# Got my BFD 1124 working... but, is it doing "enough"?? Look at my graphs please>>



## deepstang (Nov 17, 2009)

Thanks to Wayne and others, I have all my basic questions answered and was able to spend a lot of time trying different numbers. Let me start posting some graphs. I have dual Epik Sentinels in a family room with an Onkyo with NO sub processing.

It seems that a filter was sent to the BFD @ 100Hz; however, there was NO gain number?? When I tried different house curves sometimes it would send a filter for a +10db boost at 20hz; however, that "boost" lowered the curve around the 20-25Hz range. ???

Here is my base REW graph before any BFD filters:









This is the graph AFTER the BFD applied 4 filters for a flat response:









This is the graph after a "house curve" is applied and only 1 filter was applied (@80Hz):









After trying multiple house curves, the numbers/filters applied don't really make sense...and upon testing those graphs, the results were only some where between the 2 graphs above. 

I am not able to create any type of "knee bump" curve in my room REW graph regardless of any points I enter in the House Curve. The 20Hz +6db gain worked best as seen in the graph above; however, nothing else worked.

I REALLY want to be able to have a spike in my graph around 40Hz. I have tried a 2 point "interpolation" house curve (40 15 80 0), but it did not apply anything significant to bring it to such a house curve.


Don't laugh, but the best sound/tune I enjoyed in this room was from an old Velodyne that was VERY limited according to REW; however, it yielded the best sound (to me) for HT.  Even my wife liked the small Velodyne compared to the multiple "upgrades". I know that our ears got used to the spiked curve of the Velo....but it, it sounded great. Here is that old graph:


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

deepstang said:


> This is the graph after a "house curve" is applied and only 1 filter was applied (@80Hz):


Your house curve looks pretty strange. It appears to run only between 60-20 Hz? The other problem is that response isn’t tracking the house curve Target at all. You can’t get the needed downward slope of the upper frequencies if they keep going in a virtual flat line above the Target.

And there’s no shelving at the lower end either.

Basically, your response after equalization needs to track the Target pretty hard, something like this:


















If you can’t get REW to do it automatically, you can try manually tweaking the filters by fiddling with the settings shown the EQ Panel. REW will show you the predicted response of your filter adjustments.

Did you do the upper and lower sine wave tones test as outlined in the house curve articles, to determine exactly how much of a slope you need? You’ll never be happy with the results of a house curve without this critical starting point.

Yes, I expect that you like the Velodyn because you were used to it. However, if you get the proper curve dialed in and spend a few weeks listening to it, you probably won’t go back to the Velo.

Regards,
Wayne


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## deepstang (Nov 17, 2009)

Thanks Wayne. Wow you have done an amazing job on this write up on House Curves:

http://www.hometheatershack.com/for...els-hard-knee-house-curve-long.html#post55647

I am still reading and processing it. This is a very detailed process. The house curve application is not as straight forward as I thought. I have tried MULTIPLE target curves; however, the real results never follow the target curves that I set (via the House Curve tab and my *.txt file). 

I saw your recommendations above about "no shelving" at the lower end, and running an upper and lower sine wave test tone. Honestly....I have no idea what any of that means, but I am desperately reading to figure it out. I don't want to sound lazy, but I was really hoping that setting the target curve in the Home Curve tab would do the trick. As I said, I am still trying to chew through that link and figure out how you got your response to follow your Target Curve so well.

Oh wait....i just got to the "*Tips for those who use REW’s auto-equalizing function*" section, and it looks like I can chew on this one a little better. I love the in-your-face reality coments that keeps us focused on what REW and the DSP is all about. GREAT STUFF!!


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

> I saw your recommendations above about "no shelving" at the lower end, and running an upper and lower sine wave test tone. Honestly....I have no idea what any of that means…


I think you mean “shelving,” not “no shelving?” “Shelved” means that you stop the house curve rise at a certain point, and level off response below that point, instead of maintaining the rise all the way to the sub’s lowest extension.









*Shelved House Curve








Non-Shelved House Curve*​



> ...and figure out how you got your response to follow your Target Curve so well.


I re-align the Target to a good mid-way point between the unequalized peaks and valleys, then set the filters manually to track the Target.

