View Full Version : My BFD experience.

Eddie Horton
03-08-2005, 03:31 PM
Well, last Sunday was the day I finally broke down and ordered a Behringer Feedback Destroyer to EQ my sub. According to UPS, it should be here when I get home from work tomorrow. So far, I've burned test tones to CD from 18Hz-120Hz, and created a chart to plot the measurements for before and after EQ. I've found a guy from Alabama (the best state) who posted a comprehensive setup guide at www.snapbug.ws Seems like everything one would need to get started. The only thing that I still need is a better correction chart for the Rat Shack SPL meter. I found one, but it skips frequencies too much, and you'd have to guess what values to add for the other frequencies. Anyone know where to get a better one? On the dude's web site, he says there is a compensation chart for Excel that automatically corrects when you enter values, but I don't have Excel on my home computer so...... Anyway, that's where I'm at right now. Just wanted to get this thread started so I could share my experience with the BFD. More to come............

03-08-2005, 04:26 PM
Here you go ... this is from the excel spreadsheet:

03-08-2005, 04:52 PM
You can download a free Excel compatible program here. I highly recommend this product.


If you use Sonny's excel spreadsheet @ snapbug, the accompanying graph has a built in dip at 111hz. Don't try to compensate for this dip unless it's reflected in your actual numbers.


Eddie Horton
03-09-2005, 05:40 AM
Thanks, guys. I plan on getting started when I get home from work today.

Lee Bailey
03-09-2005, 07:49 AM
Even though it's not free, RivesAudio makes a test CD that has a set of tones already modifed with the corrections built in for the RS meter.

Eddie Horton
03-09-2005, 02:39 PM
Got home from work today and the wifey had signed for the package. Everything arrived from PE in great shape. Opened the box, and wow, I almost freaked out at the size of the owners manual until I realized that it was translated into about 30 different languages. Right now, I'm printing the setup guide from snapbug's site......should have already done that. As soon as the printer stops, I'm gonna get after it and see what kind of damage I can do. Later.

Eddie Horton
03-09-2005, 05:02 PM
This is going to take longer than I thought (like everything else). Got it hooked up, set the input level, and started taking measurements. In a word, my room is f'ed. Here's what I got so far. These are corrected measurements.
18Hz - 75dB
20Hz - 74.5dB
22Hz - 74.5dB
25Hz - 74dB
28Hz - 78dB
31.5Hz - 83dB
36Hz - 91.5dB
40Hz - 93.5dB
45Hz - 91dB
50Hz - 90.5dB
56Hz - 91.5dB
63Hz - 83.5dB
That's what I have so far.....a NASTY hump that starts right after 25Hz and doesn't start going down until after 56Hz. This is going to be fun, but I'm done for the night.

03-09-2005, 06:37 PM
One big hump is actually one of the better situations to be in. You might even be able to fix it with a single wide PEQ point. The bigger pains are lots of fluctuations, particularly dips (since its better to lower humps than raise dips). I think you'll be in good shape.

BTW: There was an interesting conversation recently on AV123's forum about whether it was better to flatten bass or allow it to be louder at lower frequencies to compensate for the fact that people don't hear lower frequencies as well. In the end, it seems to depend how things were recorded/engineered/mixed. When I get around to EQing my setup, I may try one flat and one sloped and see how it sounds.

Eddie Horton
03-10-2005, 03:19 AM
You're talking about the "house curve", right Brad? Depending on how my plot looks all the way out to 140Hz, I may go for one of those. Also, it's encouraging to know that my FR isn't as bad as it first appears. It makes sense, though. One big hump would be easier to fix than several sharp peaks and troughs. You lose head room fast when trying to boost a dip.

03-10-2005, 06:46 AM
You lose head room fast when trying to boost a dip. I once read somewhere that you are not supposed to put any gain on a null. Instead you are supposed to cut the rest of the frequencies to match that dip and then turn the gain up on the sub.

03-10-2005, 09:39 AM
I once read somewhere that you are not supposed to put any gain on a null. Instead you are supposed to cut the rest of the frequencies to match that dip and then turn the gain up on the sub.

Since cuts are less problematic than boosts, this is a good approach. I think the general rule of thumb is no more than a 2-3db boost.

03-10-2005, 10:06 AM
I just had an hour with my BFD. There is no end to the tweaking you can do with this thing. If you like to tinker, this is a great toy. Every time I change one filter it changes everything else so I removed all filters except one and I think this is the best so far. Gotta get to the office so I'll try to fill in later.


Eddie Horton
03-10-2005, 01:48 PM
A little off topic, but my wife and I got our pre-approval for our mortgage today, so it looks like anything I accomplish with the BFD will just have to be re-done when the house is finished being built. I don't care, though. I'm finally going to have a DEDICATED ROOM!!!!!!! Life is good.

Eddie Horton
03-10-2005, 04:39 PM
Played around with the BFD some more. Set a couple of filters to experiment with the fine frequency adjustment, bandwidth, and gain features. The more I play with this thing, the more I realize that it will be worth it but is going to take longer than I first thought. No more messing around for an hour in the evenings. This Saturday is now earmarked for BFD setup time.

