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
Hello handymann,

     Well, it seems like we now have a few contenders for high quality methods for integrating subs into one’s system; the distributed bass array, the line bass array and now, the DBX Venue 360 device. Since the DBX Venue 360 is basically an equalizer and room correction device, however, my main concern is that very high powered amps would also be required for it to operate effectively.
     I have little doubt this unit is able to correct all the frequency peaks it identifies in a room, since it merely needs to direct the amps to reduce power at the appropriate frequencies or filter out the excess energy.  But I do doubt this unit, without considerable amp power used in conjunction, is able to correct all the frequency dips it identifies in a room, since it needs to direct the amps to increase power at the appropriate frequencies. Correcting frequency response dips requires significant amp power, possibly even a doubling or more of power at bass frequencies.
So, the DBX Venue 360 could be performing its function perfectly but there’s insufficient amp power to correct all the room’s frequency dips it has identified.
     Handymann, how many amps and how much amp power do you utilize for your subs and main speakers? Do you have a sense of whether or not your system amp power is sufficient to correct all the frequency dips in your room identified by the DBX without straining these amps?

Thanks,
Tim
@noble 100:
Ii have two Krell EV-600 monoblocks and two JL Fathom 13’s.  I have not had to increase the subs volume, or turn up my preamps volume since utilizing the dbx unit.  It has a max output of +22 dBu through balanced outputs.  You can also delay the subs or main speakers output, to properly align the subs and main speakers, as well as adjust phase of both on the fly.
@rooze 

I have a REL S5 and the sense of space that it creates with my PSB T3's in my listening area is amazing. Both on music and home theater. The REL mission statement is all about doing exactly what you want. The S5 was just replaced in the REL lineup 2 months ago by the S812.

GLHF!
I certainly do not claim to be an expert, but I can add this; Take a sub driver and main woofer out and measure the distance  from the mounting surface to the center of the magnet, and not at an angle from one to the other.  Make certain the sub cabinets and mains cabinets are positioned from the front to of the cabinet,  exactly the distance as the difference between the two measurements. Allow for the thicknesses of the two cabinets, if necessary.   This will phase align all your woofs. It really works. 

We humans may not hear directionality from the woofage, but the laws of physics are not waived because of that fact.   
danvignau,

    I know you're referring to phase alignment of the woofers.  But I just wanted to add a bit of information to readers about concerns with a somewhat related topic: aligning arrival times of midrange /treble soundwaves with bass soundwaves at our ears. Briefly stated: don't even bother to be concerned with it.  
    Midrange/treble complete cycle soundwaves are very directional and short compared to bass complete cycle soundwaves that are omnidirectional and very long.  A 20 Hz deep bass soundwave is 56 feet long and a 20,000 Hz high treble soundwave is a fraction of an inch long.  Because of this, midrange/treble soundwaves behave very differently than bass soundwaves do in any given room.  
    With the main speakers pointed directly at your listening seat, the short and highly directional midrange/treble soundwaves are going to take a direct path and reach our ears first and fairly quickly, before the omnidirectional bass soundwaves that take an indirect path and typically bounce off multiple room boundaries (floors, walls and ceiling) on their way, before arriving at our ears  a bit subsequently.  One would think this results in the bass being perceived as somewhat lagging behind but it does not; the arrival times of the bass, midrange and treble are perceived as properly time aligned.  
     There's an explanation for this that I believe is important to understand but I don't recall what the explanation is.  Can anyone explain why the arrival times of bass soundwaves slightly after midrange and treble soundwaves at our ears doesn't appear to be important?

Thanks,
  Tim