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Outputs
Dimensions
See Figure 1
Noise
Equivalent input noise:
-
128 dBV (lo imp mic 150
ohms-300-20,000 Hz) at full gain
OUTPUT
Lo Imp Mic
HI Imp MIC
Aux
Mix Bus
Equivalent input hum and noise:
-
125 dBV (lo
imp mic 150 ohms-20-20,000 Hz) at full gain
Output noise:
-90 dBV (master control down),
-65
dBV (master up) (input controls down,
300-20,000 HZ)
Output hum and noise:
-82 dBV (master down),
-60
dBV (master up) (input controls down,
20-20,000 HZ)
Output Clipping
Level
-
20 dBV
(100 mV)
+
4.5 dBV
(1.7V)
+
17 dBV
(7.1V)
- 8 dBV
(0.4V)
IMPEDANCE
Common-Mode Rejection
65 dB minimum with 100 mV input at 100 Hz
Designed
for use with
Any lo imp
(19 to 600 ohms)
mic c ~ r c u i t
Unbal 10 to 50
kilohms mic
circuit
10 kilohm or
greater unbal
high-level
circuits
3.3 kilohms
Control Interaction
Less than 1 dB with any control combination
Actual
(Internal)
50 ohms
5 kilohms
2.2 kilohms
3.3 kflohms
Phase
All microphone inputs and outputs and mix bus are
in phase; aux input is in phase with aux output, but
out of phase with pin 3 of mic connectors
Simplex Power
30 Vdc open circuit, 3.3 kilohms series resistance
Operating Voltage
Ac operation
M268:
105-125 volts, 50160 HZ, 5W
M268E: 210-250 volts, 50160 HZ, 5Wt
Dc operation
A2688 Battery Power Supply (optional ac-
cessory): 27 volts nominal at 12.2 mA typical
no-signal, 12.5 mA typical full output; 16.2 volts
minimum; approximately 40 hours battery life
with alkaline batteries, 4 hourslday duty cycle,
simplex off
External power:
30 Vdc, 12.6 mA no-signal,
12.8 mA full output
Temperature Range
Operating:
-
18O to 57OC (0° to 135OF)
Storage:
-
29O to 74OC ( - 20° to 165OF)
t
Can be rewired for 105-125 Vac operation (see Service section)
2
OVERALL DIMENSIONS
FIGURE 1
Weight
Net:
1.9 kg (4 Ib 2 oz)
Packaged: 2.8 kg (6 Ib 2 oz)
Certifications
M268 (only): Listed by Underwriters' Laboratories,
Inc. and listed by Canadian Standards Association
as Certified
CONTROLS AND CONNECTORS
I
WARNING
I
This apparatus must be earthed (grounded)!
The M268 power supply is energized when
the unit is connected to an ac source;
disconnect mains (power) plug from supply
when not in use.
Model M268E
Model M268E is supplied with a three-conductor
power-line cord without a plug. The plug should be in-
stalled by qualified service personnel. The brown lead
should be connected to the "live" or "hot" terminal of
the plug, and the blue lead to the neutral terminal. The
greenlyellow lead is the grounding conductor and
should be connected to the ground or earth terminal of
the plug.
Inputs
A maximum of four low- or high-impedance dynamic,
ribbon or condenser microphones can be connected to
receptacles marked MIC 1, MIC 2, MIC 3 and MIC 4. The
inputs are designed for low-impedance microphones
with 19 to 600 ohms impedance or high-impedance
microphones.
B o t h low- and high-impedance
microphones can be used simultaneously. Crystal or
ceramic microphones are not recommended. Im-
pedance is selected by a slide switch above each input.
The input receptacles are professional three-socket
audio connectors.* See Figure 2 for low- and high-
impedance connections to inputs. Note that some con-
denser microphones produce very high output signals
which may overload the inputs of many mixers; the
M268's feedback-type active gain controls virtually
eliminate the need for in-line attenuators to compen-
sate for these "hot" microphones.
' Designed to mate with Cannon XL series,
Switchcraft A3 (Q.G.) series or
equivalent connector.
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