# do i need a bfd



## bdw8306 (Aug 30, 2010)

Are there any advantages over using a bfd over a manual eq other than faster?


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

Welcome to the Forum, bdw!

Your question is a bit confusing. Any equalizer is “manual,” even the BFD. If you’re talking about using it with REW and having REW send filter settings to the BFD automatically, then yes, “faster” is the primary advantage of the BFD over some others. However, REW only offers this feature for equalizing low frequencies, not full range. So if full range is you’re intending to equalize, the automatic feature won’t benefit you.

Regards,
Wayne


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## grn1969c10 (Sep 18, 2008)

The BFD is a parametric equalizer. It allows you to manually set the center frequency, width and gain of each filter. It has fine adjustments in 1/60th octave increments. This can add some versatility as compared to a 15 or 31 band graphic equalizer which has filters at fixed 2/3 or 1/3 octave centers and fixed bandwidths.

There is a certain convenience to having REW automatically set the filters using a midi cable, however, manually setting them is rather quick. It's a set-it and forget-it kind of thing. Once you are happy with the results you don't change them again. (Unless your like some of us who have to re-tweak everything once every six months, even if it was just fine. It can be a fun and rewarding addiction.)

Matt


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## parsley (Mar 23, 2007)

"Are there any advantages over using a bfd over a manual eq other than faster? "

If you mean "can the BFD set up / run a PA system so that it can play at the highest volume before feeding back through the mics?", in my experience : not very well. It seemed to allow increasing feedback whines to just continue. Maybe the levels were low at its point in the chain, so a threshold wasn't triggered, but I'd like a system to stop things when they're quiet and beginning not when they're painful.

ps this was the FBQ2496

and from google, others have had more success with live PA use, so maybe I should try it again


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

parsley said:


> "Are there any advantages over using a bfd over a manual eq other than faster? "
> 
> If you mean "can the BFD set up / run a PA system so that it can play at the highest volume before feeding back through the mics?", in my experience : not very well.


What he meant was having REW automatically program filters into the BFD instead of loading the filter parameters manually. This is a home theater forum, we don’t have feedback problems. 

Regards,
Wayne


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## ghost rider (Dec 29, 2010)

Glad I found this forum!:T

Looking at the waveform from a frequency sweep I micd. Does it look like I could get a lot of positive results from a BFD set up by REW?

Judging from a google search they are pretty cheap. I did see that some people have a hum is this a 60hz ground loop hum? I have had problems with ground loops and recently I completely disconnected every componet and reconnected one thing at a time and was able to isolate the hum at one of the amps dedicated to one of my subs. My setup is very clean now so I'm reluctant to connect anything between my subs.

I'm also looking into room treatments I started a thread over there.


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

> Looking at the waveform from a frequency sweep I micd. Does it look like I could get a lot of positive results from a BFD set up by REW?


You can’t really tell from a waveform. It would be better to do a frequency response graph. That said, virtually all subwoofers can benefit from parametric EQ. 

Regards,
Wayne


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## ghost rider (Dec 29, 2010)

Thanks Wayne,

I was thinking I have a good start on the equipment I need but need to verify that and ask some questions.

I can use my Echo Mona audio card that has XLR and phantom power mic inputs. It’s in my 2nd HTPC but via PCMIA interface I can move it easily. I have a Shure VP 88 microphone but think I will need the EMC8000.

My first question of many to come is, I’m using the 5.1 analog input and I have only one .1 sub out can I split it before the BFD and then the BFD can control it separately?


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## ghost rider (Dec 29, 2010)

Wayne A. Pflughaupt said:


> You can’t really tell from a waveform. It would be better to do a frequency response graph. That said, virtually all subwoofers can benefit from parametric EQ.
> 
> Regards,
> Wayne


I kind of figured as much but just looking at it sure looks like I have some big cancelation going on suggesting to me that room treatment will help. So I looking into that also.


