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Discussion Starter · #1 ·
Looking for some insight about the room response of my MFW-15s.


I took some measurements and got the following results:



Let me first mention that my room is not sealed. The left wall is a pony wall and looks down into our great room. Hence, the different response from the two MFWs. They are each placed in the front corners of the room. Here is an old drawing of the room that shows tower fronts in the corners. I no longer have those. The subs are now in the corners and I have bookshelf fronts above the subs. I have built a new rack that is longer and fills the space between the subs.


Long story short-the subs are not moving to a different spot.


As seen in the above graphs, the subs behave very differently from about 50-110 Hz. Would adjusting the phase on one of the subs or the distance in my prepro help to flatten the nulls? Or do I need some kind of EQ?

Im gonna play around with stuff tonight, but I thought I would throw it out there beforehand.
 

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Quote:
Originally Posted by FoSheezy /forum/post/18280857


Would adjusting the phase on one of the subs or the distance in my prepro help to flatten this null?


Im gonna play around with stuff tonight, but I thought I would throw it out

there beforehand.

Yes. Try that first as it will be the cheapest. You graph is a little hard to see but EQ would also help out in the lower region.
 

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Your graph is hard to see but it looks like the Y axis is 5dB increments and therefore have a >20dB spread for the summed signal. You say you can't move the subs but I'd try moving them slightly. Even a few inches can make a difference. Combined with adjusting the phase you should get a better response. You're fighting some serious room issues and it's a dangerous game boosting the nulls and shouldn't boost more than a few dB. You're demanding much more from the sub and are risking over-excursion/over-driving
 

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*need*? certainly not. did you need 2 MFWs? nope...but the 2nd sure sounds better, yes?


same here. the eq will absolutely help you tune the sound. most use them to flatten response, some to build a 'house curve' which may not be textbook 'correct', but sounds better to them.


you can move the subs, and/or play with the phase for free. this can help, but is a whole lot of trial and error and may still not achive what you want given the confines of acceptable placement.


or, you can eq. as has been said, cut the peaks and don't boost the nulls. fix them with relocation and/or phase.


if you elect to eq, consider that most eqs cannot adjust two subs independently (SVS/audyssey as-eq1 comes to mind as one that can, for ~$700). not the end of the world since they reproduce the same signal, but highly desireable if they reproduce that signal from two different locations as yours do.
 

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I’d certainly recommend equalization. However, boosting or cutting is academic. Any equalization will ultimately tax headroom, so you have to have headroom to spare going in. With two of those subs in the room, I doubt headroom will be an issue. It’s true that nulls can’t be equalized, but not all depressions in response are nulls. Nulls are easily recognized, typically they are very narrow and deep, not broad like what you have. Broad depressions usually respond well to equalization. Your best bet would be to equalize the combined output of the pair as a whole, rather than separately. That usually works better.


Regards,

Wayne A. Pflughaupt
 

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Discussion Starter · #6 ·
I just updated the graph. The last one was pretty blurry and I made some adjustments to better level-match the subs.

I still need to play with phasing, etc.
 

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Quote:
Originally Posted by Wayne A. Pflughaupt /forum/post/18299255

Nulls are easily recognized, typically they are very narrow and deep, not broad like what you have. Broad depressions usually respond well to equalization.

Are these "broad depressions" location specific?


For example, I'd expect a null to appear in a room based on, say, a room mode, so I might expect a certain frequency to be absent at a specific location, but moving to either side of the null location would improve the reception of that frequency. Would these broad depressions also exist in a specific location in a room, and moving from side to side around the depression would improve those frequencies? Or do the broad depressions typically manifest throughout the entire room?
 

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Okay, thanks.


I'm having some weird problems with some low frequencies I don't expect to have problems with. After you brought up the wide full octave depression, I thought maybe there was a window of opportunity for my problem to be instantly resolved, but it appears it is going to be more involved.


I'll start a new thread for myself this weekend, when I've collected some data about my asymmetrical frequency void. I don't want to hijack this thread any more than I have. Apologies to the OP.
 

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First thing I did in a similar loft-style room was to put in the remaining walls (including taking the pony wall all the way up) to make it an enclosed room. Not only did it help normalize the response but one can watch a movie and not interfere with sound levels in the rest of the house. From your drawing, looks like it would be pretty easy to do...


John
 

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Discussion Starter · #11 ·

Quote:
Originally Posted by John Robert /forum/post/18349453


First thing I did in a similar loft-style room was to put in the remaining walls (including taking the pony wall all the way up) to make it an enclosed room. Not only did it help normalize the response but one can watch a movie and not interfere with sound levels in the rest of the house. From your drawing, looks like it would be pretty easy to do...


John

That's definately something to consider. I just dont know if I could convince the wife.
 
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