BFD, How important is this unit?

[P-Dub]

Just wonering, how imporant is a Behringer Feedback Destroyer?

Is it the same thing as the ART 351 Equalizer?

How do you know if you need one?




Paul

There are three kinds of people in this world; those that can count, and those that can't.

[brucek]

Paul,

I think bass equalization is very important. In fact, I probably wouldn't have a sub if I couldn't EQ it. I'm really not a fan of listening to "one note bass". When you use a sub in the home, given the usual dimensions and parallel surfaces, there will be standing waves that will upset the nice flat response of your subwoofer (almost always). These axial modes will usually create several peaks that can easily be 10dB - 15dB louder than the surrounding frequencies. When you calibrate the level of your sub, these peaks are what you use, leaving the other frequencies too low. The result is a one note bass that doesn't sound unlike that boom boom type of sound you hear coming from those cars that have the big systems.

Enter the parametric equalizer. The reason a parametric is necessary as opposed to the analog fixed 1/3 octave type with ISO spacing you referred to (Art 351), is that you need to be able to adjust not only the gain of certain frequencies, but you need control over the bandwidth and center frequency of a filter to effectively remove a peak. The BFD is a very effective and inexpensive device to use on bass EQ.

How do you know if you need an equalizer? Well, it's simple. You take a low frequency response of your sub by itself in your room and graph the result.

First you require a good test disk, or preferably, you can just make your own if you have a CDr on your computer.
Download this FREE tone generator listed below and save the tones in five second files and burn them on a CDR.

http://www.nch.com.au/action/index.html

Scroll down to Freeware and click on TONE GENERATOR and download......

It's really only necessary to use sixth octave tones.

Do a response check from 16Hz to 160Hz at 1/6 octaves, at about a level of 85dB to 90dB SPL taken with a Radio Shack SPL meter at your normal prime listening position using a source of the CD playing 5 second sine wave tones tones.. Be sure to use the correction constants for the Radio Shack meter for 1/6 octaves.

It's a good idea to use the information and Excel graphing tool on Sonnie Parkers site (listed below - he's an HTG member) which has the graphs all pre-done including compensation correction for the SPL meter: The site is dedicated to a BFD equalizer, but the information is still very useful if you're just doing a response on your system. You should read all the stuff on this site first.

http://www.snapbug.ws/bfd.htm

Once you've taken the response of your sub (with the other speakers shut off so they won't interact), you'll likely be able to see several peaks and dips. Dips are usually left alone, because they're difficult to remove and throwing more power at them just eats up headroom. You can try and lift a dip and see if it responds, but if not, leave it alone.
Peaks are easy to remove with the equalizer. Once you've flattened your peaks, you'll likely want to turn the wholesale level of your sub back up (since the peak is gone) and you'll realize a much more smooth and even sounding bass......

brucek

[Sonnie Parker]

Great response as usual Ken.

Paul, unless you have the perfect room and perfect setup (basically an anechoic chamber), you will probably find you need a BFD. I read where lot's of people talk about critical music listening and they don't even have their subs equalized for their listening position. Things that make ya go hmmmm! Bass is very critical in movie soundtracks as well. If it's not right then you could be missing something or getting too much of another.

Those test tones are on the BFD website as well. You can pick the ones you want. They are 10 seconds with fade in and fade out the first and last second to eliminate the pops.

You can set up several different presets (filtered response curves) with the BFD as well. One for music and one for movies.






SONNIE

Cedar Creek Cinema

DVD Collection

BFD Comprehensive Setup Guide

[P-Dub]

Wow, thanks for the response guys. I'll have to do some more reading and setting up. I think I'll try and take some measurments with my existing sub and see what I get. I've got all the parts, CDRW, SPL meter, Excel.

So where's a good place to find one of these units?




Paul

There are three kinds of people in this world; those that can count, and those that can't.

[Sonnie Parker]

I ordered mine from http://www.lentines.com/pa/equbeh.stm for $130 but there are other places on the net. I believe this is about the going price.






SONNIE

Cedar Creek Cinema

DVD Collection

BFD Comprehensive Setup Guide

[skiierguy]

i currently have a mint BFD for sale on another forum; here's the link:

*** SOLD ***

please feel free to email me with questions. thanks!

[David Meek]

Hi Tom, welcome to the forum. Where in Texas are you? Down my way?




David - HTGuide flunky
Our "Theater"
Our DVDs on DVD Tracker

[Lex]

Skierguy, welcome to the forum! In the future, I ask that if you have something to sell here, that you post it in our Pawn Shop. We have a silent rule to not allow links to sales on other forums. While I am sure you meant no harm, that's nothing more than advertising. That's why we have our own buy and sell area for members.

Thanks,
Lex