In case you're interested, you can indeed build a Pimeta v2 handheld amp with the following features:
- Serpac H65 enclosure
- Li-Ion cell pack 14.8V 0.75Ah with protection circuit
- Integrated modified Linkwitz Crossfeed circuit
- Integrated Bass Boost and Volume Boost circuit
- Integrated battery level control circuit with bi-color led
For some of you this may be a bit over-engineered, but to me it was a good exercise. The amp sounds brilliantly and qualitatively excellent, and the cells last for well over 10 hours. As a proof, see the following pics.
Lots of cables for the filters and boosters, but eventually it will fit. On the bottom see the bass/volume booster circuit as a piggi-back board to the R4 pins.
The 4 circuits all connected. The Linkwitz circuit required the big caps to be soldered horizontally, while one of the C4 Wima caps had to be moved to the scratchpad area.
On the bottom of the pic see the battery control circuit, which goes as a vertical piggi-back board onto the sratchpad area.
All fits precisely into the enclosure. The Li-Ion pack has been R&D'ed for this purpose - newest technology you can build these days.
Finally, the enclosure can be closed and the product is finished... happy listening!