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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
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).
kenjit
1,771 posts
 
 I also make my own loudspeakers 
which if i recall correctly has been heavily ridiculed by the experts on diyaudio. 
enginedr1960
173 posts
 
I use a distributed bass system in my room . My subwoofer use stared with one sub and then two in stereo with a DSPeaker Antimode 2.0 DSP device . The sound at the listening position was good but not even across the room . After adding two more subs this improved . In the past three weeks I added two more and did another room correction . The sound in the room at all frequencies improved . This leads me to wonder if a bass mode in a area not in the listening position affects the sound as a whole ?  
audiokinesis
2,724 posts
 
@rooze asked, "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?"

Briefly, a distributed multi-sub setup is quite flexible in positioning and phase. I have yet to have a customer fail to achieve a good integration with his mains. The relative uniformity of the low frequency sound field with a good distributed multisub system means that you aren’t "rolling the dice" when it comes to blending with your mains. 

The minor differences in arrival time at the listening position are a much smaller fraction of a wavelength than what the ear can resolve at low frequencies. How uniformly the low frequencies decay in-room is of greater audible consequence. Speakers + room = a minimum phase system at low frequencies, which means the time-domain response tracks the frequency response. Fix one and you have fixed the other.
@kenjit wrote: "There is no such thing as swarm."

A the risk of stating the obvious, the guy who manufacturers the Swarm begs to differ.

Duke
yes, I’m that guy
rooze's avatar
rooze OP
580 posts
 
@gdnrbob
Thanks for your input. I’ve been tempted by the Vandy approach a few times over the years but I’ve never pulled the trigger on a pair. I think I’ve been put off a little by the need for placing an extra crossover in line. At least that’s how I remember them working. I’ll take a refresher on the Vandersteens tomorrow when I’m more awake!
Cheers
Rooze 
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