This is part 4 in the series of posts discussing the (audio) measurement pre-amplifier project. In part 1 I’ve covered the motivation for this project along with the circuit schematic and detailed circuit description. In part 2, I have gone through the board layout consideration and showed the assembled boards. In part 3, I have gone through measurement results of the assembled pre-amplifier board, as well as some circuit modifications to extend its performance. In this post, part 4, I will briefly show the assembled unit, along with slight discussion of external and power supply coupling into the signal.
As with many of my recent projects, I stuck to PCB’s for the front an rear panels of the pre-amplifier. The benefits are clear, its cheap, its very easy to design in the same software tools used for all of my circuit designs, and it offers electrical shielding due to the internal copper layers that are available to us. Unlike in my previous builds, this one is significantly larger, has very large holes, and even square cut-outs. Therefore, I wasn’t sure how well it will come out. To minimize the chance of an error I’ve printed the panels on a piece of paper and measured it in place before placing the orders. You don’t want to spend a few 10’s of $’s, and wait for a few weeks before you realize you’ve made a mistake 🙂 Continue reading “Audio Measurement Pre-Amplifier – Part 4 – Casing the Pre-Amplifier”