Tecpro LS351

Talkback Loudspeaker Stations

The new Tecpro LS351 is a single circuit, desktop Loudspeaker Station featuring a carefully selected 80mm loudspeaker and a high quality, flush mounted electret microphone. Construction is based around a rigid aluminium extrusion with ABS side panels. The microphone, loudspeaker and associated controls are mounted on a machined top plate.

LS351 Series Talkback Loudspeaker Stations

Product Description

The LS351 Loudspeaker Station is designed to provide local monitoring of a single intercom circuit without the need to wear headphones. The built-in microphone allows full duplex (simultaneous talk and listen) conversations to take place. Feedback cancellation circuitry helps avoid acoustic howl-round when speaker and microphone are operating together. To further reduce feedback, a gooseneck microphone (which allows the operator to speak closer to the mic capsule) may be plugged in, disabling the internal microphone. If required, a headset may be plugged in, disabling both the internal microphone and speaker.

Pressing the 'Call' button causes 'Call Alert' lights on other Tecpro user stations to flash to attract the attention of operators who may have momentarily removed their beltpack and headset. The LS351 Loudspeaker Station can both detect and generate 'Remote Mic Kill' tone. If tone is detected and the microphone is active, it will be automatically switched off to help control the build up of unnecessary noise and chatter.

Pressing the 'Speaker Mute' button silences the loudspeaker output. To prevent important announcements accidentally going unheard when muted, the LS351 Loudspeaker Station will automatically restore audio levels to a pre-determined volume when an 'Override' control signal is generated elsewhere on the intercom circuit. The 'Override' loudspeaker volume is adjusted via a preset and can be set anywhere between zero and full volume.

Connection to the intercom system is via a pair of 3-pin XLR connectors which allow the LS351 to be daisy chained with other user stations. The LS351 derives power either directly from the 24V DC Tecpro line, or from an optional external 24V PSU. A green LED indicates power is present.

If monitoring of two independent intercom circuits is required, the LS352 should be considered.

Note: Care should be taken when using multiple LS300 Loudspeaker Stations in hands-free duplex mode. Although excellent acoustic feedback cancellation can be achieved at each station, system feedback can occur if several hands-free units are operated simultaneously. Using the microphone in push-to-talk mode will help reduce feedback. Alternatively, using a headset will eradicate the problem.

Versions Available:

LS311F Single circuit flushmount (screw terminal connections)
LS311T Single circuit table/surface mount (XLR 3 pin connections)
LS312F Mullti-circuit flushmount (screw terminal connections)
LS312T Multi-circuit table/surface mount (XLR 6 pin connections)
LS319FB Flushmount steel back box for LS311F and LS312F Detachable lid. Order LS311F separately.
LS331 Single circuit rackmount (XLR 3 pin connections)
LS332 Multi-circuit rackmount (XLR 6 pin connections)
Suffix F for flushmount
Suffix T for table/surface mount.
LS351 Suffix T for table/surface mount.
LS352 Suffix T for table/surface mount.
LS361 Suffix T for table/surface mount.
LS371 Suffix F for flushmount.
LS381 Single circuit rackmount
LS382 Dule circuit rackmount


  • Integral loudspeaker and electret microphone for simultaneous talk/listen
  • Feedback cancellation circuitry helps eliminate howl-round
  • Microphone On/Off button offers push-to-talk or latching characteristics
  • Inserting optional gooseneck microphone mutes internal mic
  • Plugging in optional headset mutes internal microphone and loudspeaker
  • Side-tone preset for headset
  • 20KHz and DC 'Call Alert' signalling send and receive
  • 24KHz 'Remote Mic Kill' send and receive
  • 28KHz 'Override' signal recognition for preset volume restoration
  • Compatible with legacy Tecpro products


Power requirements: 24 to 30 volts DC
Current consumption: Less than 175mA peak
External DC input: 24 to 30 volts DC
Current consumption: Less than 100mA peak with external PSU
Headphone output: 30 ohm to 4K ohm
Microphone input: 200 to 600 ohm dynamic microphones
Dimensions: 245mm (L) x 120mm (W) x 90mm (H)
Weight: 1150g