# Please critique my graph



## thebuffman (Feb 4, 2009)

Okay I finally got my subs in decent locations and would like a critique of my flat response also I am looking for advice of where I may begin equalizing. I plan to use brucek's house curve recommendation once i get these results flat enough. 

The graphs below are of both subs performing together. ME = Max Extension Mode while MO = Max Output Mode. 
The first picture is my side sub in ME mode and my front sub in MO mode. Picture two is both subs in ME mode. Picture three and four are the subsequent Impulse graphs. Thanks!

test 1

test 2


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## Wayne A. Pflughaupt (Apr 13, 2006)

Please re-scale your frequency response graphs for a 15-200 Hz horizontal and 45-105 dB vertical axis. You can do that by clicking on the "Graph Limits" icon in the upper right corner.

Regards,
Wayne


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## thebuffman (Feb 4, 2009)

Here is a graph with both graphs combined.


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## thebuffman (Feb 4, 2009)

Wayne A. Pflughaupt said:


> Please re-scale your frequency response graphs for a 15-200 Hz horizontal and 45-105 dB vertical axis. You can do that by clicking on the "Graph Limits" icon in the upper right corner.
> 
> Regards,
> Wayne


wayne i must be missing something because this is the first thing that i did. i went back to double check and it is set at those specifications.

edit: sorry...i never clicked "apply" with the graph selected


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## Wayne A. Pflughaupt (Apr 13, 2006)

Have no idea what "ME" or "MO" mode is, but the graph looks great. Notch out that nasty bump at 70 Hz and you're in business. Of course, you'll also want to plot both subs running together. And don't forget to use a target curve when applying brucek's house curve filter. :T

Regards,
Wayne


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## thebuffman (Feb 4, 2009)

Wayne A. Pflughaupt said:


> Have no idea what "ME" or "MO" mode is, but the graph looks great. Notch out that nasty bump at 70 Hz and you're in business. Of course, you'll also want to plot both subs running together. And don't forget to use a target curve when applying brucek's house curve filter. :T
> 
> Regards,
> Wayne


sorry man. the graphs are both subs running together. me + mo = one sub in max output and the other in max extension. should i post a graph of the subs individually?

So which one should I work with? Where both subs are in Max Extension mode or with one in ME and the other in Max Output?


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## Wayne A. Pflughaupt (Apr 13, 2006)

> sorry man. the graphs are both subs running together.


So each trace is both subs running together, not each sub separately? :scratch:



> So which one should I work with? Where both subs are in Max Extension mode or with one in ME and the other in Max Output?


Have no idea which is which, but I think I'd prefer the purple for movies and the green for music.

Regards,
Wayne


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## thebuffman (Feb 4, 2009)

Wayne A. Pflughaupt said:


> So each trace is both subs running together, not each sub separately? :scratch:


precisely. each trace is both subs running together. i didn't see a benefit in posting graphs of my subs individually.


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## thebuffman (Feb 4, 2009)

okay here is my corrected (equalized & flat) graph *BEFORE *adding the house curve. i performed 3 filters to get this result. Filter #1 @ 92 hz (+10db), Filter #2 @ 84 hz (-6db), Filter #3 @ 67 hz (-7db). 

2 questions though:

should I even be concerned with adding filters after 80hz which is my designated cross over?
My target line (viewable on the graph is 75db). My curve is considerably above the target line. Shoud I still use this line as a basis for establishing my house curve? if so, how do I use REW's tools to create a house curve filter?


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## thebuffman (Feb 4, 2009)

*Completed Hard Knee House Curve*

Okay, I completed my first hard knee house curve. Thanks tremendously for Wayne's work. I am sure my first draft is missing the mark but I am determined!
You will find below:

Hard Knee Curve which includes a trace of my dual subs as well as the correction (dotted lines)
Filters
Plots to attain my hard knee line
I am open to ANY advice I can get. Thanks!
Please note that I did not make any filter corrections beyond 70hz because Wayne's suggestions (or my interpretation of his suggestions) deem such modifications beyond 70hz immaterial.

**the 3rd filter *BW/60 entry is 13* ...sorry for any confusion


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## Wayne A. Pflughaupt (Apr 13, 2006)

Hmmm... What happened to that severe dip at 90 Hz? :scratch:

Your predicted curve looks good. You might go ahead and dial up a filter at 85 Hz and see what happens. If the peak reappears after the mains are added, then you can take out that filter.

