Massive dip from 40-80 he

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loganschleich17

Audioholic Intern
Ratings
2
#1
Hey,
I have a massive dip in my new apartment. Depending on where I put the cross over it can be any where from a 10-20db dip between 40-80hz. I’m looking some forms promo treatment plans. I’ve added pictures of my room and of the FR graph.
The blue is crossover at 80, orange is at 100 green at 120.
Also that blue 2 seat side couch was moved out for measurements and leaves today so please ignore it
Any help would be appreciated



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loganschleich17

Audioholic Intern
Ratings
2
#2
I should also add that these measurements were taken at 85db and with Audyssey off


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highfigh

highfigh

Audioholic Overlord
Ratings
2,991 9 12
#3
Symmetry is your friend, or it would be if your room was symmetrical. Turn the balance control to either side and you should see this change, drastically.

The difference in first reflection times can cause this.
 
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loganschleich17

Audioholic Intern
Ratings
2
#4
Symmetry is your friend, or it would be if your room was symmetrical. Turn the balance control to either side and you should see this change, drastically.

The difference in first reflection times can cause this.
Yea I’ve identified some first reflection points and am going to buy curtains soon because for the L it’s the window. I was reading and was wondering if the rear wall could be partially at fault as well


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highfigh

highfigh

Audioholic Overlord
Ratings
2,991 9 12
#5
Yea I’ve identified some first reflection points and am going to buy curtains soon because for the L it’s the window. I was reading and was wondering if the rear wall could be partially at fault as well


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Unless they're extremely heavy, curtains won't do anything for low frequency issues. I had some leftover absorption panels from a theater build, so I tried them- they did the job, although they don't look great. 2' x 4' panels, with 2" and 4" of Corning 703 fiberglass, glued to 1/4" pegboard and covered with off-white muslin fabric is what I used. You can use any fabric that you an see through easily. The pegboard allows energy to pass through, reflect on the back surface and try to pass through again. Foam corner bass traps may work, but the wavelength of the higher frequencies is longer than the traps are wide, so they won't do much.

I ran Room EQ Wizard as I placed the panels and watched as they did their thing until I was satisfied.

As far as the rear wall, the room' dimensions WILL cause standing waves and if you use a room mode calculator, you'll probably see that several are stacked at the frequencies that are causing the most problems- remember- sound reflects in three dimensions, so length, width and height make a difference, as do the ratios between them.
 
Swerd

Swerd

Audioholic Spartan
Ratings
4,682 11 6
#6
That 'massive dip' sure looks like floor bounce. Everyone with a floor has it. Don't worry about it, and any effort at correcting it runs the risk of 'sucking the life out of your speakers' (to use a technical term).

Try retesting after moving your microphone further away or closer to the speakers. If the frequency of that dip changes with microphone placement, that makes it certain it's floor bounce.
 
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loganschleich17

Audioholic Intern
Ratings
2
#7
That 'massive dip' sure looks like floor bounce. Everyone with a floor has it. Don't worry about it, and any effort at correcting it runs the risk of 'sucking the life out of your speakers' (to use a technical term).

Try retesting after moving your microphone further away or closer to the speakers. If the frequency of that dip changes with microphone placement, that makes it certain it's floor bounce.
I did a lot of moving subs and then the mic and it got better when as I got closer to the speakers so that means floor bounce? Bs part is that the it got better 7 feet from speakers and that would look awful when I have a 17’ long living room being that close to the speakers lol


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shadyJ

Speaker of the House
Ratings
4,294 33 17
#8
Symmetry with regards to subwoofer placement is most certainly not your friend. That dip is too low in frequency to be floor bounce. This is an axial room mode, because, with respect to the length of your room, the subs are in the same place. Move one of the subs to a different lengthwise distance placement in your room. Try a sidewall or rear wall placement, or maybe even a near-field placement.
 
ryanosaur

ryanosaur

Audioholic Field Marshall
Ratings
891
#9
@loganschleich17
Have you done your crawl yet? ;) That’s pretty much the same advice from Shady.
Would love to hear about your results from crawling out your subs! ;)
 
Verdinut

Verdinut

Audioholic Field Marshall
Ratings
721 6 27
#10
Symmetry with regards to subwoofer placement is most certainly not your friend. That dip is too low in frequency to be floor bounce. This is an axial room mode, because, with respect to the length of your room, the subs are in the same place. Move one of the subs to a different lengthwise distance placement in your room. Try a sidewall or rear wall placement, or maybe even a near-field placement.
On the response curve, the sub crossover is set at 80 Hz. How about an out of phase situation between subwoofers and main speakers?
 
