Today I assembled what I expect will be the final Ampisu prototype! Here’s what changed compared to the previous revision:

• Added mounting holes to secure the PCB to the aluminum enclosure

• Implemented a proper grounding scheme with a high-resistance path (10 MΩ ∥ 1 nF) from output ground to chassis ground

• Reworked the PCB around the output pin headers for better visibility and access

For low volumes, I prefer assembling prototypes myself rather than outsourcing — it’s usually faster and more cost-effective. That said, this board isn’t trivial: 201 SMD components (72 unique parts) adds up. Using my 3D-printed stencil printer, a Fritsch manual pick-and-place, and a Vapor Phase oven, it still took about three hours to complete a single board.

How do you handle prototype builds? Do you lean toward external assembly services, or do you prefer hands-on assembly?