AVS Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
142 Posts
Discussion Starter · #1 ·
I was wondering something , i might buy 2 xv15 in the near future and put them together for a few month until i change for a bigger room ... so yea my plan was to put them together ( side by side ) to do like a xv30... so i was wondering about the phase .. since they next to each other , do i have to leave the phase at the same ( 0 /0 ) or (180/180) ??? or if its possible that one cancel the other ?


how that actualy work ?? how a sub can cancel another one ? when they far from each other ???
 

·
Registered
Joined
·
2,495 Posts
Normally if you have 2 subs both up front they will be phased at 0 degrees. But if you do one sub farfield up front and one sub nearfield you may need the front sub at 0 and the nearfield sub at 180.


The PSA subs have a continuous phase control so anywhere from 0 to 180 which makes it more difficult to figure out, BUT will give you the best results once you do.


For my Outlaw subs at my old house I had 1 up front and 1 next to the couch as an end table (those subs just have a phase switch either 0 or 180 that's it). The front sub was at 0 and the end table sub was at 180. I figured that out using an SPL meter at the MLP and setting the front sub to 0. Then checked the SPL meter with the 2nd sub at 0 and then again at 180 and the SPL was louder with the front sub at 0 and the near sub at 180 so that's how I knew what settings to use.
 

·
Premium Member
Joined
·
14,079 Posts

Quote:
Originally Posted by nemoreborn  /t/1467613/2-subs-phase#post_23186213


I was wondering something , i might buy 2 xv15 in the near future and put them together for a few month until i change for a bigger room ... so yea my plan was to put them together ( side by side ) to do like a xv30... so i was wondering about the phase .. since they next to each other , do i have to leave the phase at the same ( 0 /0 ) or (180/180) ??? or if its possible that one cancel the other ?


how that actualy work ?? how a sub can cancel another one ? when they far from each other ???
If you place the subs right next to each other, (i.e., "co-locate" them), they will acoustically couple and the sound waves will propagate as a single wavefront. They MUST be set to the same phase for this to occur. You'll realize 6 dB of great output capability, (i.e., "headroom"), but you should calibrate them as one sub.


If/when you decide to separate them, you'll want to investigate measurement capability, as optimizing them for phase, level and frequency response will require measurement capability.


Craig
 

·
Registered
Joined
·
6,055 Posts
Setting the distance right is more important than phase. If you have separate distance settings for each sub, set both phases at 0. If you don't, set the phases at 0 and place the 2 subs equidistant from you. If you can't do that, you can try playing around with the phase, but you'll be shooting in the dark. You'll never be able to solve the problem at anything but a single frequency. The phase control on a sub isn't used to integrate multiple subs. It's there to integrate the subs with your front speakers.
 

·
Banned
Joined
·
8,303 Posts

Quote:
Originally Posted by KidHorn  /t/1467613/2-subs-phase#post_23187277


Setting the distance right is more important than phase.

In our case, I spent a great deal of time setting the phase on the three subs and now, distance changes have pretty close to zero impact on subwoofer measurements. A distance change of fifteen feet will show up as nothing more than a background anomaly.


In violations of all the rules, at either the sub or the AVR level, I steer the final graph measurements with the various gain settings.


Unfortunately, for our room, Anti-Mode and Audyssey get the final adjustments, all wrong. And that's not an indictment of either product. In tandem, they do a bang up job of get you to port but one has to become the harbor pilot that gets the measurements to the pier.
 

·
Banned
Joined
·
15,491 Posts

Quote:
Originally Posted by nemoreborn  /t/1467613/2-subs-phase#post_23186213


I was wondering something , i might buy 2 xv15 in the near future and put them together for a few month until i change for a bigger room ... so yea my plan was to put them together ( side by side ) to do like a xv30... so i was wondering about the phase .. since they next to each other , do i have to leave the phase at the same ( 0 /0 ) or (180/180) ??? or if its possible that one cancel the other ?


how that actualy work ?? how a sub can cancel another one ? when they far from each other ???
First off, don't put them together. Put them at opposite ends of the room. As for the phase control, that depends. Some phase controls really are phase controls, all-pass filters which shift the phase of the signal across the entire passband. Some are actually delay controls. When you delay a signal you shift its phase as well, but not by the same degree for all frequencies across the passband. And some are actually polarity switches; if it has only two positions, 0 and 180, it's a polarity switch.


How to set them is a bit of a chore, especially if you don't have measurement gear. First you set the sub closest to the mains, using a sine wave tone though the mains and sub at the crossover frequency, setting the knob to where it sounds loudest. Then you run pink noise through both subs only, setting the knob of the second to where the overall level sounds best at the LP. Getting it more accurate than that requires measuring tools so you can view the result on a response chart.
 

·
Registered
Joined
·
6,055 Posts

Quote:
Originally Posted by Bill Fitzmaurice  /t/1467613/2-subs-phase#post_23187351


As for the phase control, that depends. Some phase controls really are phase controls, all-pass filters which shift the phase of the signal across the entire passband. Some are actually delay controls.

What subwoofers have a phase knob that's actually a delay control?

Does the knob have a distance label or still show a degree label?
 

·
Registered
Joined
·
14,581 Posts

Quote:
Originally Posted by KidHorn  /t/1467613/2-subs-phase#post_23188312


What subwoofers have a phase knob that's actually a delay control?

Does the knob have a distance label or still show a degree label?

my xv15's are adjustable from 0-180° in 15° increments. i think most of the internet direct subs are similar to this, but most of the brick and mortar companies use a 0/180 switch.
 

·
Registered
Joined
·
6,055 Posts

Quote:
Originally Posted by basshead81  /t/1467613/2-subs-phase#post_23188374


my xv15's are adjustable from 0-180° in 15° increments. i think most of the internet direct subs are similar to this, but most of the brick and mortar companies use a 0/180 switch.

A variable phase knob is not the same as a delay knob. The reason I asked is I have never seen a subwoofer amp that had a delay knob. I've seen them on amps, but not subwoofer amps. I wanted to know who supplies a sub with a delay knob as I would find it more useful than a phase knob.
 
1 - 9 of 9 Posts
Top