Sub Phase

[bongobob]

I've read in various threads where phase should be adjusted until you acheive the best blend with the other speakers and the best bass response. Isn't the goal to have the driver moving forward at the same time as the drivers in the mains?
I have ports in my sub and noticed that by suspending a piece of light fabric over the ports that the fabric would suck into the ports a bit when receiving LFE info in time with the rest of the music, indicating the sub was "in phase".
Does this seem like a valid observation to anyone? I was wondering whether this method might eliminate some of the guesswork when tuning in a sub, at least for theose whose subs have ports........

 

[j_garcia]

"In" phase is determined by placement of the sub within the room relative to the other speakers and your listening position. So phase should be adjusted to whichever gives you the best sound. In most cases, "0" will work fine.

 

[bongobob]

Does sub phase act the same as say, having one speaker with the polarity switched at the terminals, thus putting it out of phase? In that condition if you have the same signal coming through the L+R mains with one channel being out of phase I believe you would have some cancelation of the signal.
The question is in what possible circumstances would you want the driver to be retracting while the rest of the speakers were pushing?

 

[j_garcia]

If you have the main speakers in the front of the room and the sub on the opposite end, you may get enough of a timing issue where phase could be of use. It isn't just when the drivers are moving, but when the sound is arriving at your ear.

 

[rynberg]

Changing the phase is NOT the same as reversing the polarity, despite the very common mis-use of these terms. Even audio professionals who should know better make this mistake.

It is important to realize that changing the phase only affects the timing (phase) at the crossover frequency. Below the x-over freq, the phase will change depending on the order/type of the x-over. You should adjust the crossover so the sound level at the x-over freq is loudest.

 

[Buckeye_Nut]

If you have the main speakers in the front of the room and the sub on the opposite end, you may get enough of a timing issue where phase could be of use.

My understanding is that front or back doesnt matter. It's only the distance from your ears that matters

By inputting correct speaker/sub distances into your receiver/processor, in theory.... you shouldnt have phase issues.

 

[ggunnell]

Buckeye, I've read the opposite -- that a common misconception is that a set millisecond delay for all frequencies (speaker distance adjustment) is the same as a sub's phase adjustment. I'll see if I can find the posts....

I've also read different things about the range of frequencies affected by the phase control -- and I've definately read enough about plate amps to know that how well features like this are implemented varies a lot.

What I do know from personal experience is that I have not been able to get nearly as good a combined bass sound from subs and speakers using distance compensation alone as I have using phase controls alone -- using both together is best, of course.

I won't by a sub anymore that don't have a continuously variable phase control.