay for other hi fi and HT hardwares.

I only run the BFD through my subwoofers and I could not get a very smooth curve but the BFD has definitely helped in integrating my subs to my main front speakers. The overhanging boominess has been removed successfully by the BFD. I mainly use the RoomEQ software because it can send the settings to the BFD directly through midi and I can play around interactively with the curves in the software. I don't think I will ever get a 'perfect' curve due to the fact that I am not doing any correction to my main speakers. So I am less fussy but if there's anyone willing to give more guidance, I am all ears.

Cheers

[whmacs]

Well,
I got a chance to do a bit more tweaking and added a 'house curve' through a different preset on the BDF. I now have a flat response on preset 4 and a 'house curve' on preset 5. Both these graphs are subs only, no mains. You can also view the combined response of both subs and mains here. All I can say is Wow! While a flat response increase clarity, it lacked a bit of low end authority, adding a 'house curve' has returned that authority with a vengence. Watching LOTR and Star Wars II, I was grinning from ear to ear.
I really can't recommend a BDF highly enough for anyone wanting to get the most out of their sub(s).

cheers,
Stephen

[Andrew Pratt]

You might want to boost the house curve even more steeply then it is now and see how you like that. Here's my curve. As you can see my room has some serious nulls and peaks to smooth out.

[Nick M]

I always tell people the BFD is one of the best values in HT.

Nice FR! :T

[whmacs]

Hi Andrew and Nick
Andrew, you certainly had some big valleys to deal with there! How did you end up getting rid of them, did you get the BFD to cut down to the lowest point then raise the overall sub volume, or did you add some +db gains into the BFD?
Now that I have a house curve dialed in I'll experiment with the angle of the slope, but I must say it sounds bloody good now, real 'hit you in the chest' material

I also have my subs mounted in a cabinet (10" sub on left, 15" sub on right), so the BFD is a silver bullet for people like me who can't move their subs around the room (mainly due to WAF)

cheers,
Stephen

[K.K.]

Well,
I got a chance to do a bit more tweaking and added a 'house curve' through a different preset on the BDF. I now have a flat response on preset 4 and a 'house curve' on preset 5. Both these graphs are subs only, no mains. You can also view the combined response of both subs and mains here. All I can say is Wow! While a flat response increase clarity, it lacked a bit of low end authority, adding a 'house curve' has returned that authority with a vengence.

It looks like you had to to a lot of boosting at 71hz+ and Andrew's at 22hz-. How much gain did both of you have to dial in? My understanding of gain is that it shouldn't be more than +6db at most. What are the others' views?

Cheers

[whmacs]

Hi K.K,
I gave it a 10db boost at 71Hz. I think that it is more of an issue at lower frequencies. Looking at the snapbug site, he boosted +10db at 50Hz. The way I figure it the higher the frequency the safer it is to boost. I've also watched the clipping meter on the BDF and I've come nowhere near clipping. 2/3 is the highest I've had the meter during movie watching.

cheers,
Stephen

[RobP]

Hey Guys, Just for a reference, here is a example of the curve used in movie theatres, this comes from the DTS processor manual. In some theatres its not uncommon to see adjustments made more than 6db, but it should really be no more than 3db per octave.

[K.K.]

The way I figure it the higher the frequency the safer it is to boost. I've also watched the clipping meter on the BDF and I've come nowhere near clipping. 2/3 is the highest I've had the meter during movie watching.

Stephen

I can't remember well but I thought high boosting will cause a strain on the sub woofer's amplifier and potentially cause clipping at the sub rather than at the BFD. Maybe I misunderstood that. But since it appears that you don't play them loud enough to clip the BFD, it's probably fine :roll:

Cheers

[whmacs]

Stephen

I can't remember well but I thought high boosting will cause a strain on the sub woofer's amplifier and potentially cause clipping at the sub rather than at the BFD. Maybe I misunderstood that. But since it appears that you don't play them loud enough to clip the BFD, it's probably fine :roll:

Cheers

Hi K.K.,
That probably makes more sense than what I said, I'm still not overly concerned, as I calibrated the BFD at my normal listening level so a +10db is still only making the subs hit 90-95db which isn't that much. Saying that, I will keep an ear on the sub's performance over the next few weeks.

cheers,
Stephen

[Andrew Pratt]

It largely depends on the room. A true null won't budge no matter how much power you try to boost it. My room actually responded fairly well to some increase in the nulls so I added what I thought was safe and then cut the peaks accordingly then adjusted the over all levels.

