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Bought my BFD and I Have Questions (1 Viewer)

Rick Radford

Supporting Actor
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May 12, 2001
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642
Bob,
You're already in good hands with Wayne and brucek on the scene.
However, if you're feeling adventerous, drop by this site and pick up the free demo of ETF. IF, and I say, IF the SDA mode works in the demo (and I think it does.. brucek?), you can plug in those filters Wayne came up with and modify the BW while you watch the results onscreen. (Sure beats the manual method, IMHO!) And, you can vary any parameter and watch the results onscreen in 1.5 seconds. Definitely cool!
SDA mode = Sequential Data Acquisition mode.
The learning curve for ETF is a bit steep, but I figure if I can learn it, anyone can. ;)
Wayne: check out this thread for some more followup on EQ'ing (in case you missed it). brucek started it.. and Sonnie and I sorta ran with it. ;)
 

Bob U

Stunt Coordinator
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Oct 6, 2001
Messages
137
Wayne,
Here is the curve with your filters and the filter at 50Hz CUT 8dB instead of boosted. I'm sure that was a typo on your part.
Images deleted. See new curves below.
I seem to have lost too much at 20Hz and will tighten that filter. Then I'm going to drop 31.5 about 3dB more. Actually, I just plotted out what I am going to try to change. I'll post a chart and filters if it looks better.
Back soon....
-=Bob=-
 

Wayne A. Pflughaupt

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That third filter at 50Hz should be MINUS 8dB, not PLUS, correct? And if so, shouldn;t it be tighter?
50Hz was originally a pretty low point, so I did mean boost it. And the area above 56Hz should have smoothed out better than this, and there should be a smooth, 6dB rise between 100Hz and 50Hz.

It looks like some of those filters must spill over further than I expected. Nevertheless, if the 40Hz hole can be eliminated, this one at 50Hz can, too. A 1/6- or 1/8-octave filter ought to do it.

Nevertheless, you’re on the right track.

Regards,

Wayne A. Pflughaupt
 

Bob U

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Hmmmm, 50Hz has always been a peak, Wayne. There are dips (or were) at 40 and 56.

Ata nay rate, I now have created 11 filters and I'm going to go plug them in and see where I am. If it looks beter, I'll post a graph and my filter settings. Back soon...

AND, you never did answer what "Luby's is"?

-=Bob=-
 

Wayne A. Pflughaupt

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Hmmmm, 50Hz has always been a peak, Wayne. There are dips (or were) at 40 and 56.9
You’re right of course. I see I made an error when I transferred your Hz/dB readings to graph paper (for erasure exercises :)). Sorry about that.
Luby’s is:
  • A cafeteria chain – guess they don’t have them in California.
  • A lame attempt at humor. Guess I should stick to what I do best. :)
Regards,
Wayne A. Pflughaupt
 

Bob U

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Well, I've been doing this all day and I am bleary eyed. About to do my ylast filter changes for the night and I will post. Its not as good as I would have hoped, and I am constantly surprised that the changes that look good on paper do not always bring about the expected result. I just tossed about thirty curves that weren't it.

I'll post the filter chart as well. Wayne, note that the numbers in the bandwidth column are x/60's of an octave. In other words, if it says 15, than that means 15/60ths or 1/4 octave. The Setting + Fine is just the BFD's way of setting the center frequency mentioned in the 2nd column.

Appreciate any feedback. Back in just a little while.

-=Bob=-
 

Bob U

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Oct 6, 2001
Messages
137
Ok, this is it for tonight. Time to eat 8^)
Any suggestions?
Images deleted. See new curves below.
-=Bob=-
 

Mike Matheson

Second Unit
Joined
Jul 15, 2000
Messages
416
Bob,

In your last post I see columns for "Filter", "Freq", "Setting + Fine", "Bandwidth". I don't see a "Gain" type column--any info for us here?

I'm following your adventure closely trying to pick up tips on improving my curve as well. . .

M
 

Bob U

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137
Ooops. Thanks for catching that. Fixed now.

Hoping for more tips as well. Not quite happy with what I have now and repeated tries all day long didn;t make much improvement.

-=Bob=-
 

Bob Christensen

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100
Wow, I am surprised that the 40Hz null EQed out so easily! At first I thought that the 40Hz and 56Hz nulls were likely either room interactions, or phase cancellations between the two subs. They still might be, but in my experience, these phase-related nulls do not typically respond very well to boost. You may want to experiment a little bit to determine is the nulls are room interactions (by moving around with your SPL meter as you measure a 40 or 56 Hz tone), or phase interactions between your two subs (by simply turning off one sub).
 

Bob U

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I was , too. The 40Hz went away. The 56 doesn't seem to move even with 8dB of boost.

-=Bob=-
 

Wayne A. Pflughaupt

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Bob,

Remember what I said before about the 40Hz filter:
If this results in a gain change of only 2-3dB at 40Hz, then you have a room null, in which case you should skip this filter.
Looks like you have a genuine null at 56Hz, Bob. I would have expected the deepest “hole” to be a null, if there was one, not one of the minor ones. Just goes to show most of the “absolutes” in the low frequency/EQ game seem to be etched in sand rather than carved in stone.

