Phase switch

jwienand

What is different between 0 and 180?

Eman

Sometimes Bass from the Front or Left (or other large speakers in your system) can interfere with the Bass from the Subwoofer so a swithch is provided to have them be out of phase.

When installing a sub you will find that Bass output varies not only with placement but with phase so pick the best location based on this. Trial and error but normally as you may know subs perform good in corners and or other boundaries where walls meet.

RuSsMaN

The difference is the woofer moving in or out first. It would be the same as switching your pos/neg wires on the back of your main speakers.

The bass doesn't 'interfere' from the main speakers, the problem you can run into is phase inverting preamp and amp stages in a receiver (and some separates). Most people don't know if their system does it or not. The phase switch allows you to compensate, if something in your system is in fact inverting phase.

Cheers,
Russ

aaharvel

Russ. +1

Eman

RuSsMaN wrote:

The difference is the woofer moving in or out first. It would be the same as switching your pos/neg wires on the back of your main speakers.

The bass doesn't 'interfere' from the main speakers, the problem you can run into is phase inverting preamp and amp stages in a receiver (and some separates). Most people don't know if their system does it or not. The phase switch allows you to compensate, if something in your system is in fact inverting phase.

Cheers,
Russ

For the sake of the first post I will write the following:

According to the laws of physics all waves by their nature can interfere even so for acoustic/compressional waves one way to prevent this is to have waves be out of phase. The subwoofer phase switch allows you to do this if its necessary but will depend on its location or placement. The way these waves are generated is an entirely separate issue.

RuSsMaN

Wrong again.

Subwoofer placement in any given room has NOTHING to do with the phase. Placement is important, but has nothing to do with phase.

As I said earlier, the phase switch is there to MATCH THE PHASE OF THE REST OF THE SYSTEM. Some pre and main amplifier stage designs are phase inverting. One could even have BOTH a preamp and main amp stage that invert phase, and end up right back in absolute phase.

The easy test for which setting you should is one should have more/better bass. Why? Simple, that is the setting that is IN PHASE with the rest of the system. The setting with less bass will be OUT OF PHASE with your system. Why? Again, simple - you are experiencing cancellation at certain frequencies.

Thanks for playing.

Eman

RuSsMaN wrote:

Wrong again.

Subwoofer placement in any given room has NOTHING to do with the phase. Placement is important, but has nothing to do with phase.

As I said earlier, the phase switch is there to MATCH THE PHASE OF THE REST OF THE SYSTEM. Some pre and main amplifier stage designs are phase inverting. One could even have BOTH a preamp and main amp stage that invert phase, and end up right back in absolute phase.

The easy test for which setting you should is one should have more/better bass. Why? Simple, that is the setting that is IN PHASE with the rest of the system. The setting with less bass will be OUT OF PHASE with your system. Why? Again, simple - you are experiencing cancellation at certain frequencies.

Thanks for playing.

Yes you are right of course. Thank You.

JHONE

I'm just wondering what is the significance of 4 phase control adjustments. My sub is out of phase with the sub's phase adjustment at either 0 or 90. Phase is ok at either 180 or 270.

My only logical conclusion (which probably is wrong) is that the sub is out of phase entirely at 0 but just a bit at 90 while 180 gives the best "in" phase control while 270 is basically ok too.

Thoughts?

jwienand

Thanks for the info guys.

tenor12

RuSsMaN wrote:

Wrong again.

Subwoofer placement in any given room has NOTHING to do with the phase. Placement is important, but has nothing to do with phase.

As I said earlier, the phase switch is there to MATCH THE PHASE OF THE REST OF THE SYSTEM. Some pre and main amplifier stage designs are phase inverting. One could even have BOTH a preamp and main amp stage that invert phase, and end up right back in absolute phase.

The easy test for which setting you should is one should have more/better bass. Why? Simple, that is the setting that is IN PHASE with the rest of the system. The setting with less bass will be OUT OF PHASE with your system. Why? Again, simple - you are experiencing cancellation at certain frequencies.

Thanks for playing.

Well, under certain conditions sub placement could be important for phasing, particularly if the sub is much closer or farther away from the listening position than the main speakers. Consider a system where the main speakers are 8 feet farther away from the listening position than the sub, and both the sub and main speakers are emitting significant sound energy at 60 Hz, which is not unreasonable to assume for at least some systems. A 60 Hz sound wave has a wavelength of approximately 16 feet, so the differences in speaker distances is about 1/2 wavelength. Therefore 60 Hz waves that start out in phase have different distances to travel, and will be out of phase when they reach the listener, leading to a dip in frequency response at 60 Hz. With this arrangement an reversal in polarity may yield more pleasing results (or maybe even a response rise at 60 Hz, due to reinforcement).

mantis

Basically from my experience here what works most of the time..

0 or no phase in the front of the room.

90 on side walls

180 in back of room.

This has worked for me in all kinds of different setups and subwoofers

Dan

unc2701

Eman and Russman are both right- the power section of an amp can reverse the phase (and this effect was probably the origin of the phase switch) however, the distance from the mains and room dynamics can also cause speakers to be out of phase with respect to the listener.

Otherwise:
1)there'd be no subs with 90 and 270 degree phase (or variable, for that matter)
2)there'd porbably be no subs with any phase switch at all since about 90% of recievers made today are based on the same design and we all know how manufacturers like to make things cheaper.

I moved a sub from behind the couch to behind the TV and what do you know?... the phase switch was better in the other position.

jwienand

0 phase at the front of the rooom definately sounds better Mantis.