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
I concur, I lived the one sub then two subs scenario and yes I had deep bass from two big subs but did not sound like natural bass. Shopping for speakers I met Duke and got his speakers, I have to say the sub array was an extra on the purchase as I wasn't looking for subs I had doubts honestly the Dayton sub amps (because of the price) will integrate and control the subs properly, I looked into more complex sub integration like mini dsp, dspeaker, trinnov etc but with digital dsp comes a side effect within the digital world which is losses during conversion if you are using hires content, anyway the subs arrived, I installed the them and was very surprised how well Duke's approach worked, I sold my two big subs and never looked back. The sub array takes almost no space as a matter of fact less space than my previous 2 subs and I have 4 now, can be easily positioned anywhere and the sound is natural bass not boomy, the daytons will provide all the phase controls and analog corrections needed, the price for the entire 4 sub system is the same or maybe a little less than the 2 subs.

Keeping this on thread for the OP the 4 sub approach allows you to put the subs almost anywhere and makes the positioning simpler and more inline with the geometry, because of the reasons already explained above by Duke himself, some others here are using 6. The daytons allows you to change the phase gradually not only 0 and 180 that is something digital sub integration usually don't have and I think not because is hard to do but the manufacturers haven't seen a need for it, I say usually because the high end ones trinnov comes to mind have it but be ready to hurt your wallet.



@bdp24 your statement makes sense, I don't completely understand the acoustics behind it, I understand physics and kind of grasp the concept but not entirely. Now the empirical evidence and testing of before and after proves me this solution is perfect, affordable and more importantly something people don't mention scalable, should you move to another bigger house or listening room just add 2 more little subs.




The other things I love about the Vandersteen approach to subs is the way he his amps/x overs mimic the sound of the main amp.  If you spend money on a very expensive amp, his sub amps (AB type) mimic the sound so you don't have that fight either.  It does make a difference to my ears.  

I personally don't like any of the DSP I've heard as it takes away from the sound.  Some are bette than others, but even at the stores that sell DSP, most agree, but it's so easy to set up and most don't listen for the differences as they want it to sound better than analog EQ. ;) 
Auto EQ is soooo variable.  

It is damn convenient and anyone can ise them, but I can understand why many dislike the results.  So, Dirac and JL have good results.

I love my miniDSP but what a PITA to set up right

gosta:"Tried the "swarm" approach and moved four subs into the room but unfortunately found out that they all have about the same tops and dips wherever placed (+/- 20 db from 25 to 100 Hz). So not much of an improvement. Room eq necessary."

Hello gosta,

     As Duke mentioned, something is likely wrong in your positioning of the subs or configuration if you didn’t notice a dramatic bass improvement using a 4-sub DBA in your room. I suggest you may want to answer Duke’s questions to you on his reply if you’d like to figure things out, he knows more about attaining good bass than anybody I’m aware of.
     In the meantime, I thought I’d share how I setup my 4 subs just in case it might work well for you. I have the Audio Kinesis Debra 4-sub DBA system using a single sub amp/control unit. However, I don’t know which 4 subs you’re using, a complete AK Swarm or Debra bass system kit or 4 traditional self-amplified subs. Either should work well, it’s just that you’ll need to adjust the volume, crossover frequency and phase controls on each sub individually if you use traditional self-amplified subs. On the Swarm and Debra, you just need to adjust these controls once on the included amp/control unit for all 4 subs as a group.
     But either way, following my positioning method could be helpful to you:

1. Disconnect your main speakers and move them to another room.
2. Hookup sub#1 and place it at your listening position. If you’re using self-amplified subs, do the same thing but set the volume to 50%, the crossover frequency to 40 and the phase control to "0" (in-phase).
3. Play some music with good and repetitive bass.
4. Starting at the front right corner of your room, slowly begin walking in a counter-clockwise direction around the perimeter of your room listening for the first exact spot that the bass sounds best to you (solid, detailed, dynamic and natural). Take your time, listen carefully and repeat this step until you are certain you’ve found the exact spot.
5. Once you’ve identified the exact spot, move sub#1 from your listening position to this exact spot.
6. Hookup sub#2 and place it at your listening position. If you’re using self-amplified subs, do the same thing but set the volume to 50%, the crossover frequency to 40 and the phase control to "0" (in-phase).
7. Play some music with good and repetitive bass.
8. Starting at sub#1, slowly begin walking in a counter-clockwise direction around the perimeter of your room listening for the next exact spot that the bass sounds best to you (solid, detailed, dynamic and natural). Take your time, listen carefully and repeat this step until you are certain you’ve found the exact spot.

9. Once you’ve identified the exact spot, move sub#2 from your listening position to this exact spot.
10. Repeat this procedure for subs #3 and #4, beginning from sub#2 for placing sub#3 and from sub#3 for placing sub#4.
11. Bring your main speakers back into the room, hook them up and position them optimally in relation to your listening position for midrange/treble and imaging. You now have 2 systems: an independent powerful,fast, smooth,detailed and dynamic bass system as a solid foundation and an independent everything else system consisting of any main speakers you choose to use.

     Once all 4 subs have been positioned, the final step is to optimally set the volume, crossover frequency and phase controls. It’s much easier to do this if you sit at your listening seat and have an assistant adjust the settings at your direction. I achieved the best results by precisely setting the volume and crossover frequency as low as possible with the bass still sounding powerful, fast, smooth, detailed, dynamic and natural. I set the phase at the position at which the bass subjectively sounded the best to me.

     As I mentioned earlier, these 3 settings are set once, for all 4 subs as a group, on the Swarm/Debra amp/control unit but must be individually for each sub if traditional self-amplified subs are utilized.


Hope this helps,
Tim