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Electro-Voice
®
11
System shuts down when driven hard.
1.) Insufficient amplifier power. Amplifier goes into protect mode
due to overcurrent or thermal stress. Switch to a larger
amplifier.
2.) Line impedance too low. (PI models in particular) Some
amplifiers will not drive a 2 ohm load at full power, especially if
both channels are loaded to 2 ohms. (A pair of Sx600PI
systems on the same line is a 2 ohm load.) Use a different/
bigger amplifier, convert to PIX versions, or reconfigure lines
with more amp channels and fewer speakers per line.
3.) Incorrect high-pass filter or no filter at all. All Sx600 models
MUST BE HI-PASSED, (See step 5 above) but PIX models may
cause amplifier shut-down due to transformer saturation at high
levels caused by low frequency transients or heavy bottom
octave program content. Verify that the CORRECT hi-pass
filtering is in use at all times.
4.) Amplifier is simply being overdriven and going into protect mode.
With an oscilloscope on the amplifier output, adjust compressor/
limiter to keep amplifier(s) out of clipping. If the system has no
comp/limiter, add one to the signal chain and be sure it is
properly set.
Inconsistent intelligibility in audience area
1.) Improper aiming. If intelligibility decreases near the speaker, the
down-angle is set too high. If the intelligibility is great right under
the speaker but suffers as you begin to move away from it, the
down-angle is set too low. Intelligibility across the horizontal
plane (side to side) can be affected by a sloping audience area,
reflections from nearby walls or other barriers, and trees,
banners and other objects obstructing and/or reflecting the
sound in an adverse way. EASE is an excellent tool for
predicting the correct aiming, but in actual use these angles may
need to be adjusted.
2.) Over-equalization. The primary speech fundamentals are found
in the 300Hz to 3kHz range, most consonants are affected by
the 3kHz to 6 kHz band, and sibilance is mostly from 6kHz on
up. Substantial EQ cuts in any of these regions will seriously
degrade the intelligibility of speech. Use only enough EQ to
tame the very worst room resonances (which should not be a
problem outdoors) keeping the notch width as narrow as
possible. The best solution is to keep the announcer close to