S-1
Control
Electronics
Unit
Operating Instructions
PUSH
CAUTION: Set voltage before applying power.
90-250 VAC
50-60 Hz
100mA MAX
The Meyer Sound S-1 is
a single-channel active
signal processor de-
signed for use with the
USM-1 Loudspeaker. It
occupies a single 1 3⁄4-
inch rack space.
+
+
+
+
90-105
105-125
Lift
AC Voltage Ranges
210
180
105
90
-
-
-
-
250
210
125
105
-
-
-
-
210-250
180-210
GND
Input
Input
Lo Sense
Hi Sense
Lo Out
AC Voltage
1/4
A
SloBlo
Hi Out
The functions of the S-1
are:
Input
•
•
Active crossover for
biamplification
PUSH
PUSH
SpeakerSense™
driver protection with
MultiSense™ function
Lo Channel
Amplifier
Hi Channel
–
+
–
+
•
•
True excursion limit-
ing to protect the
USM-1 drivers
Loudspeaker fre-
quency and phase
response alignment
Loudspeaker Cable
The S-1 operates at line level and is intended to be the
final component in the signal chain before the power
amplifier. Connections between the S-1 and the power
amplifier should be made according to the diagram
above.
The Sense connection must be made in order for the
driver protection circuitry to operate properly.
Connections
Note: The S-1 Sense inputs incorporate Meyer Sound’s
exclusive MultiSense™ function, which allows use of
multiple power amplifiers driven in parallel from a single
S-1 and having different voltage gains and/or power
ratings. The S-1 accommodates up to two power amplifi-
ers, and provides a separate Sense input for each. The
MultiSense circuit automatically tracks the power ampli-
fier with the greatest output swing to control the system
protection circuitry. These inputs are polarity-sensitive:
be certain that they are connected with correct polar-
ity, as indicated on the S-1 rear panel.
1. Signal inputs to the S-1 may be either balanced or
unbalanced. For best signal-to-noise ratio, use balanced
connections operating at +4 dBu nominal. The S-1 will
accept peak input levels up to +26 dBu balanced, or
+20 dBu unbalanced.
Note: The S-1 utilizes Meyer Sound’s exclusive ISO™
Input. Pins 1, 2 and 3 are transformer-isolated, and the
connector shell is connected to earth ground. The Input
GND/ Lift switch controls the connection between pin 1
and circuit common, which is tied to AC/chassis ground
through a 500 ohm resistance. If hum problems occur,
this switch may be used to control ground loops in the
system.
3. Signal outputs from the S-1 are active balanced at
+4 dBu nominal operating level, with pin 1 tied to earth/
chassis ground through a 500 ohm resistance. The maxi-
mum output level is +26 dBu balanced (+20 dBu unbal-
anced).
2. SpeakerSense™ connections are made from the
output of the power amplifier back to the S-1 Sense in-
puts. The Hi output of the power amplifier must be con-
nected to the Hi Sense input, and the Lo output of the
power amplifier to the Lo Sense input .
4. Connections between the power amplifier output and
the USM-1 should be made in accordance with the
USM-1 Operating Instructions. These connections
must be verified for correct polarity and correct channel
assignment (Hi to Hi, Lo to Lo).
Meyer Sound Laboratories, Inc.
2832 San Pablo Avenue
Berkeley, CA 94702
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S-1
Control
Electronics
Unit
Operating Instructions
To verify limiter operation in the field:
•
Supply an input to the S-1, preferably a sine-wave
oscillator. If you do not have an oscillator, use a
microphone and a mixer to produce a line level signal.
Set the input frequency according to this table:
Limiter Operation
•
•
Disconnect loudspeakers, leaving the amplifier and
the S-1 in their standard connection configuration.
Oscillator
200 Hz
Microphone
low growl
LF limiter
HF limiter
VHF limiter
If your amplifier requires a load, use resistive loads
sufficient to dissipate the full power of the amplifier.