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Swerd

Swerd

Audioholic Spartan
Ratings
4,682 11 6
#11
On the response curve, the sub crossover is set at 80 Hz. How about an out of phase situation between subwoofers and main speakers?
Certainly possible and easy to put to a test. Compare measurements before & after switching the polarity of the sub woofer.
 
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loganschleich17

Audioholic Intern
Ratings
2
#12
Symmetry with regards to subwoofer placement is most certainly not your friend. That dip is too low in frequency to be floor bounce. This is an axial room mode, because, with respect to the length of your room, the subs are in the same place. Move one of the subs to a different lengthwise distance placement in your room. Try a sidewall or rear wall placement, or maybe even a near-field placement.
I have thought a lot about doing it but i read I shouldn’t because my avr (denon 1400h) needs the subs to be equidistant because it can’t calibrate them separately. Is there a way around that?


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loganschleich17

Audioholic Intern
Ratings
2
#13
Certainly possible and easy to put to a test. Compare measurements before & after switching the polarity of the sub woofer.
I did that this morning . The results were better with it at 0 the way it was for both of them


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ryanosaur

ryanosaur

Audioholic Field Marshall
Ratings
891
#14
Get ready to upgrade your AVR... :p
Then, plug one in and calibrate. Note the level settings for it. Run calibration for the second placement, note calibration settings. Plug them both in and adjust manually to fit. I used audyssey to set my distance and levels, but otherwise have turned it off. If you can keep them somehat eqiditant from you, the delay will wash out. You can adjust gain to match on the sub. :)
 
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loganschleich17

Audioholic Intern
Ratings
2
#15
I ran REW for 4 hours today. Did a lot of combination of things. Bottom line, having 2 subs up front is pointless because I’m getting almost the same response from one being up there alone ( right was better). But idk how I can make this work when the information tells me I need a avr with xt 32 for my subs to be anywhere but equidistance. That’s my situation. Thanks for the replies and help I just feel like I wasn’t being clear enough.


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loganschleich17

Audioholic Intern
Ratings
2
#16
For real thank you for your replies because those guys on rew set up on avs don’t reply to anything unless they know you and graph perfectly lol. I waited a week


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loganschleich17

Audioholic Intern
Ratings
2
#18
Get ready to upgrade your AVR... :p
Then, plug one in and calibrate. Note the level settings for it. Run calibration for the second placement, note calibration settings. Plug them both in and adjust manually to fit. I used audyssey to set my distance and levels, but otherwise have turned it off. If you can keep them somehat eqiditant from you, the delay will wash out. You can adjust gain to match on the sub. :)[/QUOTThats a good idea, but how will that work if in levels and sdistance my avr treats the 2 subs as one


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loganschleich17

Audioholic Intern
Ratings
2
#19
Get ready to upgrade your AVR... :p
Then, plug one in and calibrate. Note the level settings for it. Run calibration for the second placement, note calibration settings. Plug them both in and adjust manually to fit. I used audyssey to set my distance and levels, but otherwise have turned it off. If you can keep them somehat eqiditant from you, the delay will wash out. You can adjust gain to match on the sub. :)
That’s very clever Ryan but how can I enter them but I can’t enter 2 values for subs my avr treats them as one


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loganschleich17

Audioholic Intern
Ratings
2
#20
REW with minidsp would allow you to do that, I believe.
The takeaway today was as I moved my couch forward the dip lessened . But I cannot sit 6-7 ft away from the tv and have 11 ft behind me. Also I kept one sub flanking the CC to one side for every measurement and moved the 2nd around and it seemed to make little to a small difference in the results. Today was discouraging because I tried putting the 2nd sub several places and it didn’t change much. The true change was being 6 feet from the tv lol. The dip went from -20 9.5 ft away to -2 6 feet away


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