Ground Loops: How to Wire-up an Audio Amplifier for Zero Hum and Noise

Here is a short pdf that shows you how to wire-up a power amplifer and get zero noise – i.e. no hum.  For new builders,  this is often one of the most frustrating aspects to get right.  This simple guide should get you going in the right direction. The information will also be useful for anyone requiring a more detailed explanation of how hum arises in audio systems.

How to wire-up a Power Amplifier October 2017

For some practical examples of low noise amplifiers using these techniques, see the e-Amp, nx-Amplifier and sx-Amplifier on and for commercial examples of my designs visit

The picture below shows the internal wiring of one of the two nx-Amplifiers I have built with zero noise or hum problems. The power wiring is tightly bundled, and small signal wiring is kept well away from the transformer and other power wiring. On the PSU PCB, strict attention to the capacitor ‘T’ connection and ‘star’ ground return result in an exceptionally quiet amplifer.