• The gold standards for JFET matching are the Toshiba 2SK389 and Linear Systems LSK389 duals, whose Idss is matched ±1mA
  
  
• The JFET matching tolerance specified for any of Nelson's projects is the same, at ±1mA
  
  
• At ±1mA, the effect of tolerances in other components of your amplifier will have more effect and be more important than your JFET match. Adjusting for those variations is the purpose of the trim pots in your amplifier, and you can make those adjustments at operating temperature.
  
  
• There's no such thing as a perfect component, so don't stress. What matters is you feel you've spent your money wisely and you can sleep well at night.
  
  

About Our Matched JFETs

• Our matched JFETs are tested at 12V and 22'C. Current is read from a 100Ω resistor (dropping the voltage to 11V), with the source shorted to the gate. They were then sorted into 0.1mA bins. This results in a ±0.1mA match, which is an order of magnitude tighter than required. We guarantee the match is less than ±0.2mA, and most matches will be much tighter.

• N and P channel JFETs use different materials to achieve their opposite effect (pentavalent vs trivalent elements). They are not exact mirror images of each other and do not exhibit a perfectly linear mirrored response with relation to input. Different test conditions (voltage, temperature, test duration) will alter the match between N and P.