03-10-2005, 04:44 PM
You're just procrastinating. :D

Eddie Horton
03-10-2005, 06:04 PM
I do procrastinate sometimes. Wanna see the top 10 reasons why?

03-10-2005, 06:09 PM
I do procrastinate sometimes. Wanna see the top 10 reasons why?
1. ... :D

Eddie Horton
03-13-2005, 12:15 PM
After a few hours and 3 filters, I am basically within 4dB from 16Hz to 100Hz. There is a 6dB hump at about 140Hz, but that is due to room interactions with my Ascends above the crossover point of the sub. Not much I can do about that. I'm still gonna tweak it a little more, but this is a HUGE improvement from where I first started. For 99 bucks, this is a great investment.

03-13-2005, 01:39 PM
Nice work Eddie, been following your thread with great interest. Do you have any thoughts on how the BFD has effected your music and movies sound quality?

Eddie Horton
03-13-2005, 03:22 PM
Johnny, I'm glad you asked because I was just about to post my thoughts on this. When I first got my system, music was a distant second to HT, but lately some things have come together which has made me reconsider my already large CD collection and my ever growing DVD-A and SACD stack. First would have to be the weather. Here in Alabama it's been beautiful the past few weeks save a few rain storms. When the weather's nice, it's great to open all the windows, put on some music and just chill out. Second would be my wife's job change. She's been an RN for 15 years doing regular hospital type work, but has recently taken a position as a research nurse working M-F 8 to 5 like a normal person, so we now have time to chill out on the weekends together. We both love music, so we have been listening to a lot these past few weekends. Last but not least has been this BFD revelation that I've begun to fully experience this weekend. I can't say enough about what a difference this thing has made with music. Before, my sub was calibrated to the loudest frequency for the most part, so anything that fell in one of the nulls was basically getting left out. I've been listening to my Fleetwood Mac and Diana Krall DVD-A's today and the bass is superb. Every note now flows out of my VTF-3MkII with authority!! I haven't really put a good movie through it since getting it right, but I will tonight. Honestly, this thing has made my system come alive from 100Hz down. I don't have the vocabulary or technical knowledge to describe it, but now every bass note is easily discernable. My HSU is a great sub, but now I know how a room can make a good sub sound less than perfect.

03-14-2005, 02:34 PM
Hey Eddie...by the time you move into the new house, maybe Hsu will be ready with this technology....

Eddie Horton
03-14-2005, 03:15 PM
Yeah, it'll be just another step in the ever present upgrade cycle.

Eddie Horton
03-14-2005, 07:15 PM
Ok, after six filters and a lot of tweaking, here's where I stand. These levels have been corrected for the Rat Shack meter, so they are accurate.
16Hz - 79.5
20Hz - 79
22Hz - 78.5
25Hz - 81
28Hz - 79
31.5Hz - 78
36Hz - 80.5
40Hz - 80.5
45Hz - 79
50Hz - 80.5
56Hz - 81.5
63Hz - 81.5
71Hz - 80.5
80Hz - 79.5
89Hz - 80.5
100Hz - 81
These measurements are with my mains playing and crossed at 80Hz. Talk about a seamless integration. I may bump the sub up to where it's about 3-4dB hot. I'm used to the way it was, so now it sounds too quiet even though it's even with the mains. I may also experiment with a "house curve" with a rising response from about 36Hz down to 16Hz and see what happens. There's a part of me that doesn't want to mess with it any further for fear that things could only go bad from here. It's almost perfect where it is, so I may just bump up the overall volume about 4dB and call it quits until we move.

03-14-2005, 07:17 PM
Wow....that is great.

Come out to California and you can do the same for my setup!

03-14-2005, 08:33 PM
That looks really good. I've thought about doing this a number of times, but I've been afraid I wouldn't get good results (i.e. I wouldn't do it right...) Wasting money isn't high on my list of activities, but results like that would definitely be worth that much and more.

03-14-2005, 09:01 PM
Doh, I wasn't paying attention and created a new thread with Curtis' link in the other area - oh well.

It looks like you have an excellent new response.

Eddie Horton
03-15-2005, 01:59 PM
For me, the best way was the way Sonnie Parker and Wayne Pflughaupt suggested. Start two or three broad filters and then come back with a couple more to tweak things. If you start with a bunch of really narrow filters, it just doesn't seem to ever want to get right. That was my experience, anyway.

03-15-2005, 04:28 PM
Way to go Eddie...now you've got a flat sub frequency response...to match the flat response of your Ascends. Nice job!


03-24-2005, 11:38 AM
Hey Eddie.......

We tried to get another Ascend customer from Outlaw's forum, we shall see! ;)

Any new results with the BFD? I'm planning on picking one up in the next month or so and could use any advice/tips you can give.

