M-3A Control Electronics Unit
Connectors
Balanced Input/Output 3-pin XLR (A-3) female/male
Sense Inputs Banana jacks
Power 120/240V AC, 50/60 Hz (internally switchable)
Physical Dimensions 19" W x 1
3
⁄4" H x 7
3
⁄4" D, Standard rack mount
Weight 8 lbs. (3.6 kg)
The MSL-3A loudspeaker operates as a
system with the M-3A Control Electronics
Unit (one per channel). Optimized for the
MSL-3A and pre-aligned at the factory, the
M-3A contains frequency response and
phase response alignment circuitry, and
Meyer Sound’s exclusive SpeakerSense
™
driver protection circuitry, incorporating
both peak and RMS signal limiting.
A single-channel device operating at
line level, the M-3A is intended to be the
final component in the signal chain before
the power amplifier. Its factory-calibrated
SpeakerSense circuitry protects the MSL-
3A loudspeaker components from damage
due to overheating under high power
conditions. This unique circuit continu-
ously monitors the power applied to the
MSL-3A drivers, and individually limits the
high-frequency and low-frequency out-
puts when the safe operating limits of the
drivers are exceeded.
Until the onset of overload, the Speaker-
Sense circuitry has no effect on the signal.
Also provided is a switch-selectable Safe
function which widens the safety margin of
the system by decreasing the SpeakerSense
limiting threshold 6 dB, and is intended to
be used when extended periods of overload
are anticipated.
To enhance the effectiveness of the
MSL-3A in voice reinforcement applica-
tions, the M-3A incorporates filters which
band-limit the system response under full-
power conditions. This has the effect of
increasing intelligibility by discriminating
for vocal information in the signal. In
music reinforcement applications, the
Meyer Sound DS-2 Mid-Bass Loudspeaker
and 650-R2 Concert Subwoofer are recom-
mended to extend the system’s low-
frequency response and power bandwidth.
The M-3A contains logic
circuits within the sense
circuitry that monitors safe
operating conditions. In the
event of amplifier gain in
excess of 32dB, amplifier
failure or switched sense
lines, the M-3A outputs will be
muted to prevent speaker
damage.
UltraSeries™ M-3A Power
Sense Limit
Safe Lo CutHF Eq
Safe
∞
20
10 843
2
1
0
Attn dB
5
6
Lo
Hi
VHF
Cal
VHF
Var
Boost Cut