Since it’s publication by Deane Jensen in 1980, the JE-990 opamp has gained near-legendary status as the heart of the John Hardy M1 microphone preamp. While the design is public domain, DIY versions have been few and elusive. Of these, the most well documented is Mnats PCB layout, avialable at Mnats’ website.

Mnats’ layout fits in the standard 2520 DOA footprint and uses the inductors originally specified by Jensen.