The 2SK389 / LSK389 is a monolithic matched dual JFET on a single chip
Linear Systems replaces discontinued Toshiba 2SK389 with LSK389

Why use On-Chip Dual JFET instead of 2 single JFETS?

Save Cost
2SK389 / LSK389 removes significant cost for test screening time needed to match IDSS on 2 individual JFETS and offers ZERO yield loss.

Improve Performance
2SK389 / LSK389 On-Chip IDSS matching gives closest possible synchronous electrical performance and also offers better matched performance when the chip is subjected to temperature.

2SK389 / LSK389 Applications:
  End audio microphone, Audio Amplifier and audio effects box manufacturers
  Instrumentation-input stages of various instruments
  The acoustic sensor market –sonoboys / antisubmarine, military personnel and vehicle detectors, sonar makers. Radiation detectors.