Eddie Horton
03-24-2005, 01:12 PM
Yeah, that guy that's considering the Ascends or Digm' Studio 60's lives in the same town I do....weird, huh? The only new thing I've done with whole BFD thing is to bump up the sub level 4dB hotter than the mains. This seems to have done the trick and now it doesn't seem like the sub is too quiet. Also, I was under the impression that my Yamaha HTR-5790 would only store one set of channel levels regardless of what input was being used. I was wrong. It will store one set for the multi-channel inputs and one for everything else. So now, movies and TV are properly calibrated with the sub 4dB hot and my SACD's and DVD-A's are propery set up with the sub kicked up 10dB to compensate for the fact that the LFE channel on hi-rez discs is encoded way too low most of the time. I still haven't experimented with a house curve yet, and will more than likely wait till after the move to do anything else. I have only one major gripe with the BFD, and that is all the damn bright LED's. My sub is in the left rear corner of my room, and the BFD stays on top of it out of the way. I couldn't stand having it in the equipment rack. Too bright!!! Oh, well........for 99 bucks I can't really complain.

03-24-2005, 01:23 PM
I've compared my 340's with Studio 60's......it was myself and three other guys, one of them was auditioning speakers. He ended up getting 340's.

03-24-2005, 01:33 PM
I thought there was a way to turn the LEDS off? I'll have to look at the manual online.

I too was wondering about using just one or two filters instead of a bunch of narrow ones. I guess having the thing in the system and tinkering is the best way to go, but I don't have a lot of free time to experiment.

Has the improvement in response made the low end more defined/articulate?

After hearing an Onix UFW-10, which has a single band PEQ, I was convinced of the benefits of EQ'ing my sub.

Eddie Horton
03-24-2005, 02:06 PM
It is 110% more defined and articulate. People throw the term "night and day difference" around all the time in the audio/video world, but this is for real. I guess how much of a difference will depend on how much the room interactions were messing up the FR to begin with. In my case, though, the difference has been huge.

03-24-2005, 02:16 PM
Eddie...how much time in total did you spend on setting the BFD up? From opennng the box, reading, to flat FR.

03-24-2005, 03:02 PM
"In my case, though, the difference has been huge."

Same here. My livingroom is my HT and there was only one place where I had one major spike but with lots of not so major up and downs. All the other locations I tried had at least two major spikes as well as lots of not so major up and downs.
I been able to get +/- 2db from 37hz to 120hz using the BFD. I'm doing this with the $125. Dayton sub. I can imagine what can be accomplished with a Hsu.


Eddie Horton
03-24-2005, 03:09 PM
Curtis, I put in several hours from opening the box to flat FR. Once you get the hang of it though, it starts to go fast. When I did my first filter, I played around with the frequency, fine adjustment, bandwidth, and cut/boost so I could see what they actually did. Once I got the hang of it, it was easy to make an educated guess about what frequency, bandwidth, and cut/boost to use. On another note, a guy that I met on the Outlaw Forum that lives in my town just left after coming by to check out my Ascend/Hsu system. Needless to say, he was blown away and said that he will be purchasing some Ascends when he gets around to upgrading his speakers. He just got a big DLP and Denon 2900, so he's well on his way to a great setup. Really nice guy, too.

03-28-2005, 10:29 AM
OK Eddie and David....I just picked up a BFD off of eBay. Not a great deal, saved me about $20.

I probably won't get a chance to mess around with it for a couple of weekends.

Eddie Horton
03-29-2005, 03:55 AM
Keep us updated, Curtis.

03-29-2005, 08:15 AM
this is great info. looking forward to more results, or even trying one for myself.

03-31-2005, 11:02 PM
My BFD was delivered today....looks brand new, but without the manual, and I can't seem to download one from the Behringer site...it is asking for a login when I select the manual.....

Anyways, I just plugged in the power and messed with the buttons...it looks pretty easy. Eventhough I won't really be able to dial it in until later next week, I will start reading the snapbug site now so it will all sink in.

Also thinking about getting TrueRTA or ETF.....maybe even a nicer microphone...but for now, I think the RS meter will suffice.

Eddie Horton
04-01-2005, 05:30 AM
Curtis, if you read the snapbug setup guide, you really don't need the Behringer manual. After reading a thread over at AVS, I'm with you about wanting to try TrueRTA. I'd need to buy a cheap used laptop and the rest of the gear, but it would be cool to be able to run tones through it and make changes with the BFD on the fly and actually see the results as you do it. Just when I think this hobby has gotten as expensive as it's gonna get for me, something else catches my eye.

04-01-2005, 09:48 AM
I don't think I've ever looked at the Behringer manual. Curtis, I can fax you a copy if you like.


04-01-2005, 09:57 AM
Thanks Guys!

I just got an email back from Behringer saying they fixed their site.....I'll try it later. If I have a problem, David, I will let you know.

04-03-2005, 10:14 PM
OK...making some progress...just ordered another sub cable from BlueJeans. I'll stop at Radio Shack some time this week to get the 1/4" to RCA adapters.