Regards,
Wayne


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## thebuffman (Feb 4, 2009)

wayne i wondered about that too! after i put all my furniture back in place and tweaked the position of my subs a little for aesthetics the dip went away. i ran a test multiple times to be certain and it was sure enough gone. this mode stuff is way beyond my comprehension. 

okay i will add a 85hz filter. question for you though. well first THANKS to you! that write up you did on a hard knee curve man is brilliant. it took a while for me to understand it but that is simply because of my learning disability. it is very well written though. question: even though i am plotting a 6db drop from 30hz to 80hz, the graph shows more of a 12db drop. i even checked the graph in your write up and although you went from 30hz to 90hz it was still somewhere around the ball park of 12db drop. how does it go from 6db to 12db?? this has me tremendously confused.


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## thebuffman (Feb 4, 2009)

how is this? i also disabled the 1/6 smoothing so you could see some of that 90hz dip you spoke about


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## Wayne A. Pflughaupt (Apr 13, 2006)

Thanks for the feedback on the article, Will! I try to write this stuff so that it isn't lost on novices; nice to hear I was successful. :T Your hard knee graph looks great, assuming you can get it to look like that after EQing.



> even though i am plotting a 6db drop from 30hz to 80hz, the graph shows more of a 12db drop. i even checked the graph in your write up and although you went from 30hz to 90hz it was still somewhere around the ball park of 12db drop. how does it go from 6db to 12db?? this has me tremendously confused


.
Well, you're already getting a certainly amount of drop at 90 Hz because of the crossover. The house curve slope is added on top of that. You want to keep your eye on the shelving frequency and below, not the top end of the sub range. With the slope added, the Target Curve should rise in your case 6 dB. Looks like yours went from 74 dB to 80, so you're on track.



> how is this? i also disabled the 1/6 smoothing so you could see some of that 90hz dip you spoke about


The main reason to use smoothing would be to prevent REW's auto EQ function from going overboard on the equalization, or to help keep people who are manually equalizing from doing the same thing. You don't seem inclined to do that, so go ahead and stick with the unsmoothed graphs.

Regards,
Wayne


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## thebuffman (Feb 4, 2009)

Wayne your mentoring paid great dividends! :yay2: Take a look at my finalized dual subwoofer graph with the FBD in-place and fully functional. I removed that bump @ 45hz as well. I ran a test tone against the equalized subs. What do you think?


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## Wayne A. Pflughaupt (Apr 13, 2006)

Nice! :T

Regards,
Wayne


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## thebuffman (Feb 4, 2009)

Wayne A. Pflughaupt said:


> Nice! :T
> 
> Regards,
> Wayne


well sir, i require your help again. its seems like all the good hard work i did is wiped out. one of my subs was configured improperly, and, according to the manual, it might damage my sub. i had a port plug inserted (maximum extension mode) however the switch on the back of the sub was set for 'no port plugged' (maximum output mode). i set the switch to the proper setting and my graph went to the pits. there is some crazy mode in my room that was fine with an improperly configured sub but has a real attitude at a properly configured one. i moved the subs 2 miles around that room and finally found a decent setup. i created new filters and everything looked pretty good.


AND THEN I ADDED THE MAINS TO THE EQUATION :yikes:



That didn't look good so i pushed the mains back toward the back wall some to see if that would help



i'm stumped bro. with the mains added to the equation, things dont look so good anymore. any suggestions where i should start?? :reading:


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## Wayne A. Pflughaupt (Apr 13, 2006)

thebuffman said:


> i'm stumped bro. with the mains added to the equation, things dont look so good anymore. any suggestions where i should start?? :reading:


Relax – take a deep breath! It’s not nearly as bas as you think! If your subs have a variable phase control, it might clean up things around the crossover frequency. It might be easier to do that with REW’s RTA function, which will let you see the response changes in real time.

Regarding the mains, the away-from-the-wall response (green chart) is much smoother overall (at least between the crossover frequency and 200 Hz!). I‘d go back with that. Beyond that it looks like the sub level could be brought up – I’ll bet the bass sounds a bit weak at the moment. After that you should be in business. :T

Regards,
Wayne


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## thebuffman (Feb 4, 2009)

Wayne A. Pflughaupt said:


> Relax – take a deep breath! It’s not nearly as bas as you think! If your subs have a variable phase control, it might clean up things around the crossover frequency. It might be easier to do that with REW’s RTA function, which will let you see the response changes in real time.


:whew:thanks for lifting that heavy load:whew:
unfortunately i do not have variable phase control. i can only set it for 180 or 0. i am going to switch to 180 and see what it looks like. i'll post final results.



