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Discussion Starter · #1 · (Edited)
Hi everyone,

I have 3 10" subwoofers. 2 front and 1 behind MLP.

I get a Deep null at 80hz in stereo mode in REW. I can fix this by adjusting subwoofer distance or variable phase. But that induces more problems. I can't increase subwoofer distance due to limitations in Audessey as they are already at max.

Fronts only show a mild dip. Subwoofers only stable linear curve from 20 - 120hz. Crossover at 110hz fix everything with the default Audessey distance settings.

What to do? Buy a minidsp, crossover 110hz? Tried to even things out in Multeq without success.

MLP is almost in middle of the room. Can't change this.
3121458


Thanks.
 

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Epson 5050,120' screen, AA towers/Horizon w Raals, SVS Subs, Pallisar seating
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A diagram of the room and sub locations would help.
 

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Discussion Starter · #4 ·
A diagram of the room and sub locations would help.
3121480


Here is a diagram of the room in metric.

Room:
Width: 3.85 meters
Lenght: 6.80 meters
Height: 2.35 meters

FL/FR are about 55 cm from side wall.
C in the middle.
Front subs 95 cm from side wall (1/4)
Back sub 170 cm from right wall.
 

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How close together are the two subs on the front stage? I suspect they are "coupling". Also, long standing waves can often be tamed using odd (1/3, 3/5) placement intervals.

Personally I'd try a couple of quick changes to see if things improve. I'd try one sub in the front right corner of the room, move the rear sub to the left rear corner of the room, and place the third one at 1/3 distance from the front wall on either the left or right long wall and see what you get. If you get too much boomie gain from corner placement, move them towards the center either 3/5 or 1/3 the wall length and try again

I'd also try doing a sub craw to find the 1st and 2nd optimal positions in the room using a single sub then place a sub in each of those positions then placing the third sub at an unequal distance (1/3 or 3/5) from the 1st two.

Hope that helps, Good luck
 

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Front wall placement of two subs is typically optimized with the subs centered at the 1/4 and 3/4 points of the width of the room.
 

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Discussion Starter · #7 ·
How close together are the two subs on the front stage? I suspect they are "coupling". Also, long standing waves can often be tamed using odd (1/3, 3/5) placement intervals.

Personally I'd try a couple of quick changes to see if things improve. I'd try one sub in the front right corner of the room, move the rear sub to the left rear corner of the room, and place the third one at 1/3 distance from the front wall on either the left or right long wall and see what you get. If you get too much boomie gain from corner placement, move them towards the center either 3/5 or 1/3 the wall length and try again

I'd also try doing a sub craw to find the 1st and 2nd optimal positions in the room using a single sub then place a sub in each of those positions then placing the third sub at an unequal distance (1/3 or 3/5) from the 1st two.

Hope that helps, Good luck
The two subs are about 2 meters distance from each other. After numerous different locations the two subs up front have given me the best response so far.

I can try a SUB in the front right corner. But that means that the two front subs will have different distance from MLP. They are connected through a Y-adapter.
But I get really bad low extention with the rear sub in the left rear corner for some reason.
 

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Sitting in the center of the room is usually a big nono due to high chance of null or peak at that position.


Sent from my iPad using Tapatalk
 

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That is exactly how they are placed.
Well, then ... try other positions in the room. There are no guarantees, as you have learned. Just keep trying other positions until you get it right. I would be a bit concerned that you are at your max distance that your receiver can handle. Try putting the subs closer to your seating position so you have some additional play. How about the exact middle point of each long wall?

You've chosen to try to integrate THREE subs into your system. That's not child's play! I would expect a long and arduous process to get to audio nirvana.
 

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Discussion Starter · #11 · (Edited)
Well, then ... try other positions in the room, as suggested by other posters. No guarantees, as you have learned. Just keep trying other positions until you get it right. I would be a bit concerned that you are at your max distance that your receiver can handle. Try putting the subs closer to your seating position so you have some additional play. How about the exact middle point of each long wall?

You've chosen to try to integrate THREE subs into your system. That's not child's play! I would expect a long and arduous process to get to audio nirvana.
I agree. It's a Marantz SR7013. All three subs are XTZ 10.17 Edge with PEQ. Internal delay is an issue. Even with PEQ off.

Middle point of each side wall is not possible due to the size of the couch vs room width.

Three subs are not easy to integrate! Tell me about it 😋 Also have the WAF and her on my back!
 

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That is exactly how they are placed.
With the front two subs 2 meters apart I no longer suspect coupling of the front two subs.
The rectangular proportions of the room will make a difference as to whether 1/3 and 2/3 or 1/4 and 3/4 placement on the front wall work best. Try with subs centered at 1/3 and 2/3 the front wall width and try doing a sub crawl for the rear sub.

Sometimes square and rectangular rooms with proportional floor to ceiling heights are the hardest. Think of it as continuous predictibly rebounding waves in a bath tub or swimming pool. With long LF waves, odd rather than equal distances are your friend. If you can't move your front soundstange further into the room or you can't move your seating forward or backward away from center perhaps you can move them both towards each other enough to get better response. Good Luck.
 