Regards,
Wayne


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## deepstang (Nov 17, 2009)

Wayne, I finally had the pleasure of going through that whole article. 75 dB happens to be about the half way "target" of my peaks and troughs. I also loaded the Wayne House Curve (as I like to call it ) :

30 6.0
35 4.4
40 3.1
45 2.0
50 1.1
60 -0.1
70 -0.6
80 -0.5
90 0.0

My confusion comes in because it seems that REW does not even attempt to follow the specified "house curve". When I click "Find Peaks", it only finds one peak....and when implemented, it just basically smoothes out the end of my graph (10.1db @ 73Hz). That same single peak is found with and without the 1/3 smoothening. Here is that graph without any BFD filters specified (but with 1/3 smoothening)....but with the Wayne House curve loaded:


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

REW will only recommend filters for peaks that are above the Target Curve. The house curve bumped the curve up 6 dB when it was loaded. Move the Target back down to 74 dB and run the Find Peaks function again. In the end you'll probably have to tweak the filters manually. In the two examples I showed in Post #2, both were equalized manually, not using the auto EQ function at all.

Regards,
Wayne


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## goonstopher (Mar 2, 2009)

Sorry to butt in here but, if he liked the mid.low bass hump then why would such a low target curve be advisable?

I understand that the ear is less sensitive to lower bass but if it doesn't fit someones tastes then why bother?


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## deepstang (Nov 17, 2009)

Hey goonstopher....good to see you around!! Wayne, I started manually adjusting the Eq filters, and that resulted in a better graph from REW (in terms of adhering to the Wayne House Slope). 

Goonstopher knows my story well. I basically really enjoyed an older Velodyne that had a huge hump around the 38 Hz area. These so called "upgrade" subs often yielded dissapointment to my ears due to my trained preference of that hump. I have been wisely recommended to emulate that hump to re-gain that satisfaction I had. 

Now that I am manually applying these filters I may do that. BTW, the numbers that I can manually adjust to the right of the Eq are what actually get sent to the BFD, right? Those green numbers simply tell you how much of a deviation there is from that line?


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

goonstopher said:


> Sorry to butt in here but, if he liked the mid.low bass hump then why would such a low target curve be advisable? I understand that the ear is less sensitive to lower bass but if it doesn't fit someones tastes then why bother?


 Well for starters, his current sub doesn’t seem to have that 40 Hz peak. If he can get the sub equalized for something “reasonably proper” and doesn’t like it after spending some time with it, he can always artificially add a 40 Hz peak with the equalizer.

Regards,
Wayne


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

deepstang said:


> BTW, the numbers that I can manually adjust to the right of the Eq are what actually get sent to the BFD, right?


Yes, assuming you have the MIDI connection, AFAIK REW can send manual filters to the BFD (I’ve never used the MIDI function personally).



> Those green numbers simply tell you how much of a deviation there is from that line?


 The green numbers (i.e. 25 +7) are the values for the BFD’s frequency setting. E.g. “25” entered with the “Frequency” button, “+7” entered with the “Fine” button. In the EQ Panel, the “Frequency” window tells you the actual frequency that “25 +7” is: 27.28 Hz.

Regards,
Wayne


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## deepstang (Nov 17, 2009)

WOW, what a world of difference. Things sound a little boomy and not as crisp as I would like, but have finally regained the sound I have been looking for since moving away from my Velodyne!!!! This is a huge move forward as I have spent months and literally multiple ID subs trying to get here. 

Here is the graph with my manually adjusting/applying filters to my BFD to create the Wayne house curve:









Here is the graph with the forced 38Hz hump:









That 38Hz hump created the missing sound I was perceiving for over 6 months....since "upgrading" from the Velodyne to initially the SVS PC12+, and than the dual Epiks.


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## robbo266317 (Sep 22, 2008)

This is purely my personal opinion so please treat it as such.

I would turn the 38 Hz hump down by ½-1 dB per month until it is back to flat and see if you get to enjoy a flatter sound over a period of 8 months or so.

Just my thoughts.


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## deepstang (Nov 17, 2009)

Yeah, I think my ears have already fallen OUT of love with that large 38 Hz spike; however, beefing up that 25-35Hz area was a must for my satisfaction. 

