# 2 sub phase adjustment



## jwhite8086 (Feb 4, 2007)

How do I detemine the proper phase adjustment of my two pb10s ?


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## bpape (Sep 14, 2006)

The easiest way:

Play a pure tone at your xover frequency. Use the mains and just one sub to start with. Using an SPL meter at the seating position (and with your subs in their final position), adjust phase until you get the max output level.. 

Repeat using the other sub.

Bryan


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## Ethan Winer (Jul 21, 2006)

bpape said:


> Repeat using the other sub.


Yes, and probably repeat both subs once or twice more too, since phase adjustments can interact.

--Ethan


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## jwhite8086 (Feb 4, 2007)

Where do I get the pure tone from?


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## bpape (Sep 14, 2006)

Ethan Winer said:


> Yes, and probably repeat both subs once or twice more too, since phase adjustments can interact.
> 
> --Ethan


Right. Guess I wasn't clear. The idea was to do the 2nd one with the mains and 1st sub both already on so you're blending the 2nd sub with what you already did.

You can get a bunch of free tone generators off the web and run out of your PC. I believe Ethan still has some on his site too ready for download.

Bryan


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## brucek (Apr 11, 2006)

One of the problems with the single tone method is that you could be adding to an existing peak at the crossover frequency that makes the situation worse.

A better method would be sweep the sub and mains with REW software and adjust the phase controls for a smooth transition at the crossover.

At minimum you need to test with multiple tones above and below the crossover to be sure you're not simply creating a peak with the phase controls..

brucek


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## jwhite8086 (Feb 4, 2007)

So i can use rew , when I get some time alone I want to save measurments of one sub two sub in a couple of locations . Its imposible to do this with wife and kids home.


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## bpape (Sep 14, 2006)

brucek said:


> One of the problems with the single tone method is that you could be adding to an existing peak at the crossover frequency that makes the situation worse.
> 
> A better method would be sweep the sub and mains with REW software and adjust the phase controls for a smooth transition at the crossover.
> 
> ...


Agreed. You may need to adjust from perfect phase later on. However, IMO it's important to get everything in the proper phase to start with and then adjust later if necessary. Adjusting peak at xover via the phase control is a tradeoff IMO of better FR for muddier bottom end. I'd prefer to get the phase correct and then lower the xover point on the sub so you leave a gap between the mains xover and the sub xover to deal with any peak. Using phase for that is usually my last resort.

Bryan


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