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Measurements - what to do next

brk

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Hello room acoustics wizards,

After some time measuring and working with REW I have managed to get meaningful improvements in the measurements and subjective sound of my two-way speakers- see attached. Space limitations require set up along the long wall of a 22 x 14 foot room, so they are only two feet from the back wall and about 10 feet from me. Within limitations, moving them around does not help these measurements very much. The attached responses represent averages taken from four positions around my left ear location using a UMIK and a fixed stand (the right speaker looks very similar). Note that some of the bass EQ strategy is intended to mimic the analog EQ box that originally came with the speakers (boost at 35 hz plus a subsonic filter),

1. Would a subwoofer help? (possibly add deep extension and fill in a touch more around 80hz)
2. Ever since seeing that ugly 100-300 hz region I stayed away from it and do not EQ. Is this correct?

Thanks very much,

Bryan
 

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First I would try to force-correct that dip between 80 and 400Hz to see if your amp can tolerate the compensation and if there is increased ringing that might or might not be disturbing for you (you can measure that with the Waterfall and RT60 diagrams)
One sub could help but depends on the positioning in the room
The same goes for multiple subs - those will definitely help when placed correctly
You can use the Room Sim tool in REW for the above points
 
My first inclination is not to EQ yet, but to figure out what is the cause of the huge cavernous dip. Take the speakers outdoors to measure… or measure the drivers nearfield etc. Find some way to figure out what is the actual freq response of the speakers without the room.
 
That dip is very wide and at a higher frequency than one would normally expect -- it is normal to have narrow alternating peaks and throughs with 20-25db difference, but this is too wide and consistently depressed signal level. I am not sure what can possibly cause that, and a subwoofer is unlikely to fill anything between 200-400 Hz.

You can try to lower your target curve, say by 5-6 db, and get flatter response at the expense of peak SPL.
 
Hello room acoustics wizards,

After some time measuring and working with REW I have managed to get meaningful improvements in the measurements and subjective sound of my two-way speakers- see attached. Space limitations require set up along the long wall of a 22 x 14 foot room, so they are only two feet from the back wall and about 10 feet from me. Within limitations, moving them around does not help these measurements very much. The attached responses represent averages taken from four positions around my left ear location using a UMIK and a fixed stand (the right speaker looks very similar). Note that some of the bass EQ strategy is intended to mimic the analog EQ box that originally came with the speakers (boost at 35 hz plus a subsonic filter),

1. Would a subwoofer help? (possibly add deep extension and fill in a touch more around 80hz)
2. Ever since seeing that ugly 100-300 hz region I stayed away from it and do not EQ. Is this correct?

Thanks very much,

Bryan
you must measured each speaker no the both in the same time.

 
Your measurement actually resembles the left rear channel in my own multichannel 7.1 desk setup:

1666296194420.png 1666296209292.png 1666296213953.png 1666296217911.png 1666298137321.png
*wavelet could be better, but space for any more acoustic treatment is just not possible at the moment.

The speaker in question is a (modded/sealed JBL LSR305) that's facing off-axis at the opposite side-wall instead of the main desk listening position -- a very, very bad position wherein it's flanked by multiple nearby boundaries that simply was necessary for certain reasons. This is about the "worst" speaker channel I have in this mch setup. However, the "power response" of the speaker is actually quite flat if measurements are averaged across multiple positions throughout the room.

My "base equalization" from the default native response made the speaker sound a whole lot better when A/B compared with the rest of the other hodgepodge of studio monitors in my listening room.

The main reason I didn't try to fill-in more of the very visible wide FR cavern was to avoid making the speaker sound worse due to increasing distortion and resonances -- both measurable and audible.

Assuming you are able to get a reasonably good response at the MLP from your supposed future sub(s), and can xo high (perhaps aided with the help of DSP and room treatment), one should be able to at least "improve" or "salvage" somewhat the seen measured deficiency caused by bad room positioning, geometry or acoustics -- now, only up to a point!
 
Wow - thanks for all of these replies.

Rednexala - you have correctly identified the speakers based on only the in-room frequency response- like a DNA fingerprint. Impressive!

Ppataki - when you say "force correct the dip between 80 and 400" do you mean adding a wide EQ boost there - would need like +6db at 200 with a Q of about 1.

Frgirard - yes, I measured each speaker individually, not at the same time. And they both look like this.

Am guessing from these responses that this is NOT normal behavior for a two-way speaker? I thought dips and troughs were common there due to floor bounce. They SEEM to be set up correctly - 6 feet apart, 10 feet from the couch, and pointed at my ears. I could try moving the coffee table but suspect that is not the issue. Have thought about taking them outside but that would be a major effort.
 
Have thought about taking them outside but that would be a major effort.
Isn’t all data you’d get from that (and more) already in the Stereophile measurements I linked to?
 
Sort of - that 800-1000 hz bump seen in anechoic measurements becomes larger and wider in my room at the listening position. This is easy to take out with EQ. The room naturally smoothes out the treble to give a roughly even 0.8 db/octave decline after 1K.

The 80-350 range is the problem. A smaller version of this issue appears in the anechoic measurements, but it is larger and more uneven in my room. According to REW, there are phase shifts around 80 and 300- these have scared me away from any EQ in that area.
 
merlin_correct_stereophile.png


Edit: quickie in Paint.NET. Not 100% sure about the alignment. The overlay could have been a fraction more up maybe. Added the source files for you or anyone to play with it further.
 

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they are only two feet from the back wall
This might be just the same distance as the midwoofer-floor one. Could you be suffering from a combined SBIR + floor bounce effect?
 
Measurements here using RTA / periodic pink noise. These are averages from several positions around each ear using UMIK on a stand - about 100 averages each (measurements were generally similar to one another).
 

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Measurements here using RTA / periodic pink noise. These are averages from several positions around each ear using UMIK on a stand - about 100 averages each (measurements were generally similar to one another).

Could you do a single sweep from the listening position please?
 
Sweep - left only
 

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Could you try the moving microphone method?
 
Sweep - left only

After doing frequency dependent windowing it seems like there is a big early reflection happening at 800Hz, two PEQ filters easily adjust both issues. Experiment with the gain values using pink noise. I expect your room to sound tinny, nasal and forward. and the bass to feel a little bit disattached.

1666335217094.png
 
Moving mic - RTA - periodic pink noise. Left channel (right looks similar).

Why such a high Q value of 7 for the filter at 860?
 

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