The MelChiOr 1337 and MeJLHior 1337 discrete opamp designs based on the Melchior 1731. They were designed with the goal of keeping the total cost below €2 for each amp, earning them the “frugal” designation. Both opamps feature a slightly more symmetrical transient response than the original and a more streamlined layout for perfboard. The designer has compiled perfboard layouts as well as some extremely useful instructions for tuning the output stages.

Resources:

• The desiger’s GroupDIY thread
• DIY Projects with discrete opamps
• Instructions and EULA (.txt file)