The MS301 master station has 3 channels, operated independently or linked in A+B and A+B+C modes. IFB is available on any channel. Front panel XLR allows for a headset, handset or goose-neck microphone. Powers up to 66 stations. 
 
Product Details
 
Three circuits rather than the usual two.
Each circuit can be intercom or IFB in any combination.
Circuits are linkable (A + B) or (A + B + C) with auto termination impedance adjustment.
Each circuit’s termination can be lifted via rear panel DIP switches. 
Independent level control of program audio output for each circuit with an LED VU meter for each. Mic switch on each circuit can be tapped for locking or held and released for momentary.
Internal power supply is linear (except for microprocessor functions) with 2.4A continuous output. 
Toroidal transformer with extensive monitoring and auto-control of overload and heat considerations.
Full duplex, hands-free operation, in moderately noisy environments. (with optional gooseneck mic.)
Paging output (balanced and isolated) on rear panel activated by front panel momentary button. 
Dry contacts on rear panel also closed by page button  Front panel 4-pin XLR may be used for gooseneck mic. or headset. 
Gooseneck or headset mic. may be dynamic or electret. Lighted front panel switch sets choice. 
Front panel green LED indicates presence of 24VDC across the three circuits.
Three front panel flashing red LEDs report trouble status of each circuit. Other circuits are not affected.
System resets when the problem is repaired.
While switching is all electronic, the audio paths remain analog providing comfortable long-term listening.
A front panel button initiates ‘Override’ which overrides front panel controls on LS2 and LS3 loudspeaker stations, restoring preset volume and status.