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Hello Everyone,

First time poster here and need some help on implementing a house cure or a hard knee house curve. I've read
Wayne's tutorial on both many times but I'm having some trouble applying it in real life and having it sounding good. The speakers are a pair of DIY JBL M2's and the amplifier is a Crown DCI 4300N using the preset DSP from Crown for these speakers. I started out by taking measurements from three listening positions. At each position three measurements were taken with each left and right speaker. A total of 18 Reference Points were taken. Please see Picture 1 for the average.
Average.jpg
From here I used the recommended window Level of 130/20 from Wayne's House Curve Tutorial and raised the target
level to 77db. I received what's in Picture 2 with two parametric values of 56.20Hz and 32.30Hz. Should I be doing more smooth the dip at 240 and the rise at 600Hz? I tried some values for the 240 pint of interest and it sounded muffled and was wondering I was doing something wrong. I also read that Wayne's curve was around 16db from the low frequency to the high, but haven't even started to tackle this yet. The speaker crossover point is around 750Hz.
2.jpg
Picture 3 is the parameters for the calculated EQ. I have very little EQ experience and would really appreciate any help.
Capture3.JPG

Thank you,
Scott
 

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It’s good that you trusted your ears as to what sounded good instead of what might have looked good on a graph. :T

Yes, I think the 240 Hz depression should sound better if it’s addressed. However, it will be tricky as it’s an asymmetrical problem, meaning it is steeper on one side than the other, and equalizer filters are symmetrical. It will take at least 2-3 filters to address it. Just make sure the filters you use do not “spill over” beyond the frequencies where response dips below the Target (~175 Hz – 500 Hz). IOW, you don’t want to see frequencies below 175 Hz or above 500 Hz creeping above the Target line after equalization. The latter especially will only exaggerate the bump at 600 Hz, which won’t be a good thing.

The best you can expect with a problem like this is a general improvement in response, not perfection. The deepest spot (~220 Hz) looks to be down at least 8 dB, which is probably too much to try to fully correct.

As for as the 600 Hz bump, tough call. It’s not very wide. You can try some correction, but if you don’t notice an audible improvement I’d pass on it.

Regards,
Wayne

 

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I really appreciate the response Wayne. Looking at the raw data again it looks like my measurements taken from the left listening position with the right speaker appear to be lowering the average in the 70Hz-350Hz region(see red measurement in the graph below). The listening position distance between the Left and right is only around 3 feet. I think may I need play around with the real time pink noise feature and placement before using EQ, unless someone else has a better solution. Always open to suggestions.
Graph.jpg

Note: Black measurement is from Center Listening position, Blue is from the left Listening position, and Red is from the right Listening position. All taken using the right speaker.

Thanks,
Scott
 

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Agreeing with the good advice Wayne P. has already given, a couple of points:

Before deciding any coarse of action on a smoothed curve, it is wise to at least take a glance at the unsmoothed curve to see what is really going on. A depression in the curve like you are seeing at 240 is usually actually one or two sharp dips in frequency response, which you will not be able to do anything about, and which could give you some trouble if you try to.

Also, as Wayne P, suggests, trust your ears. My own preference is much closer to flat, which probably works better in a treated room, as mine is, but the point is if you think the slope looks a bit severe, be brave and make up YOUR OWN target curve and try again.

Third, your original measurements are worth taking a look at. How spread out are they? How big is your listening area? Is your average coverng several seats in a Home Theater setting, or all within a few inches of the head width near the main LP? If you measure over a wide area and average, then sit down to hear what the result sounds like at the LP, your measurements might not match what you hear.


Edit: I see you addressed this last point in our last post. Even a measured LP area 3 feet wide could be deceptive when you sit down to listen. Try averaging a few measurements just a little wider than the LP itself, get that area sounding good, then widen your measurement area to see if further adjustments are warranted. My own belief is that, 99.99% of the time, the only listener in the room who really cares about the sound is YOU, so make it sound good at your seat and ignore all the other seats, and see if anyone ever notices. If you ever have a serious listener visit, you are probably going to put him ih the hot seat anyway.
 

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Agreeing with the good advice Wayne P. has already given, a couple of points:

Before deciding any coarse of action on a smoothed curve, it is wise to at least take a glance at the unsmoothed curve to see what is really going on. A depression in the curve like you are seeing at 240 is usually actually one or two sharp dips in frequency response, which you will not be able to do anything about, and which could give you some trouble if you try to.

Also, as Wayne P, suggests, trust your ears. My own preference is much closer to flat, which probably works better in a treated room, as mine is, but the point is if you think the slope looks a bit severe, be brave and make up YOUR OWN target curve and try again.
Since these are DIY, my first thought was to swap left and right speakers and measure again to see if the dip follows. Making measurements without the preset DSP and then calculating my own parameters is a good suggestion and sometime I will try, hopefully this weekend if I don't have to work. DSP make things a whole lot cheaper when you want to experiment.

Third, your original measurements are worth taking a look at. How spread out are they? How big is your listening area? Is your average coverng several seats in a Home Theater setting, or all within a few inches of the head width near the main LP? If you measure over a wide area and average, then sit down to hear what the result sounds like at the LP, your measurements might not match what you hear.
The listening area is not huge, being 12'x20' with the 2 person love seat about 11' from the speakers. The room is split with audio on one side and the wife's sewing stuff on the other. The speakers are set up on the short side giving space behind the seat to provide an open area behind your head. A stereo console sized liquor cabinet is on the left of the seating position so the speakers are not exactly centered on the 12' wall. I'd say they are about 8' apart. I figured the seating position would at the most have two people, so the farthest point of measurement would be one persons left ear and the other listeners right ear.

Thanks for your help,
Scott
 

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Edit: My own belief is that, 99.99% of the time, the only listener in the room who really cares about the sound is YOU, so make it sound good at your seat and ignore all the other seats, and see if anyone ever notices. If you ever have a serious listener visit, you are probably going to put him in the hot seat anyway.
100% agree
 

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Since these are DIY, my first thought was to swap left and right speakers and measure again to see if the dip follows. Making measurements without the preset DSP and then calculating my own parameters is a good suggestion and sometime I will try, hopefully this weekend if I don't have to work. DSP make things a whole lot cheaper when you want to experiment.
It seems doubtful you would see a significant difference at that low frequency due to speaker difference.

The listening area is not huge, being 12'x20' with the 2 person love seat about 11' from the speakers. The room is split with audio on one side and the wife's sewing stuff on the other. The speakers are set up on the short side giving space behind the seat to provide an open area behind your head. A stereo console sized liquor cabinet is on the left of the seating position so the speakers are not exactly centered on the 12' wall. I'd say they are about 8' apart. I figured the seating position would at the most have two people, so the farthest point of measurement would be one persons left ear and the other listeners right ear.
Good plan on the love seat, I have thought of it myself but have not yet pulled the trigger. I will be looking for one without divided seat/back cushions so I can be comfortable in the middle when listening alone. Which is... all the time... So I am STILL back to a single LP in the center. Besides, you will only get the best soundstage & imaging in the CENTER position. That is just the way our psychoacoustical brains work.:T
 
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