Studio Technologies 742A Audio Mixer
The Model742A Audio Mixer is expressly designed for use in electronic-news-gathering(ENG) vehicles and small production truck applications. Many other fixed andmobile audio production, on-air, and utility applications can also besupported. Model 742A features include four mic/line inputs with +48 voltphantom power, four line inputs, two output buses, LED level metering, flexiblemonitoring, and AC and DC powering. The Model 742A was specifically designed asa dual-channel audio mixer, rather than as a typical stereo device. Thisapproach makes it excellent for “dual-path” on-air applications. As autility mixer the Model 742A can create two independent monaural signals,excellent for general signal monitoring, talent cueing, or intercom supportuses.
Key Features
- Fourmic/line and four line-only inputs
- Setuposcillator with dedicated output
- Studio-qualitycompressors
- Internalpower supply
- Flexiblemonitor section
- 10-segmentLED meters
- AC mains andDC powering
- +48 voltphantom power
- All operatorcontrols on front panel
- Singlerack-space mounting
TechnicalSpecifications
Frequency Response
20 Hz to 20kHz, -0.5 dB, mic/line in to main outs
Distortion (THD+N)
0.03 %,measured at 1 kHz, +4 dBu, mic/line in to main outs
S/N Ratio
74 dB,referenced to +4 dBu, mic/line in to main outs, 22 Hz to 22 kHz
Mic/Line Inputs
4
Input Sensitivity
Switchselectable for microphone or line-level signals; 44 dB line input”pad” implemented using sealed bifurcated contact telecom relays
Phantom Power
48 Vdc,nominal, meets IEC 61938 P48 standard
Operating Level Range
Mic inputposition: -76 to -8 dBu; line position: -32 to +28 dBu. Range specified to give+4 dBu on main outs, master level controls set to unity gain.
Type
Electronicallybalanced
Impedance
Mic position1.3 k ohms, line position 15 k ohms
Common Mode Rejection Ratio
74 dB @ 60Hz, 73 dB @ 40 kHz (typical), mic position, ref +4 dBu on main outs
Status LED
Dual-color,displays signal present and peak
Line Inputs
4
Operating Level Range
-14 to +28dBu. Range specified to give +4 dBu on main outs, master level controls set tounity gain.
Type
Electronicallybalanced
Impedance
24 k ohms,nominal
Common Mode Rejection Ratio
85 dB @ 60Hz, 85 dB @ 40 kHz (typical), ref +4 dBu on main outs
Status LED
Dual-color,displays signal present and peak
Compressors
2
Function
Controlsdynamic range of output buses 1 and 2
Type
Single-knee,VCA-controlled
Slope
5:1
Threshold
Configurable,choices are: 6 dB over nominal (+10 dBu on main output, factory default); 2 dBover nominal (+6 dBu on main out); disabled
Attack Time
2 ms
Release Time
100 ms
Status LEDs
2,compressor active
Main Outputs
2
Type
Electronicallybalanced, capacitor-coupled, intended to drive balanced or unbalanced loads of600 ohms or greater
Source Impedance
50 ohms,nominal
Nominal Level
+4 dBu
Maximum Level
+26 dBu into10 k ohms, +25 dBu into 600 ohms
Monitor Outputs
2
Signal Sources
Output buses1 and 2
Type
Electronicallybalanced, capacitor-coupled, intended to drive balanced or unbalanced loads of600 ohms or greater
Source Impedance
50 ohms,nominal
Nominal Level
Configurable,choice are: +6 dBu, with monitor level control @ 100%, mode configured for POSTlevel control; -10 dBu when configured for PRE -10; +4 dBu when configured forPRE +4
Maximum Level
+26 dBu into10 k ohms, +25 dBu into 600 ohms
Headphone Output
1
Signal Sources
Output buses1 and 2 (“post” monitor level controls)
Type
Stereo,configured to drive headphones through 100 ohm series resistors
Compatibility
Intended forconnection to headphones with impedance of 100 ohms or greater
Maximum Voltage
8 Vpp, 100ohm load
Reference Tone
Frequency and Wave Form
400 Hznominal, sine wave (technician can revise to 1 kHz)
Direct Output Level
+4 dBu,nominal, adjustable over -1/+3 dB range
Direct Output Type
Electronicallybalanced, capacitor-coupled, intended to drive balanced or unbalanced loads of600 ohms or greater
Direct Output Source Impedance
100 ohms,nominal
Meters
2
Function
Displayslevel of output buses 1 and 2
Type
10-segmentLED, modified VU ballistics
Connectors
Mic/Line and Line Inputs
3-pin femaleXLR
Main Outputs
3-pin maleXLR
ReferenceTone Direct Output, Monitor Outputs, Headphone Output: 1/4-inch 3-conductorphone jack
AC Mains Input
3-blade, IEC320 C14-compatible (mates with IEC 320 C13)
DC Input
4-pin maleXLR
AC Mains Requirement
100-240volts (-15/+10%), 50/60 Hz, 15 W maximum
DC Input
10-18 voltsDC, 1.0 A maximum @ 12 volts; 1.1 A maximum @ 10 volts; current draw when ACpresent is less than 100 uA
Dimensions (Overall)
19.0 incheswide (48.3 cm) x 1.72 inches high (8.9 cm) x 9.2 inches deep (23.4 cm)
Mounting
One space(1U) in a standard 19-inch rack
Weight
4.3 pounds(1.9 kg)