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Time aligning and gain matching with something like a MiniDSP 2x4HD and UMIK-1 would probably be your best bet. The MiniDSP has a ton of delay you can add if necessary. Have you tried corner loading that rear subwoofer? Changing placement should be the first step, then you fine tune with DSP
 

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Discussion Starter · #14 ·
I agree. It's Marantz SR7013. All three subs are XTZ 10.17 Edge with PEQ. Internal delay is an issue. Even with PEQ off.
The rectangular proportions of the room will make a difference as to whether 1/3 and 2/3 or 1/4 and 3/4 placement on the front wall work best.
Can you elaborate om this? How can this be estimated? REW simulator is far from accurate in my room. Could be that it extents to another room? It's All one room more or less.
 

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Discussion Starter · #15 ·
Time aligning and gain matching with something like a MiniDSP 2x4HD and UMIK-1 would probably be your best bet. The MiniDSP has a ton of delay you can add if necessary. Have you tried corner loading that rear subwoofer? Changing placement should be the first step, then you fine tune with DSP
Corner loading the rear sub kills the low extension for some reason. I can fix this, but overall response is worse than the current setup.
 

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Can you elaborate om this? How can this be estimated? REW simulator is far from accurate in my room. Could be that it extents to another room? It's All one room more or less.
Perhaps, I really don't know. Rooms are pecululiar things when it comes to LF bounce and reflections. I have a slightly larger but similar shapeed room with a larger opening at the rear. Strangly and similarly as you describe, I got my best (and it's really good) LF EQ with two larger subs on the front stage rather than any other combination...and I exhausted every possiblity. I really recommend getting your MLP closer to 1/3 room length from the front stage and perhaps trying just two larger subs that can pressurize the room better than 2 10" subs.
 

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Lenght: 6.80 meters
That's not really the length of your room, since half the back wall is missing and open to a larger space. This can make it difficult to know whether the 80Hz null is due to a length mode, especially since your main listening position is exactly where your room is transitioning between lengths.
Front subs 95 cm from side wall (1/4)
That's a good starting point because centering your subs at the 1/4 and 3/4 points of room width can cancel the first 3 width modes (45Hz, 89Hz, 134Hz) and all the peaks & nulls caused by those modes. This only works if both subs have identical delay and gain (feed both subs from the same output on your receiver).
Back sub 170 cm from right wall.
If the back sub is on a separate output, try adjusting the delay to see if it changes the severity of the 80Hz null.
 

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Hi everyone,

I have 3 10" subwoofers. 2 front and 1 behind MLP.

I get a Deep null at 80hz in stereo mode in REW. I can fix this by adjusting subwoofer distance or variable phase. But that induces more problems. I can't increase subwoofer distance due to limitations in Audessey as they are already at max.

Fronts only show a mild dip. Subwoofers only stable linear curve from 20 - 120hz. Crossover at 110hz fix everything with the default Audessey distance settings.

What to do? Buy a minidsp, crossover 110hz? Tried to even things out in Multeq without success.

MLP is almost in middle of the room. Can't change this. View attachment 3121458

Thanks.

Hi,

A miniDSP will certainly help, but there are a couple of other things I would also try. Since your front subs are in a cabinet, I can understand that you would be reluctant to move them, even if they didn't already give you the best response where they are. So, let's skip the idea of moving the front subs.

I agree with others that sitting close to the exact center of a square or rectangular space is swimming upstream with respect to bass frequencies. I understand why you can't move the seating area forward, but you might be able to move your L-shaped couch backward by a foot or two without any real harm. I think that you would get used to a little different viewing distance from your screen pretty quickly. You can measure a foot or two behind your current main listening position, just to get an idea of whether moving the couch backward a little would help.

The other thing I might try is to position the rear subwoofer directly behind your MLP. A very nearfield sub is less susceptible to room modes, so it's possible that you will get decent results just from getting it very close to your MLP. You might like some other things that does for you too. With the distances that your three 10" subs are located from your MLP, you are making them work pretty hard even at nominal volume levels.

My final thought concerns the 80Hz null itself. Nulls are deep by definition. The real key though is how wide they are. A narrow null, however deep, may not create an audible difference from a completely flat response. That is because, at those frequencies, each note in an 8-note octave covers several frequencies. (An octave is any doubling in frequency.) Our brains are pretty good at filling-in for missing information as long as the area of cancellation isn't too wide.

Where I am going with this is that people sometimes spend a lot of time chasing an area of cancellation, without knowing whether it actually makes an audible difference or not. That might be something you would want to check-out. There wouldn't be cancellation at that frequency at some other spots in the room, so you could compare the sound to determine just how important that 80Hz null actually is.

Regards,
Mike
 

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Hi everyone,



I get a Deep null at 80hz in stereo mode in REW. I can fix this by adjusting subwoofer distance or variable phase. But that induces more problems. I can't increase subwoofer distance due to limitations in Audessey as they are already at max.
The online manual I found for your receiver says max sub distance is 18 meters/60 ft. Is that the setting? Even allowing for some amp induced delay that seems off.
 
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