> Regarding the mains, the away-from-the-wall response (green chart) is much smoother overall (at least between the crossover frequency and 200 Hz!). I‘d go back with that. Beyond that it looks like the sub level could be brought up – I’ll bet the bass sounds a bit weak at the moment. After that you should be in business. :T


okay, thanks for the insight. i'll stick with pulling the mains away from the wall, and bring up the sub level one notch on both subs. how did you notice that i had dropped the subs' level down? and what is an appropriate level to set them at? i know the general answer is "whatever sounds good to me" but is there a general rule of thought?

here comes my final posting....i would love to get your advice. also if you would delve a little deeper in explaining to me the philosophy behind the subsonic 'hard knee curve' and its integration with the main speakers, i would be most grateful. from my viewpoint, the hard knee curve is designed to give the sound a more dynamic effect but after adding the mains doesn't one lose the dynamic effect one worked so hard to attain? or is the effect still present even though the graphing of the effect changes?


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## thebuffman (Feb 4, 2009)

here are the graphs. the first graph is with the fbd in bypass mode so that you can see the non-equalized room. the second graph is with the fbd in full affect applying all filters.

*Raw state* (non-equalized) without smoothing








*Equalized* without smoothing








This is the *Full Spectrum* 0-1khz smoothed at 1/3 octave


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## brucek (Apr 11, 2006)

> unfortunately i do not have variable phase control. i can only set it for 180 or 0.


Yes, you do have a variable phase control. Simply use the distance trim in the receiver for the sub.

brucek


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## thebuffman (Feb 4, 2009)

brucek said:


> Yes, you do have a variable phase control. Simply use the distance trim in the receiver for the sub.
> 
> brucek


brucek can you elaborate more on this work around? i have placed the distance of my speakers and subs in the configuration menu of the receiver already. for the dual subs i added the distances and divided by 2 to get the average (not certain if this is proper or not). 

also i would love to hear your comments on my last posted graphs. thanks!


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## brucek (Apr 11, 2006)

> can you elaborate more on this work around?


It's not really a workaround. The digital delay in the receiver basically offers a pure phase delay, just as a phase control attempts to do. The phase control (if done correctly) is an all pass filter that acts as a delay that remains linear over its range. So, the time delay and phase control are a near proxy for each other.



> for the dual subs i added the distances and divided by 2 to get the average (not certain if this is proper or not).


It's not proper, but then there is no proper solution for two or more subs that aren't co-located. That's why you should co-locate them (or use a separate phase control on each).



> hear your comments on my last posted graphs


They look fine to me. Once you've taken care of all the obvious peaks and dips (as you have), then it's just individual taste...

brucek


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## thebuffman (Feb 4, 2009)

thanks for your input brucek! it is much appreciated.


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## Wayne A. Pflughaupt (Apr 13, 2006)

thebuffman said:


> how did you notice that i had dropped the subs' level down? and what is an appropriate level to set them at?


It’s basic house curve theory: Most systems sound best with the bass level louder than the mains. It was easy to see on your graph that the overall sub level was only slightly above the mains level (at least what we could see of them up to 200 Hz).



> i know the general answer is "whatever sounds good to me" but is there a general rule of thought?


Well, supposedly you can use REW for this, but I personally don’t know how that would be done – maybe someone else can comment. IIR AVIA, Video Essentials etc. typically recommend the sub to be about 10 dB hotter than the mains (measured with an SPL meter set to C weighting). However, I’ve usually set the subs by ear, ‘cause I trust mine.  

If you want to give the “by ear” method” a shot, what you might do is get a CD that you know has a good average level of bass – i.e., not one that you’ve always felt had weak or overpowering bass. Start with the sub turned down, then slowly turn it up until you hear it “round out” or “fill in” the lower registers that the mains aren’t getting ( you might want to have a helper lend a hand with this with you at the listening position). That’ll get you in the ballpark. Just live with that for a while and listen to other CDs to get a feel for things. If most everything else you feed your CD player seems bass heavy, or weak, make an adjustment (you might try the Basia CD I’ve recommended in my articles). Beyond this, I’ve found that movie bass can vary drastically, while TV shows are usually on the “bass shy” side. 

If you prefer something a bit more “concrete,” start with the 10-dB-hot thing the test discs recommend and go from there. However, I think they defer to what’s proper for movies, so you may find it a tad heavy for musikc.



> also if you would delve a little deeper in explaining to me the philosophy behind the subsonic 'hard knee curve' and its integration with the main speakers, i would be most grateful. from my viewpoint, the hard knee curve is designed to give the sound a more dynamic effect but after adding the mains doesn't one lose the dynamic effect one worked so hard to attain? or is the effect still present even though the graphing of the effect changes?


The hard knee curve is merely designed to reduce mid-bass “bloat,” making bass sound deeper. Not unnaturally deeper, IMO – the excessive mid-bass you can get from a regular house curve forces you to use a sub setting that diminishes the lower bass – at least for music. It has nothing to do with dynamics, which basically is greater “impact” or span between quiet and loud passages (check out an explosive scene with the receiver in the night viewing setting to see what I’m talking about).

As far as blending with the mains, it’s no different than what I described above.

Hope this helps.

Regards,
Wayne


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