[whmacs]

It largely depends on the room. A true null won't budge no matter how much power you try to boost it. My room actually responded fairly well to some increase in the nulls so I added what I thought was safe and then cut the peaks accordingly then adjusted the over all levels.

Thats a good point Andrew, when I added a +10 boost, I got a 10db increase in sound level. Considering that I had to boost around the 71-80Hz mark, it may have something to do with the phase between the main speakers and subs and not an actual room null. Changing the phase setting on the subs could possibly remove the need for such a large boost.

cheers,
Stephen

[Andrew Pratt]

Right the first thing we need to do once you've plotted your room is to try fixing the problem by adjusting phase and moveing the sub as much as allowed...once you've got it as good as you can then and only then should you move on to the BFD.

[Sonnie Parker]

Stephen... I can't get your pages/links to open... is it me or have you lost the links? I'd like to see your graphs. I'll host them for you if you'll e-mail them to me. Just let me know if I can help.

It's reasonably common to get a dip around that 80hz range if you have your x-over point set there. A 10db boost shouldn't hurt a thing as long as it sounds okay.

Andrew has certainly got you headed in the right direction... I'd definitely try to do as much with moving the sub as possible before diggin' into the BFD settings.

[whmacs]

Stephen... I can't get your pages/links to open... is it me or have you lost the links? I'd like to see your graphs. I'll host them for you if you'll e-mail them to me. Just let me know if I can help.

It's reasonably common to get a dip around that 80hz range if you have your x-over point set there. A 10db boost shouldn't hurt a thing as long as it sounds okay.

Andrew has certainly got you headed in the right direction... I'd definitely try to do as much with moving the sub as possible before diggin' into the BFD settings.

Hi Sonnie,
First off I would like to say thanks for creating such a great BFD setup guide. I could not have set up my BFD without it! Sorry the links are broken, I've been putting together a bit of web site on my HT and I've had to move things around a bit. My graphs are now located here
I've also fixed up the broken links at the top of this thread. Thanks!

cheers,
Stephen

[Sonnie Parker]

Nice page Stephen... looks like you got your response all lined up really good.

[ajpoe]

I have made some more adjustments to my subs using my recently acquired BFD. I originally charted my response with that spreadsheet, I have since tested it with RoomEQ Wizard. I'd also like to thank Sonny for his amazing guide page and spreadsheet.

It looks like my filters are doing the job... do you think the peak in the lower region is too high? This sweep is with the subs only.



Also, here is a graph of the the fronts with the subs in stereo 10 Hz - 20 KHz:


Here is an image of all speakers running in 5.1 DPLII Cinema mode 10 Hz - 20 KHz:


If anyone see's any problems or something I should address, please let me know.

BTW, RoomEQ Wizard is a very sweet program!

[brucek]

do you think the peak in the lower region is too high?

Nope. I think if you look at the subs response from 20Hz and higher, it's quite good. Ignore the graph less than 20Hz. Not much info there anyway. The portion from 20Hz to 50Hz satifies what many would call a house curve. I'm sure it sounds fine. :T

brucek

[Sonnie Parker]

Nuff said! ;x(

[Rolyasm]

I am going to be purchasing a Destroyer soon, but I have noticed several different models. There is an 1100, 1124 and a 2234 or something like that. Are they all the same, because they look the same? If they are different, which one should I be getting so I can follow the tips listed on this forum? Thanks
Roly

[ajpoe]

The 1124P is the one that pretty much everyone has been using. You can get one for around $100 shipped. The 2234 is a new model I believe and quite a bit more expensive. I don't know if the added benefits are worth it, but if just using it as a pEQ, I highly doubt it as the 1124 has worked fine for everyone so far. Maybe some of the pros can add more details.

[Sonnie Parker]

I don't think the 1100 is available anymore... it appears the only difference between the 1124 and 2234 for sub eq'ing will be 40 filters instead of 24 and the $200 price tag. The operation should be basically the same. I don't think any improvement in quality is much good since we are using it on the lower frequencies, but I cannot affirm that.