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9
Verifying Driver Polarity
Incorrect driver polarity impairs system performance and
may damage the drivers. All Meyer loudspeakers are shipped
with the drivers in correct alignment.
Polarity In Adjacent Loudspeakers
Use the following test procedure to verify the polarity be-
tween two USW-1P.
1. Establish a reference USW-1P, a speaker that has not
been tampered with or damaged. Mark this speaker as
the reference.
2. Place the USW-1P you want to test next to the reference
USW-1P.
3. Place a measurement microphone 3 feet from the speak-
ers on the axis between the speakers. See drawing at
bottom of page.
4. Connect a signal source to reference speaker and note
the frequency response and overall level.
5. Apply the same signal to the USW-1P under test with
the first speaker still connected.
The polarity is correct if the frequency response remains
constant with a 5 to 6 dB SPL increase in amplitude. Broad-
band cancellation (decreased overall level) indicates polarity
reversal between cabinets. A 2 to 3 dB SPL increase may
indicate that one of the drivers in the USW-1P under test is out
of phase, in this case, proceed to the next section.
Since polarity reversal causes excessive driver
excursion at high source levels, use moderate
levels when conducting these tests.
Polarity within a USW-1P
If the driver or circuit wiring has been removed or disas-
sembled it is essential to check the polarity between drivers
and between adjacent loudspeakers.
Use the following test procedure to verify polarity between
drivers in the same loudspeaker :
1. Place the reference USW-1P and the USW-1P under
test side to side so that the drivers are facing the same
direction.
2. Place a measurement microphone 3 feet from the
speakers on the axis between the speakers. See draw-
ing at bottom of page.
3. Connect a full range signal to the reference USW-1P
loudspeaker and note the frequency response and
sound pressure level.
4. Compare the reference and test USW-1P results
one at a time. A significant decrease in energy from
40 to 100 Hz in the USW-1P under test indicates a
driver reversal. Contact Meyer Sound Technical
Support for information on Service Center or field
correction.
5. If the reference and USW-1P under test have similar
responses, then there is no internal polarity error within
the loudspeaker.
3 feet
Reference
USW-1P
Front of Speaker
Front of Speaker
Microphone
USW-1P
under test