Juancho wrote:
I've built a small battery powered step up amp in an aluminium case. What are your suggestions for best earthing practice?
1. Connect the case to signal negative
2. Connect the case to an earth post and connect back to the chassis earth on my tube preamp
Thanks!
Generally, best-practice is to eschew multiple grounds to avoid ground-loops. As you have not told us what you are stepping up I suggest the following:
If this is a MC-phono-cartridge step-up amp, then grounding through signal-negative is best.
If this is a line-level step-up amp, start with signal-negative, and if that creates issues, *ADD* a chassis-ground to the pre-amp.
And then, experiment between no signal-negative and with signal negative in this configuration.
Now: BEFORE you connect anything to anything, obtain a sensitive VOM and measure any potential, AC or DC, between the battery device and whatever you are connecting to it/it to. If it is anything more than a few millivolts, find out why before going further.