…breaking down an audio interface
Parts & Materials
Step 1. Step 2. Step. 3
Step 4. Step 5. Step. 6
This extremely rugged, portable, high quality, bus-powered USB interface features 2 switchable phono or line inputs, a microphone input, 2 line outputs, and pass thru outputs for the phono/line and mic.
- USB Input: bring power to the unit
- RCA: For audio input and output connectivity
- Audio Gain Knob: adjust volume of pass thru
– Motherboard
- Isolated ac/dc converter : An isolated power converter isolates the input from the output by electrically and physically separating the circuit into two sections preventing direct current flow between input and output, typically achieved by using a transformer.
- Programmable Logic Device: provides speed and power customization. Critical portions of design can run at high speed while remaining portions run at reduced speeds.
- High speed/ high temp 4 channel digital isolator: data transfer and signal isolation

Tools & Techniques
Screw Driver – used for removing screws connecting the side panels to the top and bottom pieces of the interface
Small Slip Joint Pliers – used in unscrewing the potentiometer nuts fastening the 1/4” jack inputs to the front and rear panels
Design Takeaways
One initial aspect of this design that I noticed right away, was that the input and output connections were inlaid, creating an overhang from the top and bottom slabs of metal. The top and bottom extend exactly the same length outward as the RCA connections. I believe this was deliberately done to prevent damaging the RCA and 1/4″ connections during use or travel. Without this design decision they would stick out making them much more susceptible to breaking off.
Another aspect of this design which I believe to be deliberate, is the shape. The short and wide design provides for a very stable object, limited the chances that is will fall or move while in use. This shape also gives the object a very low profile increasing its ability to fit in to smaller spaces or allow other tools to sit on top of it.