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Discussion Starter #1
Hello All,

First, I want to thank all of the people who have posted articles and their thoughts here at The Shack. It really seems like I have read all of the available information here on REW & BFD.:reading:

Ok, here is what I have to work with::bigsmile:

Polk Speakers all around:

Fronts are RtiA3 (Bookshelf). FR is 50 – 26Khz (-3dB)

Center is CSiA6. FR is 55 – 26Khz (-3dB)

Surrounds are FxiA6. (Dipole Setting) FR is 55 – 26Khz (-3dB)

Back Surrounds are RtiA1. FR is 60 – 26Khz (-3dB)


(2) Outlaw Audio LFM-1 PLUS Subwoofers:

Down Firing, 12” Long-throw Woofer
Dual 3” Ports
350 WRMS (1300W Peak) BASH Amp
25Hz – 180 Hz +/- 2 dB w/o plug (Max Output Mode)
18Hz – 180Hz +/- 2dB with one port plugged (Max Extension Mode)
SPL = 115dB
Each sub set to Max Output
Each sub’s volume control is at 3 (10 o’clock position)
Phase is set to “180”


(2) Outlaw Audio LFM-1 EX Subwoofers:

Down Firing, 12” Long-throw Woofer
Dual 3” Ports
350 WRMS (1300W Peak) BASH Amp
22Hz – 180 Hz +/- 2 dB w/o plug (Max Output Mode)
16Hz – 180Hz +/- 2dB with one port plugged (Max Extension Mode)
SPL = 118dB
Each sub set to Max Output
Each sub’s volume control is at 3 (10 o’clock position)
Phase is set to “0”

I have lifted all four subs, using an extender to the carpet spikes, off the carpet to maintain a 2” gap between the bottom of the sub and the top of the carpet.

Onkyo 805 AVR with the following settings:

Line Level input to the subs via a Y-cable adapter from the sub out (through the BFD). The cross over is set for all speakers to 80dB and the LPF for LFE is set to 120dB. Double bass is set to OFF and the sub’s trim level is set to –5dB. I used Audyssey with 8 measurements around the couches and the speaker trim levels were adjusted to read 75dB using the RS analog meter set to “C” & “Slow”. Each sub was set individually to 75dB and combined produce 81dB. All of the above calibrated with the test tone from the 805.

I also have a Behringer Feedback Destroyer Pro #DSP1124P that I will use as a PE.

My Dedicated Theater Room:

The room is 20’ x 15’ with a cathedral or sloped ceiling starting at a height of 9’ (The Left Wall) that slopes to a height of 11’ (The Right Wall). The ceiling is exposed with (6) 4” x 10” solid oak beams supporting a tongue & groove hardwood roof. Standard drywall walls and a poured concrete floor with ½” thick high density carpet pad & ½” thick pile wall to wall carpet. There are two couches located 4’ from the back wall.

I have a built in “entertainment center” that spans the entire 15’ width of the room and extents 2’ into the room off the far front wall. I have my 61” TV located here as well as the FR - FL- C speakers. Sub #1 is placed along the left wall (9’ height) at it’s mid-point. Sub #2 is placed along the right wall (11’ height) at it’s mid-point. Sub #3 is near the back left corner of the room located 3’ from the back wall & 4’ from the left wall. Sub #4 is near the back right corner of the room with the same spacing. Both subs are placed directly behind our couches.

The entrance is a solid wood door (36” wide) located in the back left corner of the room.

Ok, here is my graph::ponder:

first graph rew.jpg

With a Hard Knee House Curve and three filters from REW, I have this now::ponder:

first graph with filters.jpg

I would appreciate any & all comments and suggestions.:whistling:

TIA
 

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Those are my fav frequencies you have a peak there in but the 50Hz with that dip is also one of my areas I commonly enjoy so you were close. I like the equipment. I would have to see a picture of the room to know what to do. :no:
 

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Larry,

First I would suggest that you give me one of your EX's! :bigsmile:

Actually, it looks maybe you lowered the 30Hz are too much? It looks like it pulled the 50Hz area down too far. Other than that, I am jealous.

I thought this was fitting for you......:hsd:
 

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Larry,

Did you use smoothing when setting up your filters? I saw this quote of brucek's:

"Only use smoothing when looking at full range signals such as yours. If you are looking at a sub signal from 15Hz-200Hz, do not use smoothing, as any filters you create will not match the modal resonances they are designed to eliminate."

:hide:
 

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Discussion Starter #6
Larry,

First I would suggest that you give me one of your EX's! :bigsmile:

Actually, it looks maybe you lowered the 30Hz are too much? It looks like it pulled the 50Hz area down too far. Other than that, I am jealous.

I thought this was fitting for you......:hsd:
Hey weverb, I would give you one of the EXs but, you know, a birthday gift from the Wife.:kiss:

Ya, I am looking at that 50Hz area, but I love the way this sounds in my room. I have moved all four subs all around the room and that was the least dip I could manage.

