System Phasing - zapco ST-X DSP Owner's Manual

System Phasing: Before you start the equalization you want to be sure the system
is phased properly. Below we offer one system to help you phase the system.
You were promised more on polarity. Before equalization you should assure
that all speakers are in phase as a system at the listening position. All speakers
need to have the same polarity so they move the same direction at the same
time. If they are not, you will not be able to get a proper tune. There are a
number of methods for doing this. We offer one.
Tweeters: (A) Mute all speakers except the tweeters and play a high female
vocal soloist. You should hear the voice at a single point near upper middle of
the windshield. If the speakers are out of phase the voice will not be localized
but will seem to come from everywhere. To test, using the Phase buttons,
change the phase of the right speaker and listen for the difference. Do this a
couple of times as needed. The position that puts the voice in a small single
location on the window is the correct phase. (B) Note where the Tweeter center
is located. It should be just slightly above and to the left of the center of the
windshield (for left hand drive cars). If it is off to the opposite side of center or
too far to the left, and if you have measured correctly, then you have a gain
difference and you can correct by a slight level adjustment reduce the right
tweeter to bring it left or reduce the left channel to take it right. No more that
1dB or 2dB. Now the tweeters are set. From here on out you cannot change the
levels or phase of either tweeter.
Mids, Mid-bass (woofers), and
midranges. The process is the same for each pair of speakers. The sound should
come from a single focused point near the center of the windshield. For
midranges and larger drivers, you want to use a deeper male vocal. The larger
drivers are much easier to tell the differences between in-phase and out of
phase. Also, with the larger speakers you will hear a dramatic reduction of bass
if the speakers are out of phase. So, for midrange and larger speakers you will
look for a focused sound source in the windshield with stronger bass.
NOTE: Once each channel pair is adjusted, they cannot be separated. Any change of phase must
be done by the pair.
Phasing the pairs: Again, listening to a single vocalist. Mute all channels again
except the tweeters. Then bring in the midranges. If these pairs are in proper
phase the sound should be near center in the upper part of the windshield. If
they are not in phase the sound will be pulled down lower. You can reverse the
phase of BOTH mids now and listen for the difference in the sound location.
Choose the phase position that puts the sound high near the center.
subs: Now mute the tweeters and un-mute the
22