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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

Showing 2 responses by audiozenology

audiozenology
362 posts
 
I am not familiar with the JL subs room correction so I can't comment on what it will do or not do, but some general thoughts:

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’.


This suggests to me that your subs perhaps are crossed over too high?   How big is your room out of interest?

If I am not mistaken, the SC-3 dips pretty low (40Hz -db quick check?). Probably want to cross over at about 50Hz for music (+/- 5 hz), and get the volume matching right (and phase).  50Hz is about 7 meters, so 180 degrees phase is 3.5 meters (needed when making a bass array - or inverted audio inputs/outputs/speakers).

At that frequency, you should not have localization impacting sound-stage perception. Not sure how steep your sub cut-off is. They are usually fairly steep, so higher frequencies above the cross-over should not be an issue.

In terms of a bass-array, yes they are great. They are even greater when you invest $100 in a microphone to let your tune the bass-array across your listening position. If you have phase adjust (not just 0/180) you can do some virtual movement  (and digital delay can do more).
audiozenology
362 posts
 
Ideally the sub should be crossing over from the mains at a frequency where localization isn’t possible rendering time alignment not critical. If you force time alignment, then you force maximum wave reinforcement in the listening position which negates the point of a distributed bass array to even out frequency response by negating room modes.


Ideally the sound from the sub should reach the listening position at exactly the same time and at exactly the same phase angle as the woofers in the satellite speakers.

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