04-04-2005, 05:17 AM
You guys are dangerously persuasive... I went out and found myself a BFD on ebay as well (got it for $49.99), but I bought the older model, the DSP 1100P. Does anyone know what the differences are between the two units? At least one of the online guides to equalizating subs references this unit, so I'm assuming it will do what needs doing to tame my Dayton sub...

04-04-2005, 12:16 PM
I do not know the differences, but I think it should do the job.

04-04-2005, 12:26 PM
I retook my readings at lunch(yes, I'm able to go home at lunch!), and am getting different readings.

don't know if I misunderstood what I was reading from the meter or what....maybe some doors were closed before that were left open this time....I dunno?

I am getting the following(setting 80db REF. at 1000hz):

68db @ 20Hz

72db @ 25Hz

79db @ 31.5Hz

81db @ 40Hz

73db @ 50Hz

83db @ 63Hz

78db @ 80hz(Crossover point)

Since my sub is rated to 24Hz, I'll ignore the 20Hz figure. My thought is that since I calibrated the system with Avia to 85db, I had to turn the subs gain down to achieve that level due to the peak at 63Hz. That peak is +11db over the 25Hz point. The dip at 50Hz is 10db lower than the 63Hz peak. A second peak at 40Hz is 9db higher than the 25Hz point, with 31.5Hz being 7db higher than 25Hz. I'll use 25Hz as my REFERENCE point and cut down to this. I will probably have to raise the gain on the sub when I finish to bring the sound levels back to system ref.

I can't explain why my readings were so different from the first set I took, but I will definitely do some more before I get the BFD in the system.

Any thoughts, based on the numbers above, as to how many filters, at what frequencies and "Q" settings I should start off with?


04-04-2005, 03:03 PM
I would want more data points than just these few. There's too much going on here to tweak based on just this info. I'm anal so I use every freq between 20 and 120hz. Something interesting going on around 50hz for sure.


Eddie Horton
04-04-2005, 05:04 PM
My listening room has 2 doors coming into it. If I take measurements with them open and then close them, it make a dramatic difference in the FR. Also, take measurements with 1/6 octave sine waves from 16 to around 160Hz. When learning how this thing works, set one filter and then change different parameters on purpose just to see what effect it will have. This, IMO, is the easiest way to get the hang of it. It will cut down on the number of filters you end up using because you will know how to maximize each one.

04-04-2005, 05:27 PM
hmmm.....I have two closeable doors into my livingroom. When I am listening to music, both doors are usually open. When watching movies, it depends are the circumstances as to which doors are open.

The BFD can store different curves right?

04-04-2005, 07:43 PM
The BFD can store different curves right?

Yes. I only use one but many have posted using one for movies and one for music. There are more but I haven't read about anyone using more than two.


Nicholas Mosher
04-04-2005, 07:57 PM
Yeah, I believe you can store up to 10 curves if you want that many...

Party mode
Quiet mode

04-04-2005, 08:55 PM
Now I am wondering again if it would be worth while to get some measurement software like ETF or TrueRTA to watch changes in realtime rather than single measurements and plotting.

Nicholas Mosher
04-04-2005, 09:01 PM
Then you need the software, fancy microphone, tripod for said microphone, hours for learning the new software, etc...

Just read Sonny's guide...

After you set one filter you don't even need the guide anymore, its so easy.

EDIT: I just use one curve for everything. Set it to sound good with music, and movies will sound equally fantastic! ;)

04-04-2005, 09:08 PM
Now I am wondering again if it would be worth while to get some measurement software like ETF or TrueRTA to watch changes in realtime rather than single measurements and plotting.

Haha - I thought I just convinced you NOT to buy that. :) For what it's worth, you can stop by and borrow mine. :D

Here is a thread with some pointers on free audio software: http://forum.av123.com/showthread.php?s=&threadid=7809 I just downloaded a few of them to try out (I already had the free version of TrueRTA). I have to double-check, but the trial version of ETF might be enough to do basic measurements as well. Even with free software, an ECM8000 mic and pre-amp will run about $100.

I agree with the earlier comment to use at least 1/6 octave tones. I downloaded a good set of 1/12 octave tones that someone on AV123 posted. That is what I used for my recent measurements using the RS SPL meter. I also agree that you should measure well beyond the crossover point (see my measurement post). You may or may not be able to fix problems in that range, but it will certainly show any phase mismatch with the mains.

04-04-2005, 09:12 PM
Both software companies say the RS meter used as a mic is good enough for subwoofer EQing, I have a tripod, and I am told the software is not that difficult to learn.

Then again...it is another $100-$150 for the software...and I would need some more cables.

04-04-2005, 09:19 PM
Thanks Brad....

If the weather is not good on Saturday.....it is going to be my project.

I emailed one of the engineers at Hsu, and he also said that anything less than 1/6 octave is not good for correcting low frequency room anamolies...and could actually hurt response.

The realtime aquisition is what draws me to use the software and my laptop.

04-04-2005, 09:55 PM

I haven't tried the RS meter as an input for the software. I like how ETF can use a loopback in the second channel to remove the soundcard from the equation.

