# Individual Sub adjustments on Dual Sub setup?



## tratliff (May 25, 2010)

If I understand correctly, the goal is to adjust both subs together to make the best FR as a pair and to also make the transition between subs and mains the smoothest.

*But*, _prior to that_, are there certain steps I need to take to each sub _individually_ to ensure that the combined sub output is the best it can be? 

Do I need to level match each sub?

Do I need to experiment with different polarity or phase on either sub?


Both subs are located behind and about he same distance from the MLP. The room and WAF do not allow movement in position of the subs.


Equipment:
JL Audio Fathom subs (2)
Marantz AV8801 pre/pro with Audyssey XT32
REW
UMIK-1 with HDMI
Triad in-wall speakers (7)


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## jtalden (Mar 12, 2009)

You have selected the SW, mains and LP locations so you are all set. There is nothing else to adjust if you are intending to use Audyssey. It will take care of distances and levels as well as EQ.


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## willis7469 (Jan 31, 2014)

tratliff said:


> If I understand correctly, the goal is to adjust both subs together to make the best FR as a pair and to also make the transition between subs and mains the smoothest. But, prior to that, are there certain steps I need to take to each sub individually to ensure that the combined sub output is the best it can be? Do I need to level match each sub? Do I need to experiment with different polarity or phase on either sub? Both subs are located behind and about he same distance from the MLP. The room and WAF do not allow movement in position of the subs. Equipment: JL Audio Fathom subs (2) Marantz AV8801 pre/pro with Audyssey XT32 REW UMIK-1 with HDMI Triad in-wall speakers (7)


Yes you need to set the level of each sub, then together with the LFE gain in the AVR. Turn on one sub and run the test tone, so it's about 72db. Turn off that sub, and turn in the other one. Set it for 72db also. Now turn on the first one also and measure together. This is where you'll want to move the phase controls to find the most output. This a good start. Then I'd run audyssey, and then rew. I understand much of your placement/WAFwoes. (See pic). What does audyssey set your crossover at for mains?


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## willis7469 (Jan 31, 2014)

willis7469 said:


> Yes you need to set the level of each sub, then together with the LFE gain in the AVR. Turn on one sub and run the test tone, so it's about 72db. Turn off that sub, and turn in the other one. Set it for 72db also. Now turn on the first one also and measure together. This is where you'll want to move the phase controls to find the most output. This a good start. Then I'd run audyssey, and then rew. I understand much of your placement/WAFwoes. (See pic). What does audyssey set your crossover at for mains?


...sorry just realized your using xt32. If you've run 2 separate cables, your prob good. Except phase.


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## tratliff (May 25, 2010)

Thank you both so much for the advice.


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## willis7469 (Jan 31, 2014)

You're quite welcome. Sorry for the windy first reply. In so used to doing that way, and I realized after all that, you were using xt32. Nice equipment list. You like your JL's? (Dumb question I know). I just like hearing others impressions. 
Will


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## tratliff (May 25, 2010)

Honestly Willis, the JL subs don't have the impact I was wanting. I got the first one and was underwhelmed. So I got another and it helped but still is lacking in my opinion.

But the problem is the room I believe, not the subs. I have a large great room with high ceilings that is open to a hallway, dining room, and breakfast area. The open floorplan makes it difficult for all the speakers (subs and mains) to give me what I think is a good sound. _Maybe_ I can move one sub to the front of the room and see if that helps.

I'll post some graphs in another thread next week and let you and others see what the sound looks like and if there is anything I can do to help the situation.


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## jtalden (Mar 12, 2009)

I suspect you are correct:
A lot of rooms have a sag in the mid bass area (100-180Hz) due to room modes. A sag in this area takes the weight out of music. Two JL Audio Fathom subs have lots of capacity for all typical sized rooms. If they are crossed at 80 Hz they have no impact in this mid bass range and thus have no direct effect. Increasing their level does not really resolve this issue. Although, I suspect this is related to why we see so many house curves with a +5-10dB SW boost. It is the result of trying to compensate for this problem. I also suspect that the results are not very satisfactory. 

