Can u do this with a BFD ? (1 Viewer)

[John-Tompkins]

...It is a TWO channel eq right ? ..can you eq one sub on one channel and then eq another sub with a different set of parameters on the other channel and use them both at once ?. One channel will be getting an lfe signal and the other channel will be getting everything from 80 hz and down from the main l/r channel.

Im wanting to eq my main l/r speaker's woofer's (wired in paralell as one speaker) on one channel of the bfd and then the lfe sub (svs) on the other channel of the bfd...I was gonna get two bfd's but thought maybe I could do it all from one bfd.Any help would be apreciated.
Do I need one or two bfd's?

 

[Brian Fellmeth]

You can do this with one, two separate signal paths with 12 filters each to use.

 

[John-Tompkins]

Thanks much !

 

[GrahamT]

Yep, one BFD will do. Check out this site if you haven't seen it before. It helped me out a lot.
http://www.snapbug.ws/bfd.htm

 

[Chris Tsutsui]

That's not a bad idea... but if you wire your L/R Mains woofer channels together, what about the stereo bass that comes from them. (not that it's probably a big thing to lose)

But why not let the receiver crossover the Mains with the LFE, and leave out the BFD from the Main's signal path? I guess if there are some peaks in the freq. response that your mains play then "ideally" I'd get 2 bfds.

One BFD for your mains, and another BFD for the sub. This way you can EQ each main channel and maintain the stereo bass. Then use your 2nd BFD to EQ your LF sub(s).

Of course... you'd have to justify $100+ for that small difference.. heh

 

[ChuckRG]

Another question. I have an audio buddy who is not particularly technically saavy and would be interested in the Auto EQ function of the Berhinger.

Does the auto correct function of the Berhinger 24/96 create a correction using the parametric EQ function or the graphic EQ function (or both?)

 

[John-Tompkins]

My situation is a bit different and lends itself well to just one bfd I think. I have NHT T5 speakers for my main l/r channels. The T5 speaker consist of an M5 satellite and a B5 bass module and they are connected via an X1 controller ( active crossover with phase, adjustable cross point for low and high pass, boudary eg, volume control etc.) NHT did this for maximum flexibilty and it works great for room integration for a full range speaker.

The B5 bass module is only 12 ohms, so NHT reccomends that you run both b5 modules in paralell for a 6 ohm load ( remember that below 80 hz isnt locatable bass anyway)..Ive tried it both ways and couldnt tell any differences whatsoever.

Also I dont like to run the lfe svs's when I listen to sacd/dvd-audio or redbook, rather just run my T5s full range.So what I can do is:
Run main l/r full range from pre-pro to X-1 controller.
Send low pass (80 hz and below) to the BFD for eq.
Send 80 hz and above straight to my amps..The bfd never touches anything 80 hz and above.
Then just eq my lfe svs subs on the other bfd channel
Everything should be good to go..for music AND movies

 

[Greg Bright]

Do your SVSs' have high pass outputs (not speaker level)? If so that would lend itself to yet another way of hooking up your BFD, as I have done.

 

[Wayne A. Pflughaupt]

Sounds like you have a handle on the connection scheme, John.

You’ll just have to keep in mind that equalizing multiple low frequency sources – by that I mean those that are placed at various places around the room – is difficult. You may well find that once you EQ the B5 and SVS separately, and then fire them all up together, that it’s a whole new ball game.

EQing both B5s with a single equalizer should be fine if you have symmetrical placement in the room, but if you don’t it may be a problem. Take my situation, for instance, I have one main a few feet from a corner, and the other next to an open doorway. Naturally, the former emphasizes the bass more so than the latter. In that situation you couldn’t expect a single equalizer to do the job.

Since you don’t use the subs for music listening, that will be to your advantage. This way you can pay the most attention to getting the B5s accurate. If you loose some accuracy when the SVS is kicked in for movies, it won’t be catastrophic. Most low frequency material there is merely booms and rumble from explosions and things.

Regards,
Wayne A. Pflughaupt

 

[John-Tompkins]

Luckily (or unluckily really ) I have a 14X14X9 room which isnt good from a standing waves point of view..But it does make all my speakers have a rather symmetrical placement. My main L/R are both at equal distance from the back and side walls and since I have a projector Im able to place the b5's woofers inward pointed at each other.

 

[Wayne A. Pflughaupt]

That’s good – you should have no problem equalizing the two B5s with a single equalizer.

