The S-1 Control
Electronics Unit
The USM-1 operates as a system with the
S-1 Control Electronics Unit (one per chan-
nel). A single-channel device operating at
line level, the S-1 is the final component in
the signal chain before the amplifier.
Optimized for the USM-1 loudspeaker
and pre-aligned at the factory, the S-1
contains frequency and phase response
alignment circuitry, and Meyer Sound’s
exclusive SpeakerSense
™
driver protection
circuitry, incorporating both peak and RMS
signal limiting as well as excursion protec-
tion.
SpeakerSense driver protection circuitry
protects the USM-1 loudspeaker compo-
nents from damage due to overheating or
excessive excursion under high power con-
ditions. This unique circuit continuously
monitors the power applied to the USM-1
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.
The S-1 SpeakerSense circuit incorpo-
rates Meyer Sound’s new MultiSense™
function, which allows the use of multiple
power amplifiers having different channel
gains and/or power ratings. The S-1 accom-
modates two stereo power amplifiers, and
provides separate Sense inputs for each. Its
MultiSense circuit, which implements an
analog OR condition, automatically tracks
the power amplifier with the greatest out-
put voltage swing to control the system
protection limiters.
To enhance the effectiveness of the
USM-1 in stage monitoring applications,
the S-1 incorporates sliding filters which
band-limit the system response under full-
power conditions. This has the effect of dis-
criminating for vocal information in the
signal to increase clarity.
Also provided is a switch-selectable Safe
function, which widens the safety margin of
the system and is intended to be used when
extended periods of overload are antici-
pated. The Safe switch and other setup con-
trols are located behind a cover plate on the
S-1 front panel, providing a means of se-
curing the system installer’s presets.
UltraSeries™ S-1
Power
Sense
Limit
Safe
Adj
Lo Cut
Cal
VHF
Var
Safe
∞
20
10
8
4
3
2
1
0
Attn dB
5
6
-
Lo
Hi
VHF
