Used: Subsurface LD-18

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All-digital amplifier with automatic noise reduction of intermittent sounds, high and low filters, storage and graphing of sound levels at different locations on the pipe, bar graph and numeric display of sound loudness, USB connection, and back light.

  • LD-18 Amplifier showing filter settings, bar graph and numeric display of sound loudness, and minimum sound level detected
  • Automatic noise reduction capability for intermittent noises such as pedestrian footsteps, people talking, and passing vehicles.
  • 5 High Frequency filters, 3 Low Frequency filters (plus Low filter OFF), and 2 Notch filters (plus Notch filter OFF) to remove continuous interfering noises from A/C hum, motors, wind, etc.
  • Storage and graphical display of the leak‘s loudness at multiple locations along the pipe.

  • LD-18 Amplifier with Peak Display: The “Saved” data file showing 10 leak sound levels and graphical display. Leak is at the peak sound level in the center.


  • Combined Sensitivity and Amplification: 900 V/G or higher (at 400 Hz)
  • Low Filters: Off, 100 Hz, 200 Hz, 400 Hz
  • High Filters: 400 Hz, 600 Hz, 800 Hz, 1200 Hz, 2200 Hz
  • Notch Filters: Off, 50 Hz, 60 Hz
  • Maximum No. of Sound Levels Saved in File: 250 (by date and time)
  • Power: 4 C dry cell batteries
  • Battery Life (continuous use): 24 hours minimum
  • Weight: 35 ounces (including 4 C batteries)
  • Size: 6.4″ x 3.0″ x 5.7″ (163mm x 76mm x 145mm)
  • Weather Resistance: IP52 equivalent
  • Temperature Range (Working): Minus 4 F to Positive 130 F


Type: Piezo electric ceramic
Weather Resistance: IP67 equivalent (3 ft water depth for 30 minutes)

Standard Base: 3 – Pronged Plate(removable with nutdriver)

  • Amplifier with LCD Display, Controls, and USB Connection (to PC Computers)
  • Padded Case for Amplifier
  • 40 inches Belt (50 inches and 60 inches Optional)
  • Ground Microphone and Handswitch
  • Magnet Base and Nutdriver

Retails for $6,000
Sale for $4,900