History

The impetus for the PINT was a combination of several things. First, I wasn't entirely happy with the MINT; it was only the second design I'd brought into production, and I knew I could do better. Second, forum member cetoole started publically working on a clone of the MINT. Third, there was a period of several months where the BUF634 (needed by the MINT) was unavailable. Finally, the amazing AD8397 came out; it's one of the few audiophile-quality op-amps that has enough output current that doing without a separate output buffer isn't a compromise. I'd had the PINT idea kicking around for a long time before this, but all of those things happening together finally got me moving. (MINT 2.0 was originally going to be designed around the TPA6120 headphone driver chip, which was the flavor o' the month before the AD8397 came out.)

The idea for the circuit design came from several places. First, it draws on the PIMETA design, which in turn draws on the PPA design. Like those two amps, the PINT uses a full-fledged "ground channel". (Read my virtual grounds article for a discussion of this topology's virtues.) Second, there was the general buzz on Headwize and Head-Fi about the AD8397. Using such a chip in place of the op-amp plus buffer combination is natural. Finally, I still keep in contact with Morsel, who has been talking about doing a "3-channel CMoy" for quite some time now. Between the confluence of events that gave me a need to replace the MINT and this soup of ideas, I began work on the PINT.

Most of the development process can be followed in this thread on Headwize. I initially called the amp "MINT 2.0", without thinking about what that acronym meant. When that truth dawned on me, I renamed it to the PINT.