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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
erik_squires
15,874 posts
 
EQ is a lame idea, DSP or otherwise. But no more lame than taking advice from a bunch of guys with absolutely zero idea what they’re talking about. Which is every single post so far!



Hello @millercarbon,

We have gotten to the unfortunate part of a discussion where you assert knowledge of your own little in evidence and denigrate that of others leaving me no choice but to out you.

I used to work in motion picture equipment industry, including design, installation and set up of some of the best sounding motion picture audio gear in the world. I also make my own loudspeakers and do my own room EQ.

My views are pretty much the same as those posted by JL Audio, though as I posted elsewhere, I disagree with them in some nuanced ways:

https://forum.audiogon.com/discussions/me-vs-jl-audio-an-open-discussion?highlight=me%2Bvs%2Bjl%2Bau...

The problem you’re having rooze, and the mistake you’re making, is the same one I made and everyone makes and that’s following the conventional wisdom, because the conventional wisdom is WRONG! The conventional wisdom is based on the idea that because sound is waves and bass is waves then bass must be the same as midrange and treble. When its not.

That’s not the conventional wisdom, and not what I’ve seen anyone propose. The general solution, as written by and accepted by professional acousticians and installers, for getting deep bass in a room with moderate spend is bass traps + EQ.


http://ethanwiner.com/basstrap_myths.htm


My views and recommendations are also largely in line with what GIK Acoustics would recommend, so please, contact them directly and ask.

https://www.gikacoustics.com/

If you have lots of room, time and money, get more subs, and a custom room. Otherwise, I stand by my advice of using a DSP based solution along with appropriate room treatment and question your judgement and qualifications.

Best,

Erik
millercarbon's avatar
millercarbon
12,531 posts
 
Sorry. Remind me again, about your experience setting up and using your distributed bass array?
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 ?  
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