As I said, you might be able to get away with using the trial version of ETF for measurements. Basically, it limits you to only two measurements per session (it can get annoying pretty quickly), but I think the functions are mostly (if not all) there. I like that ETF takes about 5 seconds to run a measurement, so it's quick and easy to do repeat measurements while you tweak. It isn't as intuititve as TrueRTA, but I could do some quick instructions. TrueRTA is pretty easy to use, but you have to pay $100 to get the 1/12 octave resolution. I should do some tests with ETF using the ECM8000 and comparing it to the RS meter also using ETF (my other comparisons were with the RS meter using the manual test-tone method).

04-04-2005, 10:51 PM
basicly...it is $100 for TrueRTA or $150 for ETF, $100 for mic-preamp/mic, and possibly an external soundcard for the laptop...and cables.

I'll think about it some more.

04-05-2005, 05:13 AM
The two discs I have with tones have the same freq. steps....1/3 octave....so the next step after 80hz is 100hz, then 125Hz. I will redo the measurements and run them to 160Hz.

If I am using an 80Hz crossover, what effect will the BFD have on freq's above that? It will be in the sub path, not the mains.

I will be getting the BFD tomorrow.

Eddie Horton
04-05-2005, 05:42 AM
As the crossover is not a brick wall on the speaker side or the sub side, the sub will still be contributing to the FR above the crossover point, but with decreasing output depending on the slope of the crossover.

04-05-2005, 05:49 AM
If I am using an 80Hz crossover, what effect will the BFD have on freq's above that? It will be in the sub path, not the mains.

The BFD can be used at almost any freq. I found that there is no substitution for experimenting.


04-05-2005, 05:59 AM
Thanks guys! I won't have a lot of "Tweak time", so I'm looking for the quick and simple. I realize I will have to experiment, but it never hurts to seek advice from those who have "been there, done that!"

Now, I should download the Snapbug instructions to get a grip on the setup process!

04-05-2005, 06:15 AM

The link posted by jimsfield here: http://forum.av123.com/showthread.php?s=&threadid=7719 is a set of 1/12 octave mp3s that can be burned to CD. They are 6 sec each IIRC and are slightly faded in and out to prevent clicking from sudden volume changes. I just made a list of the frequencies that I used in Excel and printed out a sheet for writing down the frequencies as it played. It goes pretty smoothly except for pausing when you need to switch the range on the SPL meter.

The BFD Excel file uses 1/6 octave measurement, so I just charted it in a new spreadsheet. To check the corrected values, I interpolated corrections for the additional data points. If there is interest, I could clean up my spreadsheet and post it.

04-05-2005, 06:21 AM
BTW: Your crossover is likely 24db/octave (possibly 12db/octave) which means that if your sub is at 85db at 80Hz, it will still be putting out 61db at 160Hz. This is why the phase is so important, since the sub can destructively interfere with your main speakers for quite a while.

04-05-2005, 07:16 AM

My subs X-over max's out at 150Hz......that is where I have it set. My Outlaw 1050 is set at 80Hz X-over. Not sure of the slopes, I think the sub has either 18db/octave or 24. It is not a Linkwitz-Riley, so 18 may be right.

The guy selling me the BFD(Ajax) burned the test CD's for me(the Hsu and the Rives discs). I don't have a burner. I'll see if he can burn one from the link you posted.

I like snapbug's idea of measuring the sub without the mains running. I could see how high the frequencies are being reproduced above the cutoff.

I drew up my own chart in AutoCAD. I draw a Spline through the points, which automatically curves/smooths out the line.

I looked at the UFW-10 manual online to see how they setup the filter on it, and they are only using 1/3 octave measurements. The Rives test CD has a set of tones which are made specifically to correct the Radio Shack meter's readings without needing to manually interpolate them.

04-05-2005, 08:23 AM

While also measuring the sub without the mains is useful, you should definitely measure them with the mains to ensure you aren't getting destructive interference because of your phase setting. Ideally, you should measure with the mains using different phase settings to see which works best (see my measurement thread for my two phase graphs).

04-05-2005, 08:46 AM
Oh lordy......

what am I getting myself into?!!! :D

04-05-2005, 09:05 AM
Oh lordy......

what am I getting myself into?!!! :D

And do at least 1/6 octave!!

I think I am going to go the ETF route, and get as close to "right" as I can without pulling my hair out.

04-05-2005, 09:56 AM
I went home at lunch and set up another measure session!

I had the HVAC off and closed the door behind the seating position. I sat behind the loveseat in a chair so I could read the meter. Meter was on a mini tripod, atop stacked couch pillows, angled at approx. 45 degrees up.

I set the 25Hz tone to read 80db on the meter(corrected).

Here go's;

20Hz = 80db(Surprised!!)

25Hz = 80db

31.5Hz = 85Hz

40Hz = 86db

50Hz = 80db

63Hz = 90db

80Hz = 80db

100Hz = 95db

125Hz = 71db(Huh?)

160Hz = 88db

200Hz = 87db

That's with phase at 0 degrees(0-180), playing in two channel mode. I listen to music mainly in stereo, so I left it in stereo for the test.

