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Subwoofers and Phase Question For You Sub Experts

I use a pair of Dunlavy SC-3 speakers, known for their time/phase coherent crossover design.

When the stars align the speakers completely disappear and there’s a sense of space and 3 dimensionality that I’ve heard from few other speakers/systems. It’s easy to destroy the illusion with things like poor placement, poor setup of room treatments, etc.

Adding subs to the setup is both a blessing and a curse. The Dunlavy’s need some support in the nether regions and a pair of HSU subs do add a solid foundation to music which enhances the overall presentation; however, it’s at the expense of some stage depth, width and image dimensionality. Placing the subs a few inches forward of the front plane of the speakers helps a little but that isn’t where they perform at their best as ‘subwoofers’.
Finding optimal room positions for bass augmentation always creates a clash with the phase aspect of integration resulting in the diminished soundstage described above.
Playing with phase settings has little impact on the problem since there’s just a toggle for 0 and 180.

Which brings me to the questions - 
1/ How does running a swarm setup, with 4 subs, affect phase/time integration with the mains? Does it create twice or half the issue or remove it altogether?

2/ Looking at subs such as the JL Audio F series with auto room calibration, does the EQ algorithm compensate for any time/phase anomaly or is it simply looking for a more linear bass response?

I don’t mind investing in more sophisticated subs so long as I don’t end up with the same problem. I’m not really inclined to mess with software and the like, unless there’s no other way.

Thanks

Rooze


128x128rooze
danvignau's avatar
danvignau
935 posts
 
I certainly do not claim to be an expert, but I can add this; Take a sub driver and main woofer out and measure the distance  from the mounting surface to the center of the magnet, and not at an angle from one to the other.  Make certain the sub cabinets and mains cabinets are positioned from the front to of the cabinet,  exactly the distance as the difference between the two measurements. Allow for the thicknesses of the two cabinets, if necessary.   This will phase align all your woofs. It really works. 

We humans may not hear directionality from the woofage, but the laws of physics are not waived because of that fact.   
noble100's avatar
noble100
2,419 posts
 
danvignau,

    I know you're referring to phase alignment of the woofers.  But I just wanted to add a bit of information to readers about concerns with a somewhat related topic: aligning arrival times of midrange /treble soundwaves with bass soundwaves at our ears. Briefly stated: don't even bother to be concerned with it.  
    Midrange/treble complete cycle soundwaves are very directional and short compared to bass complete cycle soundwaves that are omnidirectional and very long.  A 20 Hz deep bass soundwave is 56 feet long and a 20,000 Hz high treble soundwave is a fraction of an inch long.  Because of this, midrange/treble soundwaves behave very differently than bass soundwaves do in any given room.  
    With the main speakers pointed directly at your listening seat, the short and highly directional midrange/treble soundwaves are going to take a direct path and reach our ears first and fairly quickly, before the omnidirectional bass soundwaves that take an indirect path and typically bounce off multiple room boundaries (floors, walls and ceiling) on their way, before arriving at our ears  a bit subsequently.  One would think this results in the bass being perceived as somewhat lagging behind but it does not; the arrival times of the bass, midrange and treble are perceived as properly time aligned.  
     There's an explanation for this that I believe is important to understand but I don't recall what the explanation is.  Can anyone explain why the arrival times of bass soundwaves slightly after midrange and treble soundwaves at our ears doesn't appear to be important?

Thanks,
  Tim
millercarbon's avatar
millercarbon
12,531 posts
 
I just wanted to add a bit of information to readers about concerns with a somewhat related topic: aligning arrival times of midrange /treble soundwaves with bass soundwaves at our ears. Briefly stated: don't even bother to be concerned with it.  
    Midrange/treble complete cycle soundwaves are very directional and short compared to bass complete cycle soundwaves that are omnidirectional and very long.


Exactly. Two completely different animals. This may be one of the hardest parts of the whole thing to understand. Though granted, the whole DBA approach relies on a number of hard to understand concepts. No one of them really so much hard as different. At least I feel it must be something like that. Else why so many have explained so clearly and yet so few seem to get it?

This one though I give top honors because if there's one thing we all know for sure its that timing matters a lot. With full range speakers everything must be done just right or you will get poor if any imaging, and it will be obvious where the sound is coming from. With subs, and especially with a swarm, you can plop them down just about anywhere and never know. The first few weeks with mine I lost count how many times I walked right up to one and finally wound up putting my hand on it just to be sure it was working.

But then this should be obvious, if for no other reason than a lot of us run these things pointed at the wall. Hello! At. The. Wall.

How much more different you can get than that, I just don't know.
tomic601's avatar
tomic601
13,078 posts
 
First for the OP - great choice of main speakers, wish he was still alive along with Jim T
( yes I owned and sold both ) and have Vandersteen to this day , time and phase do matter and most importantly above 120 HZ) the Vandersteen sub 9 is a swarm with analog 11 band EQ for each of the 4 subs to fix room issues below 120 and w aysemetic cut vs boost. 
Swarm fixes freq response issues caused by room, analog EQ fixes bass at listening position

dsp probably screws up time and phase above 120

have fun, Tori Amos beackons....
tomic601's avatar
tomic601
13,078 posts
 
Also for students of the bass, yes I am a hack but I can get around a fretless, the wave is BIG, bigger than most rooms....so reality is the wave is folded and truncated anyway, which IF ya think about it absolutely F the phase...

IF you like math, get Olsons excellent and of course still very relevant text: Elements of Acoustical Engineering

but you also need a reference for accurate bass, two that I use are Ray Brown - Soular Energy and JD Souther - Silver Blue off of Black Rose ( Stanley Clarke, man that cat can play )

both of these recordings will reveal image shift at between 80-150 HZ 

you can figure out the notes ;-)
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