So it looks like you’ve done about all you can do. Nevertheless, when you compare EQ’d response to the original curve I think you’ll agree the BFD made remarkable – even amazing – improvements, and the results should be readily audible. I expect with program you will never notice the problem at 56Hz. It is pretty narrow, after all.

Regards,

Wayne A. Pflughaupt
 

Bob U

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Oct 6, 2001
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Nope, nope, nope!
Woke up this morning refreshed and THIS seems to be the best I can do ;) , though there is always a bandwidth thing to tweak.
Images deleted. See new curves below.
Though just listened and it sounds superb on music, Chap 32 of Matrix was a bit weak. I may have to agree with you, Wayne, that it needs a bit of a house curve. Since I have problems at 56Hz, and music sounds so good, I'm going to try bringing everything 40 and below up a few dB.
Thanks to all for the help. Its getting there!
-=Bob=-
 

brucek

Second Unit
Joined
Dec 29, 1998
Messages
335
Just a second Bob, before you do anything else.

What about a wholesale increase of your sub volume control now, to give you a +10dB above mains level setting that a lot of people use. I think you have a (after much work) fairly nice response there. You've been listening to that horrible hump before, but once it's equalized, you think it's shy on bass.

Did you go back after this equalizing chore and reset the level of your sub? Try that first maybe.

brucek
 

Bob U

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Oct 6, 2001
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Sub level matches the mains very well right now, and music sounds very good. So I am reluctant to raise the entire sub level and boost anything above about 60Hz.

A good example of what is a little thin is that Chapter 32 Helicopter scene in Matrix. The sound of jumping on the roof and the slow sweeping of the rotor blades are both lacking. I wish I knew where those fundamentals were, but I am guessing between 20 and 30. So, I *think* I'd like to boost 40 on down.

Any thoughts?

-=Bob=-
 

Wayne A. Pflughaupt

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My thoughts are that I think you’ve EQ’d to far, Bob. Your previous graph showed smoother response and a house curve of about 15dB from 100Hz to 20Hz. Now response is rougher and you’ve reduced the house curve to 10dB - which is why it sounds lacking at the low end now.

Regards,

Wayne A. Pflughaupt
 

Bob U

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Not sure I understand, Wayne. This curve looks the smoothest overall to me. It is flatter, and I am beginning to believe in the House Curve theory, but why would you say this is rougher?

As to House Curve, do you believe it needs to rise from 100 down or would 50 down suffice or even be better? How does one choose from a curve of 8,10 or 15dB? Isn't Dolby or DTS adding 10dB to the LFE output on the software side?

Now that I have found what I belive to be the flattest curve I can achieve with my room/equipment, I am not sure what it really is that I want. Particularly since music is as important to me as is HT.

-=Bob=-
 

Wayne A. Pflughaupt

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Do you believe it needs to rise from 100 down or would 50 down suffice or even be better?
A rise starting at 100Hz worked best in my room, but you might need a different starting point. Experiment using the method above, only make the comparison between 50Hz (or whatever point you want try) and 31.5Hz. (Actually since you know 50Hz is a null in your room, you should choose a different frequency for your trials.)

Regards,

Wayne A. Pflughaupt
 

Bob U

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Oct 6, 2001
Messages
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Just a note to say that I have played with sub level and it makes a BIG difference now. But raising the level has thrown a lot of things out of whack. Dips and bumps are now more pronounced and I'm afraid I have mucked things up a bit.

Ran out of time yesterday, but will start now with a new curve with the BFD bypassed, then make some corrections and see what I can do to the EQ'd curve.

I'll post more when I have new information. Got a lot of hours into this project now and I'm not going to stop until I feel I "have" it.

-=Bob=-
 

Sonnie Parker

Second Unit
Joined
Dec 11, 2001
Messages
409
Bob,

First, let me apologize for the error on the 2 flashing dashes. I'm not sure where I got that from or if it was just a typo. You were the first to notice this. Thanks and I will get this corrected asap.

Let me poke my nose in here and make a couple of small suggestions for what it may be worth. Not that your response doesn't look good but this might be worth trying anyway.

In reference to the cut at 51hz, boost at 56hz, and cut at 63hz. Those appear to be really fighting each other.

I know it can get weary eyeing doing all these experiments but try this and see if it might help. I believe it will!

Try narrowing the cuts at 51 and 63, they seem to be keeping the 56hz from budging, they have actually brought your dip at 56hz down a db or 2 despite the boost. Maybe try a bandwidth of 4 at 51hz and 4,6, or 8 at 63hz. Both of those peaks look similar yet you have different bandwidths. You may have to adjust the gain a little after adjusting the bandwidth.

The dip at 56hz is also similar to the peaks in width. Maybe try a bandwidth of 4,6, or 8 there as well.

You may end up having to address the boost at 45hz somewhat but that shouldn't be a major problem.

I would start with the smaller number first and work up. It's easier to see the change and it's effects if you start small. After each filter setting, don't go to the next one (if you have been), take new measurements and see what it does.

Just my experience with the BFD.
 

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