The biggest shock was having 20Hz the same as 25Hz. Must be the room. I wonder how far below 20 it will go? My sub's manual only rates it to 24Hz.
Actually, 20Hz was a tick stronger than 25Hz(maybe 1/4db).

Now what?!!

Nicholas Mosher
04-05-2005, 10:04 AM
The spike at 60Hz is induced by the height of the room from what I've been told. Knocking that 60Hz peak down will really clean up music and intense bass scenes.

I also have a rogue null up around 120Hz. Mine is from 105Hz to 115Hz, and is un-fixable in my case... :mad:

Eddie Horton
04-05-2005, 10:26 AM
Mag, that doesn't look too bad. You have about 3 humps and a null to work on. I ended up with 3 "main" filters and then came back with 3 more to smooth things out to my liking. It looks like you could do the same thing, or even use less. Not bad at all. Just out of curiosity, is seems like everyone who has a hump at around 60Hz (which I did) also has a null around 120 (which I also did). If you have a hump at a certain frequency, will you always have a null at one octave higher? I need to study up on my room acoustics a little more.

04-05-2005, 11:50 AM

that was my thought as well regarding filters. Ajax(Jack), from whom I'm buying the BFD, has burned a copy of the RealTraps test tracks to disc for me. These are in 1hz steps from 10-300hz, grouped in tracks of ten....track 1 is 10-19hz, track 2 is 20-29hz, etc., each tone lasting ten seconds, each track lasting 100 seconds. It will get real interesting when I run these!

04-05-2005, 11:55 AM
Having nulls at multiples of frequencies can be either be because of the same room dimension (it produces standing waves at the multiples) or because another room dimension happens to be about double another one (e.g. 8ft ceiling and 16ft length). You can compute the likely room modes using one of many online calculators like this one:http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html

My best advice for you Mag, do 1/6 (or better) octave tones if you can get your hands on them. Then follow some of the advice here, kill your humps at ~63 and ~100. The 125 will be hard to fight with sub EQ since the crossover is dropping the output down quite a bit already there.

04-06-2005, 06:43 AM
2 quick questions while I await delivery on my BFD.

1) My sub is corner loaded across the room from my gear (only real option for it), and connected via a Parts Express sub cable that runs into a standard RCA cabe that was pre-installed in a wall plate when we moved in. I know it's FAR from ideal, but re-wiring it would be a complete nightmare. Up to this point, I haven't had any problems (that I know of), but I wondering whether its more advisable to introduce the BFD before or after the standard RCA cable (or does it make a difference?).

2) The BFD is 2-channel, but I only need to run one cable (and buy one 1/4"-to-RCA connector) if I'm only equalizing one sub, correct?

04-06-2005, 07:04 AM
You put the BFD inline with the cable going to the sub, so you are, in effect, putting a break in that cable.

You need two 1/4" to RCA adapters.....one going to the input of the BFD, and one on the output of the BFD. From the output, you add another sub cable(RCA) to your sub.

04-06-2005, 07:57 AM
Thanks, Mag Neato. I actually understood all that (except the part about the need for 2 adapters -- thanks for that info)... what I was really asking was whether it was more advisable to insert the BFD before or after the weakest link in the chain, which in this case is a non-specialized, run-of-the-mill RCA cable (as opposed to a shielded, sub cable).

My setup currently goes like this.

Receiver sub out > 12-15 feet of standard RCA under the floor and in wall > wall plate > parts express sub cable > sub

So the BFD could go in my component rack, in which case it go before the standard RCA, or atop the sub, in which case it would be after. Probably doesn't matter, but I thought I'd check with those who know more than me first...

04-06-2005, 08:38 AM
I'm getting my unit at lunch today........30 minutes!

I am using a 20 ft. SoundStream stereo cable. It's connected to a "Y" from the 1050's LFE out and runs to the subs L/R inputs. I'll need to do some rewiring to accomodate the BFD. It will be worth it to have more defined and articulate bass.

04-06-2005, 08:50 AM
the lights on the BFD are pretty bright....any way to dim them?

04-06-2005, 09:09 AM
the lights on the BFD are pretty bright....any way to dim them?

I think eletrical tape is the standard practice (seriously). If you wanted to mod a BFD, you might be able to add resistors inline with the LEDs, but that assumes there is room and they aren't surface mount.

04-06-2005, 10:10 AM
Electrical tape?LOL!

I don't think Behringer had home theater in mind while designing it.

Got mine at lunch.......now the fun starts! :eek:

04-06-2005, 10:40 AM
I've got electrical tape over the "4" but I can live with the two red LED's. You can't tell the tape is there unless you open the cabinet and look right at it.


04-06-2005, 11:02 AM
If you wanted to reduce the brightness but still be able to see the lights, you could put smoked plexiglass over the faceplate.

