[Davy]

I have stereo speakers powered by an amp; an active centre speaker
running off a stereo mixer to mono box and an active mono sub-woofer -
all by different manufacturers and vintage.

How can I make sure that they are in phase and not cancelling each other
out? There are plently of test tracks with which I can test the stereo
speakers - but I don't know how to test the whole system.
Any thoughts?
DAvy

[[email protected]]

To put each amp speaker pair in the same "phase":

Using a battery test which wire produces the same forward or backward
pulse. When each wire pair is tested connect to the same terminal on each
amp accordingly.

[Arny Krueger]

"Davy" wrote in message
...

I have stereo speakers powered by an amp; an active centre speaker
running off a stereo mixer to mono box and an active mono sub-woofer -
all by different manufacturers and vintage.

How can I make sure that they are in phase and not canceling each other
out? There are plenty of test tracks with which I can test the stereo
speakers - but I don't know how to test the whole system.

Set your system up so that you are playing exactly the same music at the
same loudness through each and every speaker. The source should be mono.

Then walk around the room, standing between the speakers in pairs. You
should be able to position yourself so that the sound appears to be coming
from a virtual image between each pair of speakers.

This may be hard to do with the subwoofer. Check its polarity by trying both
polarities and picking the one that gives you the best bass.

[Walt]

wrote:
To put each amp speaker pair in the same "phase":

Using a battery test which wire produces the same forward or backward
pulse. When each wire pair is tested connect to the same terminal on each
amp accordingly.


This will work, if none of the other components in the signal chain
invert polarity. If they do, you'll have to take that into account.

//Walt

[Davy]

wrote in :

To put each amp speaker pair in the same "phase":

Using a battery test which wire produces the same forward or backward
pulse. When each wire pair is tested connect to the same terminal on
each amp accordingly.


Unfortunately can't do that cos the sub-woofer and the centre speaker
are active - i.e. have built-in amps.

DAvy

[Sonnova]

On Wed, 10 Jun 2009 07:24:37 -0700, Arny Krueger wrote
(in article ):

"Davy" wrote in message
...

I have stereo speakers powered by an amp; an active centre speaker
running off a stereo mixer to mono box and an active mono sub-woofer -
all by different manufacturers and vintage.

How can I make sure that they are in phase and not canceling each other
out? There are plenty of test tracks with which I can test the stereo
speakers - but I don't know how to test the whole system.

Set your system up so that you are playing exactly the same music at the
same loudness through each and every speaker. The source should be mono.

Then walk around the room, standing between the speakers in pairs. You
should be able to position yourself so that the sound appears to be coming
from a virtual image between each pair of speakers.

This may be hard to do with the subwoofer. Check its polarity by trying both
polarities and picking the one that gives you the best bass.


I'd leave the subwoofer DISCONNECTED for Arny's phase test. After you are
sure that the left, right, and center speakers are all in-phase, then connect
your sub and try reversing the polarity. The polarity that gives the best
bass will be proper, irrespective of it's electrical phase in relationship
with the other speakers.

[Drew Eckhardt]

On Jun 8, 4:04*pm, Davy wrote:
I have stereo speakers powered by an amp; an active centre speaker
running off a stereo mixer to mono box and an active mono sub-woofer -
all by different manufacturers and vintage.

How can I make sure that they are in phase and not cancelling each other
out? *There are plently of test tracks with which I can test the stereo
speakers - but I don't know how to test the whole system.
Any thoughts?
DAvy

Gross problems can be detected by a test DVD like Avia and you can
invert polarity of the passive speakers to correct. Most sub-woofers
have a phase switch, and if not it should be easy enough to reverse
the leads inside.

You can't get away from lesser problems without making more serious
equipment changes.

Without using linear phase digital filters, filler drivers, or first
order cross-overs your speakers have an all-pass response. Second
order cross-overs are first order all-pass filters with 0 to 180
degrees of phase shift. Fourth order cross-overs have 0 to 360
degrees of phase shift. Where the center and mains aren't identical
in driver compliment and cross-over frequencies+slopes they're not
going to sum the same at different frequencies.

Low-frequency roll-off can have some effect too, with the speakers'
minimum phase high-pass response implying phase lead.

[Greg Wormald[_2_]]

On Jun 8, 4:04*pm, Davy wrote:
I have stereo speakers powered by an amp; an active centre speaker
running off a stereo mixer to mono box and an active mono sub-woofer -
all by different manufacturers and vintage.

How can I make sure that they are in phase and not cancelling each other
out? *There are plently of test tracks with which I can test the stereo
speakers - but I don't know how to test the whole system.
Any thoughts?
DAvy

The standard test for system polarity is to play some music with a known
good bass line. Reverse the connections to one of the speakers and the
connection that provides the maximum bass is the correct polarity.

Greg

[Greg Wormald[_2_]]

On Jun 8, 4:04*pm, Davy wrote:
I have stereo speakers powered by an amp; an active centre speaker
running off a stereo mixer to mono box and an active mono sub-woofer -
all by different manufacturers and vintage.

How can I make sure that they are in phase and not cancelling each other
out? *There are plently of test tracks with which I can test the stereo
speakers - but I don't know how to test the whole system.
Any thoughts?
DAvy

The standard test for system polarity is to play some music with a known
good bass line. Reverse the connections to one of the speakers and the
connection that provides the maximum bass is the correct polarity.

Greg