My BFD results are in! (1 Viewer)

[brucek]

Jeff,

Well, your partially correct. If you were listening at low levels and you increased a particular frequency because there was a valley at that spot or you just wanted to boost it up as you have done by 10dB - as long as there was sufficient voltage output left in the BFD to increase at that frequency without clipping and if that increased voltage, when fed to the subwoofers amplifier, wasn't of a sufficient level to begin the amplifier compressing the signal to avoid clipping, the sound would indeed be louder and you would be happy.

But, if you were listening at a loud level in some action movie (to an explosion) and that frequency came along that you had the BFD boosting on its output, you may not be so happy.

First there is the possibility of the BFD running out of voltage room, and you could clip the output signal - bad news to feed to a sub amp.

Or, if the signal gets out of the BFD at a voltage level to cause the subwoofer amplifier to compress the signal to avoid clipping, then it would sound compressed - yuk.

If this situation happened to someone that didn't have a commercial amp that would compress overload signals and you had a DIY sub or maybe an SVS with a regular amplifier - you might hear that awful metallic clank, clank of your driver bottoming out.

But, agreed, a small boost and normal listening levels, you should be fine...

brucek

 

[Wayne A. Pflughaupt]

Brucek wrote:

Wayne, how much of a gradual rise do you suggest?

As I’ve noted before my slope is a 9-10dB rise from about 100Hz to 32Hz, and flat below 32Hz. The curve needed is room-dependant: Smaller rooms require less than larger rooms. Mine is 6200 cubic ft., so you can compare your space to mine to decide if you need more or less . (You have to include all areas that open to the home theater area when calculating cubic ft.) For more detail I suggest checking out my posts (of admittedly epic proportions) on this thread:
http://www.hometheaterforum.com/htfo...threadid=51646
For instance, consider Mike's equalized and unequalized readings. Ignore the meter readings and play test tones at 25Hz and 40Hz: I know it reads flat, but does it sound flat? In other words, do both signals sound the same or does 40Hz sound louder? If 40Hz sounds louder, you need to introduce a house curve. Otherwise when those explosions with energy from 20Hz to 80Hz happen, you are hearing the upper end of that more than the lower end. In other words, you are being “robbed” of that gut-wrenching, low-freq impact.
In Mike's case I would suggest setting a filter for 2/3-octave centered at 40Hz and cut 6dB. This should give you a pretty straight drop from 32Hz down to 50Hz valley.
Another 2/3-octave filter centered at 63Hz and cut 10dB would bring that hump down in line with the new slope.
This should roughly get you a 12-13dB rise from 100Hz to 32Hz. As noted, you need to decide with listening tests if this is the curve you need. If your area is smaller than mine, this slope might work fine. If it is larger, you will want to decrease the slope.
Another thing: I have only precisely tested the house curve in my own home theater. Usually when I am EQing, it’s professional system in a big auditorium, and I just don’t have 20 hours to dial it in to perfection (and besides, most of those subs bottom out at 35-40Hz). That said, you might find that my “outer limits” of the curve (32Hz and 100Hz) need to be moved up or down to “get it right” in your own room.
Regards,
Wayne A. Pflughaupt

 

[MikeHalder]

Wayne,
Your posts have been very informative and logical.I really value the comments from those who participate in this forum. There is a lot of information and learning to be had! The house curve does sound better in my environment. It makes a lot of sense to treat the hump from 50HZ to 70HZ as a peak instead of an extension of the plateau. I usually cut my subs freq around 50HZ in car audio as the sound is much more appealing to me, more natural, less ghetto, if you know what I mean. This will usually allow for cleaner bass

 

[Rick Radford]

Mike,

Just a fyi. On my 19" screen, I am having to scroll right and left to read the thread. I believe it's because your jpg's are a little big.

I found that (using Paint), I could shrink the images(control-W) to ~85% and they fit the screen just fine.

Interesting thread!

 

[MikeHalder]

Rick,

Sorry,I am so use to my 21" monitor that I forget to reduce images for other screen sizes.