Eddie Horton
04-06-2005, 11:56 AM
Smoked plexiglass isn't a bad idea. I put some rubber pads with adhesive on one side on the bottom of the BFD so it wouldn't dance and rattle, then placed it on top of my sub. The sub sits in the left rear corner of the room, so it's mostly out of sight. Still, two people so far thought it was a second cable box because of the big bright "4" on the display. When I explain that it's a parametric EQ for my sub, they usually respond with either "Oh, OK" or "Damn, you're a geek."

04-06-2005, 12:30 PM
Smoked plexiglass isn't a bad idea. I put some rubber pads with adhesive on one side on the bottom of the BFD so it wouldn't dance and rattle, then placed it on top of my sub. The sub sits in the left rear corner of the room, so it's mostly out of sight. Still, two people so far thought it was a second cable box because of the big bright "4" on the display. When I explain that it's a parametric EQ for my sub, they usually respond with either "Oh, OK" or "Damn, you're a geek."
My sub is also partially out of site in the front left corner. I think I will go Eddie's route.

Right now I have it in my rack while I was playing with it. Last night I realized how bright it is.

Also..the memory on it is non-volatile right? Meaning I can cut all power to it and it will still retain the settings. I want to remotely control the power to it via some switched outlets on my power conditioner. Otherwise, I will just leave it on all the time.

Nicholas Mosher
04-06-2005, 01:20 PM
When I explain that it's a parametric EQ for my sub, they usually respond with either "Oh, OK" or "Damn, you're a geek."That sounds awfully familiar around my setup... :rolleyes:

EDIT: Until they hear it that is... (and I didn't even have the PB10 that long!)

04-07-2005, 11:43 AM
OK...so I am going to geek out a little more with my EQing.

In communicating with more people "in the know", they are advising me to take measurements and EQ in 1Hz measurements to really pinpoint and EQ the problem frequencies with my sub.

So I will probably purchase and download ETF(which does at least 1/12th octave), purchase the adapter and cables, and try to take some measurements this evening. If I am successful learning the software, I will start another thread.

Other than that, I am going to watch "Flight of the Phoenix" tonight.

04-07-2005, 12:30 PM

if you need 1hz steps, go to www.realtraps.com

they have a free download complete with a logorythmic chart. They go from 10-300hz and are 10 seconds each. They stress that you do not absolutely have to do the meter corrections to get a meaningful result. Jack burned me a copy, but I haven't run it yet.

04-07-2005, 12:47 PM
Thanks Ed,

Another nice thing about these software programs is that they have tone generators.

I just downloaded ETF....doesn't look too hard.

Nicholas Mosher
04-07-2005, 12:49 PM

I use this free tone generator.
Any frequency, duration, etc. Even saves as wav format for direct burn to cd.

04-07-2005, 12:58 PM
Man........I gotta get a newer PC with a burner!! :mad:

04-07-2005, 02:35 PM
I just downloaded ETF....doesn't look too hard.

You're brighter than me. It took me a while to get the hang of ETF and the different graphs and adjusting the gate timing, etc. It's nice to be able to do the quick sweeps and I think the trial version will cover the needs of a lot of people. I just grabbed the trial version of Praxis and will see how it compares.

04-07-2005, 03:29 PM
I just said it didn't look too hard......I didn't say I knew how to use it yet. :D

04-08-2005, 07:54 AM
I checked out the ETF site..........is that really a buck-fifty to download?


I'll stick with my trusty RS meter, thank you very much!

Mr. Fabrikant has graciously offered his expert advice as I travel down the sub measurement/EQ road. Now that's what I call customer service! :)

04-08-2005, 08:10 AM
Well....I couldn't get the trial version of ETF to work for me last night on my laptop, so I didn't buy it.

I did get the trial version of TrueRTA to work, but it can't any better than full octave resolution until you pay for it....so I will probably go that route, and it is less expensive than ETF.

04-08-2005, 08:16 AM

I can try and walk you through ETF if you send me a note explaining where you had problems.

Another option would be to try something like Praxis. I think the trial version has more features than the trial version of ETF, but I haven't had time to play with it. RightMark RMAA is another option. It's totally free, but again I haven't had time to play with it and see if it is any good. I'm hoping to play with both this weekend.

04-08-2005, 08:26 AM
What about the BFD software available that simulates the effects of filter settings? I think it is a free download.

04-12-2005, 03:42 PM
Apologies for the cross-post, but I seriously doubt anyone would bother to read my "630 Just Died" thread, now that it has been resolved, so I copied this here... Hope that's OK...

I don't know about the 635, but many receivers don't EQ the sub output. Even if they did, most receivers only have 1, maybe 2 EQ bands in the sub frequency range.

The receiver's EQ function is different from what the BFD does. It would be my guess that the BFD would make the receiver's EQ work even better. No low freq peaks to compensate for.

I somehow missed your response on this David. You raise some very interesting possibilities re: integrating the BFD and the 635, and have me hoping I didn't just waste $$ on a BFD. I just slogged through about half of a 29-page thread re: the capabilities of the H/K 635 on AVS, and while I was extremely disappointed to learn that the 635 does not offer bass management or EQ on its 8 hi-rez analog inputs (a feature included on the 630), I was surprised to hear that its low frequency digital EQ was the best on the market in this price range. I still need to do some research regarding how many bands it offers, etc. but the input of at least one poster suggested the BFD would be superfluous.