Regards,
Wayne A. Pflughaupt

 

[John-Tompkins]

So would it be best to do the eq-ing with both the lfe subs and b5's active ? ..I guess this may be best for movies as this would be the only circumstance that would have both lfe and b5s going.
If I eq them seperately I may in fact be making my bass for movies worse and not better ?
I should add that my lfe svs subs are in the same corner as the right b5 woofer ( maybe only 1~2 ft or so away)

 

[Wayne A. Pflughaupt]

In your situation, since music and the B5’s are what’s most important to you, EQ them and the SVS subs separately. EQ both systems with the M5 L/R mains on - this will allow for the EQ to make some compensations for phase issues caused by the crossovers (typically these show up as response deviations in the first octave or so above and below the crossover frequency). Don’t forget to dial in an appropriate house curve.

At that point, when you add them both together, if new response deviations show up that weren’t there before, try do deal with them as best you can with the SVS EQ channel only (leave the B5 channel alone). You may not be able to get “perfect” combined response this way, but it does insure that you’ll be getting the best from the B5s when you use them alone.

After you’re satisfied with your combined response curves, you can adjust the respective gain levels of each system as accordingly.

Regards,
Wayne A. Pflughaupt

 

[John-Tompkins]

Thanks Wayne that makes sense.

I would like to keep the svs's in one corner but Ive noticed by running sine waves that I get the flatest response having them split up with one 1/3 from the front wall and the other 1/3 from the back wall (it kinda evens out a fairly large 50hz valley I have...What it be dum to keep them in the corner (where I really want them) and just eq them...or should I split them up as to start with a better curve before eq-ing ?

Side question for anybody, How do you take the excel graphs and put them in your posting here on htf ?

 

[Greg Bright]

Russ Herschelmann of Ultimate AV is against corner placement unless you have only one sub. He would probably find that your results are correct. Corner placement does however maximize output. He believes that multiple subs should be located around the room essentially in the positions you found.

 

[John-Tompkins]

Russ Herschelmann seems to have company in his opinions. Im gonna keep the svs's split up along the walls becuase the bfd cant do much about the valleys thats caused by stacking them in a corner.

I recieved the bfd and the interface seems fairly logical but I have a couple of questions or concerns.

I realize that there are valleys that cant really be corrected by the bfd but the really weird thing is I have a couple of peaks (28,45 hz) that no matter what, I cant seem to get rid of...Ive tried settings these freq's on the bfd, lowering the gain, messing around with the bandwidth but no matter what these two particular peeks just wont go away ???.... ( I should note that if I move the spl meter a foot up towards the celing or down towards the floor that the volume is waaay lower, but at sitting level the volume just stays the same (louder) no matter what I seem to do with the bfd )

Also Im not really clear after reading snapbug about how you process two different signals at once...Should I use couple mode ? or not use couple mode and set individually..The only time I can get both the L and R buttons lite at the same time is in couple mode, But the manual states that whatever the last individual signal that was edited will be COPIED to the other channel as soon as you put it in couple mode ?

 

[Wayne A. Pflughaupt]

Well, since you’ve gone with asymmetrical placement, the two SVS’s now have their own signature room response curves. You’re going to need an EQ channel for each of them.

You already have your work cut out for you dealing with the two B5s in separate locations, and the SVS’s. You’re only going to complicate things even more by splitting the SVS’s, especially if you go with asymmetrical placement. As you’ve already seen.

Regards,
Wayne A. Pflughaupt

 

[John-Tompkins]

Wayne,

You make some good points and Im not saying I disagree..I am saying that now that Ive been messing around with the bfd that my head is spinning

The freakin phase control and distance settings has a HUGE effect on where my peaks and valleys are to begin with...Im just not sure where to start the distance and phase out before bfd ??

There seem to be sooo many variables...

To your point, I have a small room and 4 subs so I dont really need the extra spls..but Im gonna go ahead and put them both in the corner as you suggested and go from there (It looks must more asthetic anyhow).

I got everything fairly flat BUT I think I had to increase the gain at to many spots,,instead of decreasing the other areas...plus I used 10 filters for the b5's..probably to many

 

[Greg Bright]

Yes, Wayne's reply was incredibly well thought-out. Fully through-composed with no repeats. My experience with the BFD has indicated that I should NEVER use the gain. Just a little bit and those nasty red lights start blinking. And I've heard it (distortion), too. My technique has been to turn the gain up on the sub until the valleys aren't TOO bad (except for the real for-sure nulls) and the lowest Hz the sub will reasonably produce is more or less flat with the rest of the spectrum. This may make your peaks unbearable when 20 Hz is at 70-80 dB. Then its cut, cut, cut. Doesn't stress out the BFD, and it gives you lots of breathing room to experiment and adjust more to your liking.

Greg Bright

 

[Eric:F]

hi wayne and greg,
i have a svs pb2+ in the main ht room and a hsu vft3-mk2 in the family room set up.
i want to eq both subs independently with one bfd.
all gear is centerally located and controled via rf link so cable logistics aren't an issue.
can you describe the bfd set up that will allow this.
i don't think i want to be in "couple" mode.
the manual is a bit vague about using both channels independently.
thanks,
eric