Larry
 

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Discussion Starter #8 (Edited)
Larry,

Did you use smoothing when setting up your filters? I saw this quote of brucek's:

"Only use smoothing when looking at full range signals such as yours. If you are looking at a sub signal from 15Hz-200Hz, do not use smoothing, as any filters you create will not match the modal resonances they are designed to eliminate."

:hide:
Yes, I used 1/6 smoothing to generate the filters. I'll re-run the filters with no smoothing and compare the results.
 

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Discussion Starter #10
Wayne, thank you for your comment. I enjoy reading your posts and I have gone ahead and entered a 6dB boost into my BFD

Larry
 

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Wayne, thank you for your comment. I enjoy reading your posts and I have gone ahead and entered a 6dB boost into my BFD

Larry
So what does it look like with the new 6dB boost?
 

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Discussion Starter #13
New Graphs

So what does it look like with the new 6dB boost?
Hey weverb, here are the new graphs along with the vertical scale that Wayne talks about:

First is Max Output Mode on all 4 subs, Hard Knee House Curve @ 75dB TL w/ 1/3 smoothing octaves:

hk house curve mo.jpg


Second is Max Extension Mode, Hard Knee House Curve @ 75dB TL w/ 1/3 smoothing octaves:

hk house curve me.jpg



I will try these out tonight!

Larry
 

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I can't wait to hear/read your thoughts on the new filters. They look almost the same but for the very low Hz area. :hush:
 

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Discussion Starter #15
Update

Here are some updated graphs::whistling:

Subs only using the BFD with 5 filters.

hard knee final.jpg


Subs + mains using a RS Meter with 1/3 smoothing.

with fronts.jpg

Can I or should I do anything in the area between 100Hz to 300Hz? Is the BFP 1124P suitable for this range?

Thank you!

Larry
 

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In the second graph, should the hard knee curve be added?
 

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@ 75dB TL w/ 1/3 smoothing octaves
What is the reasoning for using smoothing on subwoofer plots. I know it makes the graph look nicer with respect to frequency response plots, but you're not doing yourself any favours when it comes to obtaining the best sound.

As was quoted in a post above, you should only use smoothing when looking at full range signals. If you are graphing a sub signal to 200Hz, do not use smoothing, as any filters you create will not match the modal resonances they are designed to eliminate. The purpose of a filter isn't to simply affect amplitude, but it also operates in the time domain.

REW's filter recommendations are designed to find the optimum center frequency and appropriate bandwidth to reduce amplitude and decay time of a modal resonance. Smoothing will shift that center frequency and upset the bandwidth of the modal resonance and such, the filters will not be as effective. You should stop using smoothing on subwoofer plots.

In addition, I see little reason in widening your vertical axis to levels that don't represent your hearing. It may look nice, but it's best to adopt a standard that everyone else uses that has a typical noise floor of 45dB and a swing of +/-30dB. This would be the area a typical subwoofer would operate in a home environment.

Is the BFP 1124P suitable for this range?
Since the BFD is connected in the subwoofer chain, it is limited to below the range you're asking about. That would require inserting the BFD in your pristine mains chain. Not really advised....

brucek
 

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Here are some updated graphs::whistling:

Subs only using the BFD with 5 filters.

I'd pull down the area between 45-100 Hz. You need to track the hard-knee line pretty hard to get the most benefit from it. Otherwise your slope, say if it's supposed to be 8 dB, it ends up only 4 dB, for instance.

Regards,
Wayne
 

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Discussion Starter #19
What is the reasoning for using smoothing on subwoofer plots. I know it makes the graph look nicer with respect to frequency response plots, but you're not doing yourself any favours when it comes to obtaining the best sound.

As was quoted in a post above, you should only use smoothing when looking at full range signals. If you are graphing a sub signal to 200Hz, do not use smoothing, as any filters you create will not match the modal resonances they are designed to eliminate. The purpose of a filter isn't to simply affect amplitude, but it also operates in the time domain.

REW's filter recommendations are designed to find the optimum center frequency and appropriate bandwidth to reduce amplitude and decay time of a modal resonance. Smoothing will shift that center frequency and upset the bandwidth of the modal resonance and such, the filters will not be as effective. You should stop using smoothing on subwoofer plots.

In addition, I see little reason in widening your vertical axis to levels that don't represent your hearing. It may look nice, but it's best to adopt a standard that everyone else uses that has a typical noise floor of 45dB and a swing of +/-60dB. This would be the area a typical subwoofer would operate in a home environment.


Since the BFD is connected in the subwoofer chain, it is limited to below the range you're asking about. That would require inserting the BFD in your pristine mains chain. Not really advised....

brucek
Thank you brucek for your thoughts. I will re-do my filters w/o smoothing and enter them into the BFD.

Larry
 

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Discussion Starter #20
I'd pull down the area between 45-100 Hz. You need to track the hard-knee line pretty hard to get the most benefit from it. Otherwise your slope, say if it's supposed to be 8 dB, it ends up only 4 dB, for instance.

Regards,
Wayne
Thank you Wayne. I will re-do my filters and faithfully track the hard-knee curve.

I really, really appreciate all the time that you & brucek put in to this forum.:hail:

Larry
 
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