My other question is with the INPUT level from the AVR to the BFD. I know per instructions, we are to set the right input level going to the BFD and than only change the gain at the subs. That is a pain if you have dual subs. After this last set of filters I noticed that the subs are 5dbs louder. I want to turn it down, but because the subs are not equidistant this becomes a pain.

What happens if I turn down the gain from the AVR. I know that the EQ leds on the left side may not go as high...but does that really affect the operation and filters of the subs and BFD??


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

Nope - the input level has no effect on the BFD's operation.

Regards,
Wayne


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## deepstang (Nov 17, 2009)

Wow, thanks Wayne! This is what I read on the BFD Guide that made me think that:

*Remember not to adjust the volume of your sub via your pre/pro or receiver after you have set the input level... use you sub volume or the volume on the amp connected to your sub, which should be inline after the BFD. *

Found on the "Setting the Input Levels" section (towards bottom):
http://www.hometheatershack.com/forums/bfdguide/

BTW, I also noticed that my SPL meter is acting crazy. With barely any background noise in the room, the SPL reading in REW is close to 70db!! Before, I would have to really crank up the AVR to get to that. I tried turning the meter on and off, and testing the battery. When I unplug the wire to the SPL meter, the SPLs (for calibration) on REW goes back down. Is my RatShack meter defective? I have read how strongly HTS wants us to use a properly calibrated mic (or Galaxy). Maybe I will go swap it out.

Thanks!


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

> This is what I read on the BFD Guide that made me think that:


Yeah - I feel there is some erroneous information in that section. Even after you set the sub levels, they are going to change with your main volume control, and even with the bass levels of the program material. So, no reason to sweat having to change the sub output level, if you need to for some reason.

BTW, you say it’s a pain to do separate adjustments for your subs at the subs – are you saying your receiver has two sub outputs, with separate level adjustments for each?




> BTW, I also noticed that my SPL meter is acting crazy. With barely any background noise in the room, the SPL reading in REW is close to 70db!!


Keep in mind that the SPL meter is self is C-weighted, which had a bass roll out below 40 Hz. And we’re using a calibration file, to essentially flatten the meter’s response below 40 Hz. So, the REW meter is going to register ultra-low frequency noise (below 40 Hz) much more so than the meter’s read out would. Air conditioners, furnaces, some source outside your home, etc. – there are many sources for low-freq noise that could account for what you’re seeing on the REW meter.

Regards,
Wayne


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## deepstang (Nov 17, 2009)

So, just double checking before I make the adjustment.....reducing the output from the AVR to the BFD will not negatively affect anything that the BFD is doing (besides of course turning down the LFE level).



Wayne A. Pflughaupt said:


> Yeah - I feel there is some erroneous information in that section. Even after you set the sub levels, they are going to change with your main volume control, and even with the bass levels of the program material. So, no reason to sweat having to change the sub output level, if you need to for some reason.
> 
> BTW, you say it’s a pain to do separate adjustments for your subs at the subs – are you saying your receiver has two sub outputs, with separate level adjustments for each?


+1. I think that the BFD Guide is awesome; however, it has a lot of erroneous information. I also don't like having REW search for peaks up to 150-200Hz, like the BFD Guide states. I think your advice of limiting the Peak filters to the crossover frequency is best.

No, my Onkyo 605 only has 1 LFE out; however, I have NON-co-located subs that require different gains to achieve the same SPL at the listening position. The Epik knob is VERY sensitive and requires a lot of light massaging to equally level match them (of course at the sub).




> Keep in mind that the SPL meter is self is C-weighted, which had a bass roll out below 40 Hz. And we’re using a calibration file, to essentially flatten the meter’s response below 40 Hz. So, the REW meter is going to register ultra-low frequency noise (below 40 Hz) much more so than the meter’s read out would. Air conditioners, furnaces, some source outside your home, etc. – there are many sources for low-freq noise that could account for what you’re seeing on the REW meter.
> 
> Regards,
> Wayne


Thanks Wayne. Before the meter seemed to be a lot more sensitive. Also, it seems that what the needle reads on the SPL meter and what REW reads is very different. I will have to test this further to confirm. It is "registering" at very different levels as before with the same sound conditions within the environment.


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