5,000 Hz
16,000 Hz
loud whistle
loud hiss
•
•
Turn on both the S-1 and the amplifier.
•
Bring up the input until you see the corresponding
limit indicator come on. Since the indicator will light
only if the limiter actually operates, it provides a
positive indication that the limiter is functioning.
Set the VHF switch to VAR, the Lo Cut out, and the
Safe switch in.
The standard connection configuration for the S-1 Control
Electronics Unit uses a single two-channel amplifier as a
biamplifier, one channel for the lows and one for the
highs. In large systems where a number of S-1’s are
used, some may prefer to assign one or more amplifiers
only to the lows, and other amplifiers only to the highs. In
either case, the Lo and Hi amplifiers must have equal
voltage gain. If they do not, you may balance your sys-
tem using an oscillator and an RMS-reading voltmeter.
•
•
•
Input the oscillator to the S-1 and set its frequency to
1400 Hz ±5 Hz (Use a frequency counter if possible).
Balancing
Amplifier Gain
Set the S-1 Lo Cut switch out, the VHF switch to
CAL, and the Safe switch out.
Measuring with the voltmeter at the Hi amplifier out-
put, advance the S-1 Attn dB control to a convenient
reading (a few volts).
•
•
Connect the S-1 and amplifiers as you wish to use
them, leaving speakers disconnected.
•
Now measure at the Lo amplifier output, If the level is
different, adjust the input level control of the amplifier
whose output voltage is higher until the Hi and Lo
outputs are equal.
If an amplifier requires a load, use an 8-ohm resistor
sufficient to dissipate the full power of the amplifier.
Meyer Sound Laboratories, Inc.
2832 San Pablo Avenue
Berkeley, CA 94702
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S-1
Control
Electronics
Unit
Operating Instructions
Input Type1
Output Type
Balanced ISO-Input, 10k ohms, 5k ohms per leg
™
Specifications
Active push-pull, 600 ohms output impedance
Maximum Input Level
Balanced
+26 dBu
+20 dBu
Unbalanced
Maximum Output Level
Balanced
+26 dBu
+20 dBu
Unbalanced
Hum and Noise2
<-90 dBV
Dynamic Range3
108 dB
Sense Inputs
10k ohms true differential, opto-isolated
1400 Hz
Note 1:
ISO™ Input: Pins 1, 2 and 3
are transformer-isolated,
and shell is connected to
chassis/AC earth ground.
Electronic Crossover Frequency
Low Frequency Delay Type
Active all-pass
Note 2:
Driver Protection Circuitry
Low Frequency
“A”-weighted, unbalanced.
Note 3:
RMS limiter, 100 msec. integration time
LF excursion limiter (instantaneous)
High Frequency
RMS limiter, 100 msec. integration time
VHF peak limiter, 2 msec. on-time, 35 msec. release time
HF excursion limiter (instantaneous)
“A”-weighted noise floor to
maximum output.
Indicators
Sense/Amplifier Gain Detect; Hi and Lo
Green/Red LEDs
Red LEDs
RMS Limiter, Excursion Limiter; Hi, Lo and VHF
Safe
Green LED
Power Supply
Green/Red LED
Controls
Front Panel
Preset Panel
Input attenuator, AC power switch
Lo Cut switch, Safe switch, VHF var/cal switch
VHF control (3/4-turn screwdriver adjust)
Ground lift switch, AC range switches
Rear Panel
Connectors
Balanced Input/Output
Sense Inputs
3-pin XLR (A-3) female/male
Banana jacks (4 dual)
Power
90-125/180-250V AC, 50/60 Hz (rear-panel switchable)
19" W x 13⁄4" H x 73⁄4" D, standard rack mount
8 lbs (3.6 kg)
Physical Dimensions
Weight
© 1992 Meyer Sound
05.150.002.01A
Meyer Sound Laboratories, Inc.
2832 San Pablo Avenue
Berkeley, CA 94702
Download from Www.Somanuals.com. All Manuals Search And Download.
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