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

ghost rider said:


> My first question of many to come is, I’m using the 5.1 analog input and I have only one .1 sub out can I split it before the BFD and then the BFD can control it separately?


Not following you on that, but maybe one of the connection schemes shown here will tell you what you need to know:

REW Cabling and Connection Basics

Regards,
Wayne


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## ghost rider (Dec 29, 2010)

yes I saw that where it says "in stereo mode only" I only have a mono out.


I may have out to much thought into that but with that in mind could BFD control each sub differently if I split the signal before BFD.


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

You could do that, but it’s typically best to EQ all subs as a single entity, not separately. The experience of most people trying to EQ subs separately is that you get them each measuring good, but when you then combine them response goes down the tubes.

What kind of subs are you using? Another no-no is using mismatched subs.

Regards,
Wayne


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## ghost rider (Dec 29, 2010)

Wayne A. Pflughaupt said:


> .
> 
> What kind of subs are you using? Another no-no is using mismatched subs.
> 
> ...


Perhaps the worst kind of all, DIY subs. They are 15in JBL drivers in a 7 cu ft box with a tuned port, They stand on end with a down firing speaker, in the cabinet. They are powered by 2 Adcom 555 mono bridged. I have no crossovers or gains. Actually they sound pretty good and I will not be changing them soon. As a matter of fact I may need to reengineer my complete system to get it right but I’m not going to do that either. I can do that on the next house. For now room treatment and BFD may be as far as I want to go.

I posted some pictures in this thread be sure to look at the PDF file room layout to see recomended treatments http://www.hometheatershack.com/for...y-considering-room-treatments.html#post333628


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

What are you talking about, “the worst kind?” Everyone knows all the best subs are DIY!  It’s good to see you’re using matching subs, though. Just EQ them as a single and you'll get good results. :T

Regards,
Wayne


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## ghost rider (Dec 29, 2010)

Wayne A. Pflughaupt said:


> What are you talking about, “the worst kind?” Everyone knows all the best subs are DIY!  It’s good to see you’re using matching subs, though. Just EQ them as a single and you'll get good results. :T
> 
> Regards,
> Wayne


Thanks Wayne,

So all the hardware I need is a BFD, ecm8000 (my Shure VP88 won't do it?) a midi to USB cable and my Echo Mona should work as the mic preamp


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## ghost rider (Dec 29, 2010)

I ordered the stuff. I guess that's all I will need. I have a 20 year old RS SPL meter and 2 1/4 inch to rca cables


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

ghost rider said:


> So all the hardware I need is a BFD, ecm8000 (my Shure VP88 won't do it?) a midi to USB cable and my Echo Mona should work as the mic preamp


If you’re only interested in measuring your subwoofers, all you need is the SPL meter, not the ECM mic.

Regards,
Wayne


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## ghost rider (Dec 29, 2010)

Wayne A. Pflughaupt said:


> If you’re only interested in measuring your subwoofers, all you need is the SPL meter, not the ECM mic.
> 
> Regards,
> Wayne


In the bigger picture if I want to measure the room's responce as to assist me in room treatment application, I need the mic.


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

Perhaps not - we recently had a thread on this very topic. See here.

Regards,
Wayne


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## ghost rider (Dec 29, 2010)

ok if I don't need it that was a misunderstanding I had but if it's something a tweaker would want to have

so if my Mona will work as the preamp is it a better way to go or is the fact that neither are calibrated that I’m kinda winging it.


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## ghost rider (Dec 29, 2010)

sorry for all the questions. So if I use the generic calibration file I can run a test today, before I get the BFD.

If I have this right I disconnect the R&L output from my sound card. Using a y adapter I sum the R output into both R&L input on my preamp. I then take the left output from SC and run it into the left input on the SC. That’s the part that’s fuzzy. I keep connected that way only for the first part of the test and then disconnect the loop and run the remaining parts of measurement.


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## grn1969c10 (Sep 18, 2008)

Deleted,

(I missed P.2 of the thread!)

Matt


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