Setting Phase on Dual PB12NSD

[Fowl]

Hi Guys,

As the subject of my thread implies, I am looking for a article or suggestion on setting the phase on my dual PB12NSD sub in my room. I have been battling with this for sometime but never seem to get it perfect. Both of my subs a directly infront of the listening position and same distance from the listening position.

Could you explain of direct me to a easy to understand article here.

 

[Basshead81]

Really the only way to do this correctly is by downloading a freeware copy of REW and purchase a usb measuring mic. This way you can physically see how adjusting the phase effects the FR. Also if your AVR does not have dual sub eq capability then you may need a eq device that is equipped with individual delay settings for each sub in order to get it perfect.

On a side note, subs that are placed within a 1/4 wavelength from each usually require the phase to be the same. Now If you have a sub placed across the room then one may need to be reversed 180.

All that being said it sounds like your delay settings are slightly off rather then it being a phase issue.

 

[j_garcia]

http://forums.audioholics.com/forums/subwoofers/65220-home-theater-multiple-subwoofer-set-up-calibration-guide.html

 

[Ed Mullen]

When the subwoofers are on the same plane and also the same distance to the listening position, there is no need to individually phase them with respect to each other. The subwoofer distance control is the preferred method to time-align the subwoofers with the speaker channels.

The distance control is preferable to the phase control because it digitally delays the signal uniformly across the entire pass band of the speaker or subwoofer. The subwoofer phase control (in comparison) has the most effect at a single frequency (usually 80 Hz), and progressively less effect at deeper frequencies.

I only recommend using the phase control when there are dual subs being fed by a single AVR output, and one of the subs is closer to the listening position than the other. In that case, the phase control can be used on the closer subwoofer to delay the signal on the closer subwoofer such that it better time-aligns/phases with the farther subwoofer. Then the single subwoofer distance in the AVR will be more valid for both subs.

 

[ousooner2]

As far as 'distance' in the AVR calibrations, how does one know if the AVR has set it correct or close to correct? I know it's not a physical distance measurement, but an acoustic one. I've always wondered if it would have any effect if Audyssey MultEQ XT was off for my dual sub setup and I could correct it or get it 'better' somehow...just didn't want to start messing with it and mess something up.

Which brings me to my next question....the 'distance' would only be valid for a certain frequency also correct? I know the waves are longer down low so you're phase won't be 180 off like it could be at higher frequencies when taking into account an octave difference, but at what frequency do you want to try to get the distance correction the closets for? At the crossover? 40hz-ish (most people's 'middle' area between their lowest low and highest freq. on the sub)? I guess I could bring the SPL meter out and just keep playing with the distance until I find the highest SPL number, but again...not sure what frequency I should be looking at. Maybe pink noise through the entire band...or sine wave through the entire band and unplug the other speakers for the test.

 

[Basshead81]

As far as 'distance' in the AVR calibrations, how does one know if the AVR has set it correct or close to correct? I know it's not a physical distance measurement, but an acoustic one. I've always wondered if it would have any effect if Audyssey MultEQ XT was off for my dual sub setup and I could correct it or get it 'better' somehow...just didn't want to start messing with it and mess something up.

Which brings me to my next question....the 'distance' would only be valid for a certain frequency also correct? I know the waves are longer down low so you're phase won't be 180 off like it could be at higher frequencies when taking into account an octave difference, but at what frequency do you want to try to get the distance correction the closets for? At the crossover? 40hz-ish (most people's 'middle' area between their lowest low and highest freq. on the sub)? I guess I could bring the SPL meter out and just keep playing with the distance until I find the highest SPL number, but again...not sure what frequency I should be looking at. Maybe pink noise through the entire band...or sine wave through the entire band and unplug the other speakers for the test.

You need to invest in a measuring mic and download a freeware copy of REW as I previously mentioned. Makes setting up a system so much easier. The distance setting effects the subs entire FR range to the crossover point, the phase dial effects around the crossover region only. Generally AVR correction software can get it close and if duals are equidistant from the LP, most AVR's(not xt32 equipped) can still get both subs set correctly. Read ED's post again, he just explained it to a T.