Mike:b

 

[Steve Morgan]

Very informative thread! To Sonnie, Rick, BruceK, and especially Wayne, I want to say Thank You For all your help in setting up my BFD and helping me with this process.My hum is gone, it was those F!#*!g Monster cables from the pre/pro to the BFD.I set the input level tonight and will take baseline readings tomorrow with the subs in their new location. I can't express how much better it is with a sub not in your face!I had 1 sub along the back wall 2ft. from my listening position the other in the corner now with both in the corner you can't spot the sub so readily by listening.It also has improved the poerformance of my new Von Schweikert speakers. I can't wait to get both equalized with a curve thrown in. Once again thanks for your help and patience.
Regards,
Steve Morgan

 

[Wayne A. Pflughaupt]

Take a look at this graph and let me know if this is the type of house curve you are referring to.

Certainly looks better, Mike, and from what you say it sounds better too. See? Told ya!

So, you have a 15dB slope, quite a bit steeper than mine. Either your total area is smaller, or you’re a serious “bass head.”

For the record, what is your cubic ft.? That would sure help me help others.

Someone needs to send Steve a sympathy card. He’s been battling his sub situation since -- what, Steve, October? Ya gotta admire that kind of determination!

Regards,

 

[Rick Radford]

Mike,
Thanks for fixing your images! No more scrolling (for me!).
If you get around to it, post your filter parameters. I think it's helpful to others going through this to not only see (with graphs) what you've been able to do.. but also the filter specifics.
I am curious what your BW settings are.
Steve, glad your hum is gone! On your BFD input settings, did you have a chance to review Brucek's information (link from Sonnie's site)?

 

[gomez_a]

I would like to publish my pre-BFD response curves, so how do I cut and paste my excel charts for other to vierw on this site. I dont have a website where I can provide a link for people to see the graphs
publish, or better yet . . . . post or perish!!!

 

[Wayne A. Pflughaupt]

Gomez,
Graphics are cool and show everyone you're a techno-stud , but you don’t really need to post one. Honestly, I don’t know how to do it either. If you can post 1/6-octave corrected readings I can work from that.
Regards,
Wayne A. Pflughaupt

 

[gomez_a]

Hi Wayne,
A pic is worth a thousand words they say. I have a unqiue setup: a polk PSW650 stacked atop SVS 16-46PC in front left corner of my living room. I've orderd a BFD and should get it this week - I hope.
Anyway, Let me start a separate thread so as not to hi-jack this thread

 

[MikeHalder]

Wayne & Rick,

Here are the stats you were wondering about. Its amazing how easy it is to use this EQ once you understand how the menus work, fine tuning adjustments are a snap. I just wish I knew of this piece of equipment a long time ago. I have learned a lot about how different frequncy curves affect the actual sound of the sysem. That in itself is worth the price of admission.I can't thank you enough Wayne for taking the time to post in this thread and give me some much needed direction.Oh, and by the way, I promise not to post any more graphs, its just that I am a very visual person and found that these graphs might help others who work better with visual feedback. I hope others have benefited as much as I have from this tread and the insight it offered in setting up a BFD.

Room: 15x20x8 2400 cubic ft

Filters:

Freq fine BW gain

20 +8 6 +3

40 0 8 -1

40 +10 8 -2

50 0 5 +5

50 +10 6 -4

63 0 8 -5

63 +10 6 -1

80 0 6 -4

Cheers,

Mike

 

[Wayne A. Pflughaupt]

Why don’t you go ahead and post a graph, Mike? I only said that for the benefit of those who don’t know how. I’d like to compare you current readings to your others without taking the time to plot a chart (and I’m sure everyone else would like to see it, too).
Regards,
Wayne A. Pflughaupt

 

[Sonnie Parker]

If you fellows need a good image editor I will send you a copy. It's one of the finer ones. But you need a high speed connection to download it. I will give you access to my ftp server temporarily for the download. Send me an e-mail. Then you can do all kinds of things with those images. But warning, it's another learning process if you are not familiar with such. Not really bad though.

What screen resolutions are you fellows using to view?

Steve, I know you are excited to have that hum gone. I know it would bother the heck out of me until I did something about it. Those Monsters weren't shielded were they? So, you ended up stacking them in the same corner? I would think that would do you better with phase problems anyway.

Anytime you have these fellows on your side you can't go too wrong. They are truly great folks.

Mike, the graph is looking good. If it sounds good then you may be set. Have you taken some measurements now with your mains?