"My SVS had a huge hump in my room at about +20 dB around 40-50 Hz. Now its +or- 4 dB from 120Hz to 20Hz. Amazing."

So, I guess I'm a little confused as to how I go about testing the BFD's usefulness in my situation. Would I configure the BFD before applying any of the 635's EZset/EQ tests? And furthermore, the 635 apparently comes with an accurate mic. Can I assume I could use that instead of a Radio Shack SPL (which I have yet to purchase)?

04-14-2005, 01:48 PM
Based on some reponses I received here and elsewhere, it sounds like using the BFD on top of the HK 635's EQ may add some additional benefit and flexibility (add a room curve, if desired, multiple settings for movies/music, etc.) Curious if you guys are aware of and/or have tried this free Room EQ software:

Room EQ Wizard

Still in beta testing, but I think it offers many of the same functions as the others, including support for the BFD. You can also simply use it to massage and graph your data, without running the mic/meter directly through it. Anyway, once I get my Rat Shack meter and the 635, I'll probably be posting graphs and peppering you guys with questions. Hope that's cool...

04-20-2005, 07:07 AM
I have the BFD hooked up, running in bypass mode. I ran more tones with the whole system running and got some new numbers.


Any thoughts/opinions? I know the numbers look pretty good. In fact, they look good enough to Dave F. that he suggests NOT changing a thing!

What do y'all think?

04-20-2005, 10:00 AM
I agree. I wouldn't touch it. Congrats. I wasn't near as lucky.


04-20-2005, 10:19 AM
Anyone interested in a BFD? :rolleyes:

04-20-2005, 10:20 AM
Yeah.....I agree with the two Davids.

04-20-2005, 10:23 AM
Anyone interested in a BFD? :rolleyes:I'm going to be adding some bass traps to my room over the next couple of weeks. If I still have peaks then I might get one. Right now I have a couple of nulls that I'm hoping to kill with the bass traps.

If you post it for sale on audiogon or something like that it will probably sell right away.

Eddie Horton
04-20-2005, 03:28 PM
Ed, you are lucky. I had a couple of huge peaks and a nasty dip or two if I remember correctly. If you are super anal about it, you could tweak a little here and there, but it ain't bad the way it is.

04-26-2005, 07:28 AM
Well, I set up three filters per a suggestion from a semi-experienced BFD tweaker. So far, the sound seems to be cleaner, with better definition, giving percussive sounds a bit more snap. It seems like I can turn up the sub level now without suffering from any boom. I like what it has done so far.

Per Craigsub's advice, I will be adding a fourth filter to give the lowest octave, centered at 28hz, a 6db boost. He had the same sub in the 90's and said I could get good EQ'd response to 25hz.

So far, I like the effect it is having. I will post more after I add the 4th filter and take some new measurements.

04-27-2005, 01:51 PM
Okay....I added the fourth filter and took spl measurements.

18hz @ 63db
20hz @ 67.5db
23hz @ 78.5db
26hz @ 87db
29hz @ 92db
32hz @ 93db
36hz @ 92.5db
39hz @ 91.5db
42hz @ 90db
45hz @ 89.5db
51hz @ 88.5db
57hz @ 88.5db
63hz @ 88.5db
72hz @ 91.5db
78hz @ 92.5db
84hz@ 76.5db
90hz @ 89db
102hz @ 87db
114hz @ 76.5db
126hz @ 79.5db
160hz @ 80db

Pretty good results for a small investment. +/-3db from 26 to 80hz for a ten year old sub ain't too shabby!

05-19-2005, 05:06 PM
I read through this entire thread and now I'm completely exhausted!

Can you just pay somebody to come in and EQ your stuff? My DIY
interest kind of stalls at this level. I just want it to sound good:-)

Eddie Horton
05-20-2005, 06:06 AM
My wife and I would love to see Phoenix........hint hint.

05-20-2005, 07:13 AM
Can you just pay somebody to come in and EQ your stuff? My DIY
interest kind of stalls at this level. I just want it to sound good:-)

There are EQ's that are much simpler than the BFD. They just cost quite a bit more currently. I expect prices to fall as more companies get into it.


05-20-2005, 07:35 AM
I, too, was a little intimidated at first. Once you have the measurements done using test tones and the RS meter, you've done the hard part.

Setting up the BFD was easy once you learn it's input methodology. Plus, I posted my measurements on the Axiom forum and got my filter suggestions from a couple of forum members(Craigsub for one). I did not even have to think about where to start! :D

05-20-2005, 10:56 AM
And now that the free Room EQ Wizard (http://homepage.ntlworld.com/john.mulcahy/roomeq/index.html) software is available, even a technical idiot like me can do it ;-)

05-31-2005, 04:33 PM
I found a great thread on AVS that is dedicated to Room EQ Wizard, and the author of the application participates.