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Discussion Starter · #1 ·
Hello,

I have the Jamo D600 THX Ultra 2 speakers 5.2 setup with a set of Jamo D600 subwoofers. I have placed the subwoofers between the left centre and right centre speakers up front as suggested by Jamo. The subwoofers are in a cabinet up front which is just a wood frame structure as the top and front structure are covered with perforated cloth. The subwoofers are sitting on a 1.5inch non porous foam to cut resonance and unwanted vibrations.

My problem is that i have read endless topics that 4 subwoofers is the ideal number to have better sound balance and distribution in the room. Well i have got a very good deal and bought 2 Jamo D660 subwoofers which are 12" instead of the 15" of the D600. My room is quite small at 16ft x 11ft with a 10 ft ceiling. When i try to put the 4 subwoofers in my room, i can never get a good sound when i put the small subs at the back of the room its like they are not working and the best sound i found is when i put all the subwoofers at the front, so basically the small 12" in each corners with the D600 close to each one of them between the centre speaker.

Is this a wrong method to have 4 subwoofers up front? I tried endless possibilities. One sub on each wall symetric, one on each wall assimetric, One sub in every corner you name it, i tried it. My room is treated with absorbers and reflectors to my best knowledge but whatever i do when i put the subs at the back of the room it seems that the subs are not working. Up front you can instantly feel that the small subs really help the big subs. I calibrated the big boys to handle frequencies at around 100hz and lower, and the small subs are just helping from 50Hz down. I also tried running just the D600 15" subs alone and to my surprise these sound better then when i run 4 subwoofers with 2 up front and 2 at the back. Is this really possilbe? If anyone has ever heard of a setup including 4 subwoofers up front i would like to hear some suggestions in this regard. Thank you for your time into reading my long explanation.
 

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"up front" says it all. You cannot pre-define the position of the subs based upon aesthetics and expect to get the best output in your room. Be open to other positioning options and you will reap the sonic benefits.
 

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When you put the 2 subs in the back of the room, did you adjust their phase?

If not, there's your problem right there. ;) If the subs aren't in-phase they will cancel each other out.

While playing the sub test tone from your AVR (with all 4 subs playing), adjust the phase on the rear subs for highest SPL at the Main Listening Position (MLP). You will most likely end up with a setting of "180" on the rear subs (depending on how close they are to the MLP). If you don't have an SPL meter, an SPL meter app on a smartphone will work in this situation.
 

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Discussion Starter · #6 ·
When you put the 2 subs in the back of the room, did you adjust their phase?

If not, there's your problem right there. ;) If the subs aren't in-phase they will cancel each other out.

While playing the sub test tone from your AVR (with all 4 subs playing), adjust the phase on the rear subs for highest SPL at the Main Listening Position (MLP). You will most likely end up with a setting of "180" on the rear subs (depending on how close they are to the MLP). If you don't have an SPL meter, an SPL meter app on a smartphone will work in this situation.
That is a good suggestion that i will try as right now i am moving my subwoofers all the time around the room and trying Phase will not really be a major issue. In all the reading about multiple subwoofer installations i saw they all suggested one sub midpoint on each wall, which i can easily do and the door entry is on the side, so for me corner placement of all the subs is not possible.

What i have is like a line array with 4 subwoofers up front, but it seems that it is never suggested for home cinema applications. Yesterday i switched off the small 12" subs and calibrated my dual 15" up front and i got very good results, but since everywhere i read the suggestion is to put 4 subwoofers since i have them i might play around and get a better result. Thank you for the suggestions, shall keep you posted.
 
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