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Hello all,
I am planning to set up my 1.6QRs with dual JL Dominion D108 subs. At least initially, I am planning to set the subs against the wall behind the 1.6 and a little closer together than the speakers.
In other words, you would be able to see the subs set closer together at the far wall behind the speakers.
But that gave me a thought.
How would the fact that the rear wave of the speaker is 180 degrees out of phase affect the phase setting of the subwoofer, which would be pushing sound in phase with the front of the panel, but colliding with the out-of-phase sound emanating from the rear?
Has anyone set up their subs in a like manner and found they ended up with the sub's phase set at 180 degrees?
Follow Ups:
impossible to do it right without REW and a microphone.
It's important to work on integrating any subwoofer with any system.
There are several aspects to this. Phase over the crossover region is important - remember that a crossover is not a brick wall where the subwoofer stops and the main speaker immediately starts - even the 48 dB per octave slope (or higher) possible with DSP crossovers, there is still some overlap and in that region phase will have an impact on the sound in the room. I have found it useful to take measurements at my listening position when adjusting phase of the subwoofers in my system. One can easily see something of a null ( suckout ) when the phase is dead wrong, but you may see too much of a peak if the phase is correct. Eq can help here, especially as the crossover region tends to be coincident with main room modes in most domestic listening rooms. If you fiddle with it enough, you CAN get it right, at least in terms of a smooth amplitude transition between subwoofer and panel speaker.
Keep in mind the wavelengths we are dealing with here - the wavelength of a 60 Hz sound wave is almost 19 feet. Moving the subwoofer a few inches isn't likely to have much impact.
The other characteristic which I find it is important to try and match between subwoofer and woofer panel is "bass overhang" sometimes also referred to as "bass speed" - A subwoofer pressurizing the air in a box is going to cause that box structure to store some of the energy pumped in by the cone motion. No matter how rigidly built or perfectly damped, that box is going to radiate that stored energy in the room over time, on a time scale that is longer than the actual bass note or impulse. Panel speakers don't have very much stored energy, and so matching a panel speaker with a box subwoofer just does not sound quite right to me. I had some box type subs, and yes they filled in the lowest octave and prevent trying to drive the panels with all that bass power, but it didn't sound quite "matched." It sounded "subwoofery" to me. This was OK for explosions and so on from movies, but didn't sound correct for music. I got rid of those box woofers and now have 4 Rhythmik servo open baffle 12 inch subs, which don't store nearly as much energy. THis, to me, is a much better match in the time domain with the panels. I cross over at 45 Hz with a 48 dB/octave crossover. Adjusting the phase using measurements has worked OK.
Also, as noted by Siegfried Linkwitz ( https://www.linkwitzlab.com/Sound_field/Field_control.htm ) dipole woofers - which open-baffle subwoofers are - will excite room modes in a less objectionable way, making for a less "lumpy" or "one-note" low end.
Science doesn't care what you believe.
Thanks for the help. It's greatly appreciated. I'm sure I will end up moving them as I play around. Luckily, the JL has a continuous phase adjustment (rather than just a 0/180 switch) so there's a lot of play to it.
In fact, the phase adjustment, at least according to the knob, goes up to 280 degrees.
I have my subs directly behind my 1.6s and they work great. They are crossed over at 60hz through my Denon AVR X3700H. The subs are primarily used for home theater. Subs are set in phase. Subs are JBL SPII. Subs are oriented with the drivers pointing outward away from one another. I have have no problem with any kind of phase cancellation.
'xept my subs were outboard of my Maggies. (I say ' were ' bcoz I moved on from my active Maggies to active 'zero baffle' spkrs that I designed myself.)
The subs are in the front corners of the room; the mains (both Maggies and my new spkrs) are inboard a few feet - therefore closer to my ears.
In my case, as my setup is active ... I can use my miniDSP unit to apply delay to the mains, to time-align them with the subs.
In your case, as I presume your 1.6s are passive - and you're not rolling off the 1.6s ... all you have is your phase control, to achieve the best integration between subs and mains.
You will need a mic and REW on your PC, to be able to set the sub phase correctly.
A better solution IMO is to use a 2-way DSP unit to:
* apply a roll-off to your 1.6s at, say, 60Hz - to match the roll-on of your subs.
* and apply delay to your subs to time-align them with your 1.6s.
Andy
in the crossover region.
Mark in NC
"The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
If possible, try experimenting with one sub in a front wall corner and the others on the opposite side wall out 1/3 the distance from the front wall to the listener.
Gsquared
Yeah, I was debating between REW and something with DIRAC like the new MiniDSP Flex, but thought well, I'll try going without first and save a few bucks.
For now, I'm thinking that I'm willing to DSP the subs if necessary, but want to leave the Maggie signals untouched.
Yes, I'm a somewhat @n@l audio purist...
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