Cool way to set the phase of your subwoofer correctly . . .

SolidSqual

First, get a Test tone CD that has a tone for the point at which your sub and main speakers are crossed over.

Second, completely power down your system and flip the polarity of your speakers cables. Plug the black into the red post and vice versa.

Third, play the test tone of the 60Hz test tone for example through the speakers.

Fourth, have someone turn the phase dial slowly as you listen from the sweet spot. When you hear the absolute least bass, then you have found the best point of phase correction for your subwoofer. Here, with your speaker polarity flipped, you have found the exact point where your subwoofer driver is moving out and your speaker drivers are moving in.

Fifth, power down the system and return the speaker cables back to their proper positions.

Sixth, listen and enjoy.

This is the most accurate and easiest way I have ever set up my sub. By flipping the speaker polarity and listening for the point at which the phase produces the least bass, you effectively find the frequency at which both bass signals are cancelled. Flipping the speaker back to the correct wiring, places the entire system in perfect phase and you have smooth and seamless bass. I found this method much easier to do because it's easier to hear the absence of bass than to try and distinguish peaks.

Good luck! Let me know if you have the same results as I did.

millerman 3732

cool, I'll try it.

Face

SolidSqual wrote: »

Here, with your speaker polarity flipped, you have found the exact point where your subwoofer driver is moving out and your speaker drivers are moving in.

I'm not a expert on this, but it sounds like once your speaker cables are put back to normal, they would cancel each other out. Also, wouldn't the sub's placement in the room also have a effect on this method? I'll have to try this out for myself later this week.

Btw, my sub was set by trial and error via room-eq wizard.

SolidSqual

Why would the main speakers cancel each other out after returning the cables to their correct locations . . . that's the way they were designed to operate?

Also, I think by switching the speakers back to normal operation, you invert the phase to match that of the sub. Thus, they strengthen each other.

Music Joe

What a slick and simple way to hone in on the 180 degree - point, thanks.

zingo

That is a great idea and real simple. Thanks!

SolidSqual

Bear in mind that this little trick is only for phase correction, not placement. You do this after the subwoofer is placed in the optimal position. Then adjust volume accordingly.

Systems

This may be helpful if your sub has a 0-180 degree variable phase adjustment.If it just has a simple 0/180 phase switch or a full 0-360 degree adjustment there would be no need to reverse the speaker connections.The position of the switch (or control) that results in the most bass when playing test tones is the correct position.

SolidSqual

GV#27 wrote: »

This may be helpful if your sub has a 0-180 degree variable phase adjustment.If it just has a simple 0/180 phase switch or a full 0-360 degree adjustment there would be no need to reverse the speaker connections.The position of the switch (or control) that results in the most bass when playing test tones is the correct position.

I agree partially with you. It is less helpful with a phase switch, but just as helpful with a full 360 knob. As I indicated before it's much easier to listen for lack of bass. If you were to do the same with the speakers unflipped, you would be listening for the peaks which are harder to hear or you would find the point where the bass is the least and then set the knob 180 degress from that.

Systems

SolidSqual wrote: »

It is less helpful with a phase switch, but just as helpful with a full 360 knob. As I indicated before it's much easier to listen for lack of bass.

Your method is great and agreed it is easier to hear nulls than peaks.However with the phase switch and 0-360 reversing the speaker conections is not necessary as flipping the switch achieves the same thing.With the 360 control you can turn it until you get the biggest null then turn back exactly 180 degrees and your back in phase.

SolidSqual

GV#27 wrote: »

Your method is great and agreed it is easier to hear nulls than peaks.However with the phase switch and 0-360 reversing the speaker conections is not necessary as flipping the switch achieves the same thing.With the 360 control you can turn it until you get the biggest null then turn back exactly 180 degrees and your back in phase.

That's true.

kuntasensei

Something worth mentioning: Set subwoofer distance/delay relative to the other speakers BEFORE doing this. Distance settings for the sub effectively act as a variable phase control, so I'd set it to the actual physical distance. You also have to consider group delay caused by the signal chain (especially if you're using an in-line EQ or an active crossover on the subwoofer itself, which you should be defeating in most setups).

Gaara

Sound like someone has been reading Robert Harley. Two things:

1) IMO it would be better to use a SPL meter then you rear, as the equipment will be more sensitive to small changes. Your ear can get you close, using a SPL will perfect the adjustment.

2) Try different frequencies. Not sure what causes it (group delay?) but many times your speakers/sub will be in phase at certain frequencies but out of phase at others. Try playing something at 80hz and measure with the SPL meter, then turn the sub off, you may be surprised.

You want phase set where the frequency response is flattest. Just because you are in phase at the x-over point other frequencies may be way out of wack. You may use this to your advantage, ex. you have a big peak at 80hz, setting the phase so it is slightly out of phase at 80hz could be beneficial. This adjustment is totally system dependent.

SolidSqual

Good Point.

I do read TAS but never an article on this by RH. A bud of mine in Cleveland let me in on this little trick. Don't know where he go it, I just assumed from experience installing gear for a living.

Gaara

SolidSqual wrote: »

Good Point.

I do read TAS but never an article on this by RH. A bud of mine in Cleveland let me in on this little trick. Don't know where he go it, I just assumed from experience installing gear for a living.

Didn't even realize he was the editor for TAS. I was referring to "The Complete Guide to High-End Audio". I read it cover to cover before I got into the hobby, always figured it was required reading.