BFD owners - please comment on my curves! (1 Viewer)

[Henry Yuen]

I bought a Behringer Feedback Destroyer recently but am not 100% sure if I'm doing the right things with it. I'm using a Pioneer receiver and a Velodyne CHT-15. I'm using the receiver's crossover, set to 80Hz.

Here are my 'before and after' curves:



As you can see, there's a wide peak around 32Hz which I've tamed by setting up a filter with a bandwidth of 10/60 and gain of -12. Is that the correct thing to do? Should I be applying other filters or is the curve flat enough?

Any advice would be much appreciated.

 

[Henry Yuen]

Anyone?

 

[Seth_L]

You should use all the filters until you get as flat of a response as possible. Either cut or boost other frequencies where the sub isn't flat.

Seth

 

[Sonnie Parker]

Henry, I would maybe try to bring it on down to -18db or more. The 10/60 bandwidth is affecting the 40-50hz area also, you may want to consider using 2-3 filters for this area with narrower bandwidths.

Suggesting maybe 4/60 or 6/60 at 30hz and 34hz. You may have to experiment with different settings to make sure the filters don't affect the dip area any.

Then do the same for the 56-70hz area with less cut obviously. Possibly a 2/60 or 4/60 -5db filter at 58hz and same bandwidths with a -3 or -4db cut at 66hz or thereabouts.

Then you may try a slight boost of + 2 or 3db at 48-49hz.

This should give you somewhat of a house curve. If you want it flatter then you may have to cut the area from 25hz to 36hz more.

I usually start with smaller bandwidths and work up each measurement to see how the bandwidth settings are going to affect the other frequencies.

Good luck!

 

[DerrickW]

I've been reading about these units, and to be really type A I don't think boosting anything is recommended. However, you could improve by cutting only the peaks (you dropped almost everything a little, especially that dip at 50Hz is now 2dB worse).

I bet this already sounds much flatter than before, and most people probably don't like "flat" anyway. I personally would try to get that 40-56Hz range back to where it started by using smaller bandwidth filters, and then bring everything else down to that 80dB level. Hopefully you still have room to calibrate the system to louder SPL when desired. If you are already maxing your levels out, then maybe you'd rather have a few bumps. Its all personal preference, so have fun.

 

[Sonnie Parker]

You'll be okay boosting a few db's at 48hz or so....

I would not recommend boosting frequencies below 30hz if I could help it but when you get to 50hz or so the boost (provided they are only a few db) will not hurt a thing.

 

[Henry Yuen]

That's exactly the kind of expert advice I was looking for. Thanks!

 

[Henry Yuen]

And here are the results:

 

[DerrickW]

Hey, I like that a lot better. What are your impressions listening? Since that's a lot more important! You could certainly flatten it more, but it may not sound "better" to you.

At this point it's just playing, but maybe try bringing 55-71 to 80dB and then get 22-37 down to 85ish. I still would keep the slope going up towards lower frequencies though, because you hear it less and feel it more with them.

 

[Henry Yuen]

I spent so long playing with the filters last night that I was too tired to have a good listen! First impressions are very good though. I must say it was quite fun rather than frustrating (as I expected before I bought the BFD).

 

[DerrickW]

Can you give us your impressions of the BFD itself? Does it attenuate the signal, add any noise, have any quirks, etc?

 

[Sonnie Parker]

It's frustrating to have a slow connection.... I can't get your image to pull up Henry...just a little white box with a red X. I'll have to wait til tomorrow and see it at the office.

If it's not too much trouble can you post your filters? Freq/BW/Gain or Cut

Derrick, the BFD is very clean. You shouldn't get any additional noise and there are no quirks.

You can check out the specs in the manual which is linked on the BFD page throught the link in my sig.

 

[Henry Yuen]

Sonnie, I think it's a problem with my host rather than your slow connection. I'll try to sort it out and also post my filters later.

Derrick, I did notice a hum from the sub when the BFD is connected but this has been eliminated by setting up several high frequency (>1kHz) filters.

 

[Henry Yuen]

The pictures seem to be working again.

Here are the 5 filters I'm using:

30Hz, bandwidth 7/60, gain -12
35Hz, bandwidth 3/60, gain -10
57Hz, bandwidth 3/60, gain -7
66Hz, bandwidth 4/60, gain -6
50Hz, bandwidth 4/60, gain +3

 

[Sonnie Parker]

Looking pretty good Henry.

It should be sounding pretty good too!

It slopes off gently for a house curve.

I see the narrower bandwidths seemed to be working for you. You could probably tweak it a little more but if it's sounding good then you could leave it as is.


I know there have been a few people talk about that hum although most could only hear it when they had their ear right next to the speaker, which is unlikely during use..... or OUCH to an ear.

 

[Henry Yuen]

It's certainly sounding great! The bass does seem much 'cleaner' than before. Thanks again for the tips.

Sonnie, could you explain to me what exactly a house curve is? Is it better than having a flat line?

 

[Sonnie Parker]

In my setup the house curve sounds better.

This is what I say about it on the site:

As mentioned earlier, you may wish to set up a couple of different presets for music and movies. You may wish to consider a "House Curve". A simple explaination is my own example. If you scroll down to the bottom of the page you will see my second setup which represents a house curve. Notice it slopes gently from 20hz to 80hz. I won't get into all the technical details about why you might wish to have a house curve but a good link to read is here in one of the forum threads. You can also do a search for "house curve" in many of the home theater forums and find more info. I will say though, once I flattened out my response to the best I could, I noticed I was missing some low end. I ended up liking the house curve because it gave me back some of that low end without any boomy peaks. As well, it helped me with my nasty dip I have. I haven't really noticed (with my hearing anyway) that I even have a dip. At any rate, the house curve is worth investigating.

If you click on the "here" link you will get some good technical information about the house curve.