PIMETA v2 Headphone Amplifier
What is a PIMETA v2?
It’s a PPA-Inspired META42 successor: a portable headphone amplifier packing a lot of hi-fi punch. This is the second generation of this design. (See PIMETA v1)
Features of the PIMETA v2 design:
Small board size: 3.1" × 2.4" (79mm × 61mm)
Works with most FET-input op-amps in DIP-8 and SOIC-8 packages
National Semiconductor LMH6321 buffers on the outputs (SOIC-8 package)
PPA-like 3-channel topology keeps headphone return currents from disturbing the signal ground
Reverse power supply voltage protection
Supply voltage can be as low as 5 V, with suitable part selection
Near-silent power on and off
Adjustable class A biasing option for the op-amps
Output current can be run unlimited for least distortion, or limited to reduce risk of buffer damage under short-circuit conditions
Directly compatible with several different types of volume control, with easy adaptation to any type
Dense board layout packing a lot of features into a small space, with minimum trace lengths
4-layer design, with dedicated planes for V+, V- and ground, leaving the fourth layer free for wide signal traces
Patterned perfboard section — the scratchpad — designed with hardware hacking in mind!
Most parts on the board have footprints for both thru-hole and equivalent surface-mount parts, allowing uncommon freedom in part selection
More features than the previous generation, but still fits in the same popular Serpac H-65 enclosure
Where To Next?
Project FAQ — Newbies, start here!
Building the PIMETA Amplifier:
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Part List
Checklist
Part Selection Guide
Power Supply Matters
Step-by-Step Assembly Guide
Tweaks
Electronics Calculators