Meyer Sound Amie-Sub, Руководство по эксплуатации

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CHAPTER 3: AMPLIFICATION AND AUDIO CONNECTORS
The Amie-Sub drivers are powered by a proprietary
open
- loop, class D amplifier. The audio signal is processed
with electronic crossover, and correction filters for flat phase
and frequency responses, and by driver protection circuitry.
The amplifier has peak and rms limiters that prevent driver
over-excursion and regulate voice coil temperatures.
The standard Amie-Sub user panel (Figure 10) includes
3
- pin XLR-F Input and 3-pin XLR-M Loop output connectors
for audio, and Limit and Active LEDs.
Audio Input (XLR 3-Pin Female)
The XLR 3-pin female Input connector accepts balanced
audio signals with an input impedance of 10 k
Ω
. The
connector uses the following wiring scheme:
•
Pin 1 — 1 k
Ω
to chassis and earth ground (ESD
clamped)
•
Pin 2 — Signal (+)
•
Pin 3 — Signal (–)
•
Case — Earth (AC) ground and chassis
Pins 2 and 3 carry the input as a differential signal. Pin 1 is
connected to earth through a 1 k
Ω , 1000 pF, 15 V clamped
network. This circuitry provides virtual ground lift for audio
frequencies while allowing unwanted signals to bleed to
ground. Make sure to use balanced XLR audio cables with
pins 1–3 connected on both ends. Telescopic grounding is
not recommended and shorting an input connector pin to
the case may cause a ground loop, resulting in hum.
TIP: If the loudspeaker produces unwanted
noise or hiss, disconnect its input cable. If the
noise stops, there is most likely nothing wrong
with the loudspeaker. To locate the source of the
noise, check the source audio, AC power, and
electrical ground.
Audio Loop Output (XLR 3-Pin Male)
The XLR 3-pin male Loop output connector allows multiple
loudspeakers to be looped from a single audio source. The
Loop output connector uses the same wiring scheme as the
Input connector (see “Audio Input (XLR 3-Pin Female)” on
this page). For applications that require multiple Amie-Sub,
connect the Loop output of the first loudspeaker to the Input
of the second loudspeaker and so forth.
NOTE: The Loop output connector is wired in
parallel to the Input connector and transmits
the unbuffered source signal even when the
loudspeaker is powered off.
Calculating Load Impedance for Looped Audio
Signals
To avoid distortion when looping multiple loudspeakers,
make sure the source device can drive the total load
impedance of the looped loudspeakers. In addition, the
source device must be capable of delivering approximately
20 dBV (10 V rms into 600
Ω ) to yield the maximum SPL
over the operating bandwidth of the loudspeakers.
To calculate the load impedance for the looped loudspeakers,
divide 10 k
Ω
(the input impedance for a single loudspeaker) by
the number of looped loudspeakers. For example, the load
impedance for 10 Amie-Sub is 1000
Ω
(10 k
Ω
/ 10). To drive
this number of looped loudspeakers, the source device
should have an output impedance of 100
Ω
or less. This same
rule applies when looping Amie-Sub with other Meyer Sound
self-powered loudspeakers.
NOTE: Most source devices are capable of
driving loads no less than 10 times their output
impedance.
TIP: Audio outputs from Meyer Sound’s
loudspeaker GALAXY Network Platform have
an output impedance of 50 ohms. Each output
can drive up to 20 Meyer Sound (10 k
Ω
)
loudspeakers without distortion.
CAUTION: Make sure that all cabling for
looped loudspeakers is wired correctly (Pin 1 to
Pin 1, Pin 2 to Pin 2, and so forth) to prevent
the polarity from being reversed. If one or more
loudspeakers in a system have reversed polarity,
frequency response and coverage will be significantly
degraded.
Figure 10: Amie-Sub Standard User Panel
!