My first headphone amp board wasn't the META42, but instead one for a CMoy type circuit. I did that board mainly because I was getting into building amps for others at that point and I was getting tired of building CMoys on perfboard. (You can see a picture of that amp board on my Notes on Audio Op-Amps page.) I never advertised that I had this board, since they were made for my use only, and I didn't think there would be many people who would want one.
Several of the MINT's major features first appeared in that CMoy amp board: it was about the same size as the MINT, it used the Panasonic EVJ pot, and it could be cut in half and mounted in a mint tin the same way as the MINT. However, my CMoy board had a few big flaws. One, it had a buffered virtual ground, but it wastefully used a resistor divider and a DIP-8 BUF634 for this. Two, it didn't segregate all of the tall components on one side of the board, so that the whole assembly took up more space in the case than a MINT, so you could only get one 9V battery into a mint tin with the board.
Once I started to run out of my CMoy boards, I decided to make a new board that fixed the above problems. I also decided to make a go at cramming a Jung multiloop amp into a similar amount of space. I succeeded in both efforts, with only one serious compromise: the op-amp isn't socketed in the MINT, so you can't tweak it like you can my original CMoy board or the META42. Since tweakability costs space, and the whole idea here is to save space, I had to let that feature of the original CMoy board go.
Thanks go out to all the people who helped with the META42, since that design process informed the MINT design process.
Thanks to David Mitra for being a guinea pig with one of the first-run prototype boards.
|Updated Sun Jan 18 2015 04:23 MST||Go back to Audiologica||Go to my home page|