Outputs
IMPEDANCE
OUTPUT |
Designed |
Actual |
Output Clipping |
|
for use with |
(Internal) |
Level |
Lo Imp Mic |
Any lo imp |
50 ohms |
- 20 dBV |
|
(19 to 600 ohms) |
|
(100 mV) |
|
mic c~rcuit |
|
|
HI Imp MIC |
Unbal 10 to 50 |
5 kilohms |
+4.5 dBV |
|
kilohms mic |
|
(1.7V) |
|
circuit |
|
|
Aux |
10 kilohm or |
2.2 kilohms |
+ 17 dBV |
|
greater unbal |
|
(7.1V) |
|
high-level |
|
|
|
circuits |
|
|
Mix Bus |
3.3 kilohms |
3.3 kflohms |
- 8 dBV |
|
|
|
(0.4V) |
Noise
Equivalent input noise: - 128 dBV (lo imp mic 150 ohms-300-20,000 Hz) at full gain
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)
Common-Mode Rejection
65 dB minimum with 100 mV input at 100 Hz
Control Interaction
Less than 1 dB with any control combination
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: 105-125volts, 50160 HZ, 5W M268E: 210-250 volts, 50160 HZ, 5Wt
Dc operation
A2688 Battery Power Supply (optional accessory): 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)
Dimensions
See Figure 1
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 installed 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 lowor 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. Both lowand high-impedance microphones can be used simultaneously. Crystal or ceramic microphones are not recommended. Impedance is selected by a slide switch above each input. The input receptacles are professional three-socket audio connectors.* See Figure 2 for lowand highimpedance connections to inputs. Note that some condenser 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 compensate for these "hot" microphones.
'Designed to mate with Cannon XL series, Switchcraft A3 (Q.G.) series or
equivalent connector.
2