2SK208-GR (matched)

This is a matched set of 2SK208-GR JFETs for use in phasers such as the Emerald (BOSS PH-1r) and Phase 90, pre-soldered to adapter boards for through-hole applications.

They are matched in sets of 4 according to their Vgs(10k) parameter, and are guaranteed to be within 0.05V of each other, although most sets are within 0.01V. The Vgs(10k) value will typically only be written on the first one to indicate the matching spec, but all four have been tested as part of our quality control process.

They can be ordered in increments of 2 for use in circuits such as the Phase 45. Each set of four is matched, so if you order 6, it will be one quad and one pair, not a matched set of six. Likewise, a quantity of 8 is two quads, not necessarily with the same spec.

2SK30A-GR replacement

The Toshiba 2SK30A JFET was used in many Japanese effect pedal circuits in the 1970s and 1980s. They were sub-classified based on their Idss specification, with yellow (Y) and green (GR) being the most common. Most notably, the 2SK30A-GR was used in the BOSS® PH-1 and PH-1r phasers. Toshiba no longer manufactures through-hole JFETs and the 2SK30A has been out of production for many years.

However, there’s a catch: while most USA manufacturers will only change the prefix to distinguish through-hole from surface-mount parts, e.g. 2N5457 and MMBF5457, Toshiba’s practice is to change the whole part number. And if you compare the datasheets, the 2SK208A shares the exact same specifications and sub-classifications as the 2SK30A. In practice, they also measure in the exact same ranges as the parts used in vintage units.

So in other words: the 2SK208-GR is not just a substitute for the 2SK30A-GR. It’s the same part manufactured with the same process, just in a different package.

Note: The drain (D) and source (S) pin labels on the adapter boards are reversed from the labels in the Toshiba datasheet. As with most JFETs, the source and drain are actually interchangeable and it does not matter which is which. The Toshiba datasheet does not specify this, but it can be confirmed using a Peak DCA75. However, cheap component testers may not show this correctly.