M-5 Control Electronics Unit
UltraSeries™ M-5
Power
Sense
Hi
Lo
Limit
Autosafe
∞
20
10 843
2
1
0
Attn dB
5
6
Safe
Safe
The MSL-5 loudspeaker operates as a
system with the M-5 Control Electronics
Unit (one per channel). Optimized for the
MSL-5 and aligned at the factory, the M-5
contains frequency and phase response
alignment circuitry, and Meyer Sound’s ex-
clusive SpeakerSense™ driver protection
circuitry, incorporating peak and RMS sig-
nal limiting as well as excursion protection.
A single-channel device operating at line
level, the M-5 is intended to be the final
component in the signal chain before the
power amplifier.
The M-5 SpeakerSense circuitry protects
the MSL-5 loudspeaker components from
damage due to overheating or excessive
excursion. This unique circuit continuously
monitors the power applied to the MSL-5
drivers, and limits the signal output when
the safe operating areas of the drivers are
exceeded. Until overload, the SpeakerSense
circuitry has no effect on the signal.
The M-5 SpeakerSense circuit incorpo-
rates Meyer Sound’s MultiSense™ func-
tion, which allows the unit to accommo-
date two amplifiers through separate Sense
inputs. The circuit, which implements an
analog OR condition, tracks the power
amplifier with the greatest output voltage
swing to control the system protection
limiters. This function prevents loss of
protection should one of the two power
amplifiers fail during high-level operation.
Also provided is a Safe/Autosafe switch
that affects the action of the protection lim-
iting circuitry. When the switch is in the
Safe position, the RMS limiters come on at
6 dB lower power levels, affording added
protection when heavy continuous power
demands are placed on the system. A green
LED indicator is provided on the M-5 front
panel which lights when the M-5 is in the
Safe mode. In the Autosafe position, the
M-5 monitors system power over time, and
automatically switches into Safe mode if
the power demands become too high.
Power Amplifier Requirements
Voltage Gain 16 dB, internally fixed
Power Output
0.5 sec. Burst at 4 Ohms 1800 watts
FTC Rating at 8 Ohms 1100 watts
Nominal (255 VAC) Operation With 4 ohm resistive load, reproduce three
specified burst waveforms 1, 2, 3 each continuously
for 1 hour without shutdown or limiting.
High (255 VAC) Mains Operation With 8 ohm resistive load, pass the FTC continu-
ous power test.
Low (200 VAC) Mains Operation With 4 ohm resistive load, reproduce a 400 msec
sine wave burst at 255 watts, 2.8 sec burst
interval, continuously for 1␣hour without shutdown
or limiting.
General Latch-up protection
Indicators for clipping, limiting, thermal overload
The MSL-5 requires a Meyer-approved
Type 3 power amplifier (for classification details, contact Meyer Sound) conforming
to the following specifications:
Notes:
1) Cycle consisting of 50
msec sine wave at 120V
peak and 450 msec sine
wave at 24 V peak.
2) Cycle consisting of 25
msec sine wave at 120 V
peak and 975 msec sine
wave at 41 V peak.
3) Cycle consisting of 400
msec sine wave at 120 V
peak and 2400 msec
interval at 0 V.
Sine wave frequency in all
cases is 1 kHz.