The M-1A ControlElectronics Unit
The UM-1C UltraMonitor operates as a
system with the M-1A Control Electron-
ics Unit (one per channel). Optimized for
the UM-1C and UPA-1C loudspeakers
and pre-aligned at the factory, the M-1A
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-1A is the final com-
ponent in the signal chain before the
amplifier.
SpeakerSense driver protection
circuitry protects the UM-1C loudspeaker
components from damage due to over-
heating under high power conditions.
This unique circuit continuously moni-
tors the power applied to the UM-1C
drivers, and individually limits the high-
frequency and low-frequency outputs
when the safe operating limits of the
drivers are exceeded. Until the onset of
overload, the SpeakerSense circuitry
has no effect on the signal.
Also provided is a switch-selectable
Safeguard function, which widens the
safety margin of the system and is in-
tended to be used when extended periods
of overload are anticipated. The Safe-
guard switch and other setup controls
are located behind a cover plate on the
M-1A front panel, providing a means of
securing the system installer’s presets.
To enhance the effectiveness of the
UltraMonitor in stage monitoring applica-
tions, the M-1A incorporates sliding filters
which band-limit the system response
under full-power conditions. This has the
effect of discriminating for vocal informa-
tion in the signal to increase clarity, and
is particularly useful when onstage levels
are high and leakage becomes a problem.
For this reason, it is recommended that
subwoofers be used with the system if it
must pass the full audio frequency range at
all times (as, for example, in keyboard
or drum monitors). The preferred choice
of subwoofer for the UltraMonitor is the
Meyer Sound USW-1.
UltraSeries™ M-1A
Power
Sense Limit
Safe
Adj
Lo Cut
Cal
VHF
Var
Safe
∞
20
10 843
2
1
0
Attn dB
5
6
+ -
Lo
Hi
VHF