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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


rooze

Showing 2 responses by audiorusty

audiorusty
305 posts
 
I have been a fan of subs before having subs was cool.

I have a hybrid of what others have already mentioned.

I started out with one sub. That did not work out so well. I liked the big low end but the mid bass was muddy. Lots of phase/time  issues going on. I pulled the single sub out and replaced it with two sealed subs and an active crossover. I played with the phase relationship between the two subs and delayed the signal to the mains. This worked pretty well. I had nice solid low end, great impact and much more detailed mid bass and when I sat in the listening position I felt like I was wrapped up in the sound, but it wasn't perfect. If I stood up or moved a few feet the low end changed, usually becoming a bit boomy.

I have been intrigued by the DBA system for quite some time but wasn't sure how to implement it in my room. My room is very small at 14x10x9 with a couple of doors and a big honkin radiator in less than ideal locations, not to mention I wanted to hear one before I buy. A couple of weeks ago I had the DUH moment. I still have the original sub the that I pulled out of my system to sell but hadn't, so I stuck it behind the couch, hooked it up and I had better bass all through the room including the listening position.

All of my subs fire into the room. The front two subs fire towards the listening position and the sub behind the couch fires 90 degrees to the front subs. I did not spend any time trying to optimize the location or did any phase adjusting of the third sub. I just plopped it down, hooked it up and turned it on. I did and still do, play with the volume level.

I am not a reviewer so I may have more tools that I can use but I do believe that a DBA system has merit and can be easier to integrate than a single or two sub system can be. 
audiorusty
305 posts
 
Playing with phase settings has little impact on the problem since there’s just a toggle for 0 and 180
This is not phase. This is polarity.
Some of the more upmarket subs have 360 degree control
This is phase. This basically helps to achieve maximum output level of the subs.
but the subs are obviously affected in the same way as the mains by the room modes and the frequency response anomalies.
 Multiple subs helps with this issue.
There's almost a smearing affect where the air and space around images diminishes and that's what I'm referring to as a 'phase anomaly'.
 This could be caused by an overlap in frequencies being produced by your mains and your subs. This is an issue that a crossover or speaker management system can eliminate. If you do not want to do an external crossover set the low pass filter on your subs to the low end cutoff point of your mains. Plugging any ports should also help.


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