Meyer Sound UMS-1P - Manuel (Page 8)

Polarity
With the UMS-1P in close-proximity to,
and coplanar with, the UPM-1P or other
Meyer Sound loudspeakers, all units
should be set to the same polarity.
Separating the subwoofers from the
main cabinets in a loudspeaker system
by more than 5 feet may require polari-
ty reversal or a delay line to compen-
sate for the propagation delay between
the loudspeakers and the measurement
position.
Measurement and Correction
Tools
It is recommended that even the most
carefully assembled sound systems be
analyzed with precise measurement
tools. We recommend using the Meyer
Sound SIM® System II Sound Analyzer
and CP-10 Parametric Equalizer to:
• choose, place, and array loudspeakers;
• measure propagation delays between
loudspeakers to set the correct polari-
ty and delay times;
• measure and equalize variations in fre-
quency response caused by the
acoustical environment and the place-
ment and interaction of loudspeakers.
8
VERIFYING DRIVER POLARITY
Incorrect driver polarity impairs system
performance and may damage the dri-
vers. All Meyer Sound loudspeakers are
shipped with the drivers in correct
alignment.
Polarity In Adjacent
Loudspeaker Systems
Use the following test procedure to veri-
fy the polarity between two UMS-1Ps.
1. Establish a reference UMS-1P, a loud-
speaker that has not been tampered
with or damaged. Mark this loud-
speaker as the reference.
2. Place the UMS-1P you want to test
next to the reference UMS-1P.
3. Place a measurement microphone 3
feet from the loudspeakers on the
axis between the loudspeakers. See
thedrawing on this page.
4. Connect a signal source to the refer-
ence loudspeaker and note the fre-
quency response and overall level.
5. Apply the same signal to the UMS-1P
under test with the first loudspeaker
still connected.
The polarity is correct if the frequency
response remains constant with a 5 to 6
dB SPL increase in amplitude. Broadband
cancellation (decreased overall level)
indicates polarity reversal between cabi-
nets. A 2 to 3 dB SPL increase may indi-
cate that one of the drivers in the UMS-
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 moder-
ate levels when conducting
these tests.
Polarity within a UMS-1P
If the driver or circuit wiring has been
removed or disassembled it is essential
to check the polarity between drivers
and between adjacent loudspeakers.
Use the following test procedure to veri-
fy polarity between drivers in the same
loudspeaker:
1. Place the reference UMS-1P and the
UMS-1P under test side to side so
that the drivers are facing the same
direction.
2. Place a measurement microphone 3
feet from the loudspeakers on the
axis between the loudspeakers.
3. Connect a full range signal to the ref-
erence UMS-1P loudspeaker and note
the frequency response and sound
pressure level.
4. Compare the reference and test UMS-
1P results one at a time. A significant
decrease in energy from 40 to 100Hz
in the UMS-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 UMS-1P under
test have similar responses, then
there is no internal polarity error
within the loudspeaker.
!
Reference
UMS-1P
UMS-1P
Under Test
3 Feet
F
ront of speak
er
F
ront of speak
er
The VX-1:
The VX-1 is an ideal control option for
loudspeaker systems incorporating the
UMS-1P. The VX-1 is a stereo virtual
crossover which allows the user to
adjust the gain, switch between stereo
and mono distribution of two inputs and
make shelving EQ adjustments to the
left and right sides of the system.
Separate Feeds:
One simple method of attenuating the
UMS-1P is to feed separate signals to
the subwoofer(s) and to the main loud-
speaker(s). With independent control of
the main outputs and sub levels, their
relative proportions can be adjusted.
The Looping, Polarity, and
Attenuating Audio Input
Module:
This optional module, described on page
6 of this manual, allows for level control
on the user panel of the UMS-1P.
UMS-1P with the UPM-1P for Music
Monitoring and Listening Purposes
Because of the flatter phase and fre-
quency response of our UltraSeries prod-
ucts, (similar to the HD Series studio
monitors) the teaming of a UMS-1P with
two (in stereo) or more UPM-1Ps (such
as 5.1 surround sound applications) can
be a great choice for high definition
music monitoring. The wider coverage
pattern also helps give listeners better
imaging in stereo and 5.1 playback
without the over-localization which can
plague the near field with a narrower
horn loaded product.
SUBWOOFER LEVEL CONTROL