If the REW measurements of each channel shows this range to be a little soft, that range may be the real issue that needs to be addressed.


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## willis7469 (Jan 31, 2014)

tratliff said:


> Honestly Willis, the JL subs don't have the impact I was wanting. I got the first one and was underwhelmed. So I got another and it helped but still is lacking in my opinion. But the problem is the room I believe, not the subs. I have a large great room with high ceilings that is open to a hallway, dining room, and breakfast area. The open floorplan makes it difficult for all the speakers (subs and mains) to give me what I think is a good sound. Maybe I can move one sub to the front of the room and see if that helps. I'll post some graphs in another thread next week and let you and others see what the sound looks like and if there is anything I can do to help the situation.


Agreed. It is most definitely the room, and probably just too much for sealed subs, especially in extension. I also have a cavernous space to fill, and while i mostly can't pressurize it like a closed space, it will to a point. The only sealed subs I would consider for that job would be Gothams, or triax.(over budget) The biggest contribution to overall performance in my space was getting the phase right. Near field placement helped too. I did try opposing corners (both ways) but it didn't do what I hoped. It may for you though. Every room is different. Looking forward to your graphs. 
Will


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## tratliff (May 25, 2010)

Here are my measurements of my subs only. What a mess !!
The first graph is of the left sub, right sub, and both subs.

I posed the question of what I needed to do to each individual sub to get the best combined response. So I did many measurements testing for the response differences in varying polarity and phase adjustments. What I found was that polarity changes had a very negative impact but phase adjustments may be beneficial. 

The second graph is the result of these test and shows the four best responses. What do you think?

Will Audyssey XT32 help this mess?

Which of the phase settings (see second chart) should I use prior to running Audyssey? Or should I leave both subs at 0 phase?

Should I get a miniDSP to fix some issues?

Is there any hope for decent low-end?


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## willis7469 (Jan 31, 2014)

tratliff said:


> Here are my measurements of my subs only. What a mess !! The first graph is of the left sub, right sub, and both subs. I posed the question of what I needed to do to each individual sub to get the best combined response. So I did many measurements testing for the response differences in varying polarity and phase adjustments. What I found was that polarity changes had a very negative impact but phase adjustments may be beneficial. The second graph is the result of these test and shows the four best responses. What do you think? Will Audyssey XT32 help this mess? Which of the phase settings (see second chart) should I use prior to running Audyssey? Or should I leave both subs at 0 phase? Should I get a miniDSP to fix some issues? Is there any hope for decent low-end?


Well to start, yes there is hope! I had to spend a little time revisiting your thread. Could you elaborate on dimensions and layout a little more. Also, measurements of the subs in relation to the walls and LP. I found that even one foot can make a difference. 
When you say polarity and phase, in my mind that's the same. Not sure what you mean here. One good thing here is because you're using in wall, placement issues for those are zero!
Also you mentioned putting one sub in front. Have you tried that yet? Or stacking? From your graphs, I don't see anything unmanageable. Especially with XT32. I'm trying to multitask at our family store today, so I apologize if my questions seem perforated.


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## tratliff (May 25, 2010)

This is a Great Room/Living Room with dimensions of the room are: Depth 20 ft, Width 28 feet, Heigh 12 feet. BUT, the left side is open to a hallway and dining room to the rear, and the back is partially open to the breakfast area. The open floor plan is not good for sound I don't think. All speakers except the subs are in-wall. The subs are located on the rear wall about 5 feet being the MLP. One sub being directly being the MLP and one 5 feet to the side. Unfortunately décor dictates the location of the subs also and even 1 foot is not an option.

Glad to hear it's not hopeless! It just seems to be a much uglier graph than all of the others I see here.

This afternoon I am going to run Audyssey XT32. I guess I'll leave the phase at zero on both subs for now, even though setting the right sub at phase of 90 did show a better (flatter) measurements. I'll post the results later. Thanks.


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## tratliff (May 25, 2010)

Well I tried running Audyssey but looks like there is an issue with the mic. It isn't picking up the full-range sounds. I'll have to get this fixed then run it at a later date.


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