Why do you need a phrase switch on a sub woofer

Archived from groups: rec.audio.tech (More info?)

Brian wrote:
> I'd be interested in knowing more about the phase switch. The manual
> for the sub woofer does not explain the purpose of this switch.
>
> Regards Brian
Here's a non technical attempt. Depending on what kind of satellites
you have they will have different types of crossovers in them. Usually
these are second order or third order, 12 dB slopes or 18 dB slopes.
This in addition to the sub not being necessisarily in the same plane
with the satellites and that the crossover to the sub from the
satellites is going to have it's own slope. In other words unless the
system is put together as a whole from the manufacturer in order to
assure proper matching to the rest of the system a phase switch is
needed so that the speakers in the system are all in phase with each
other. I'm sure there will be a lot more technically correct and
detailed responses to follow.

Archived from groups: rec.audio.tech (More info?)

On Fri, 25 Mar 2005 12:55:00 +1200, Brian <bclark@es.co.nz> wrote:
>I'd be interested in knowing more about the phase switch. The manual
>for the sub woofer does not explain the purpose of this switch.

Unless your subwoofer is in the *exact* place as your satellite speakers,
literally overlapping the same space, given the speed of sound then its sound is
going to arrive at your ears at a different time than your main speakers.

At the frequency of crossover between sub and mains, the wavelength will be
around 15-25'. If the sub is put 180 out of phase, it'll arrive in phase with
the sound waves from the mains if it is 7-12' away from the mains. Nothing is
perfect; try both settings and see if you can hear any difference and what
sounds better.