The pursuit of audiophile hi-fi is one upon which many superlatives and perhaps a little too much money are lavished. But it’s also a field in which the self-builder can produce their own equipment that is as good or often better than that which can be bought, so it provides plenty of interesting projects along the way. [Justin Scott]’s tube preamplifier is a great example, with its novel use of a pair of Nixie tubes to indicate the volume to which it has been set.
The audio side of the preamp comes courtesy of a four-tube kit from tubes 4 hi-fi, in which we notice another tube as power supply rectifier. The case is a beautifully made wooden affair with a professional front panel, but it’s the Nixies which make it a bit special. A high quality motorised potentiometer is used as a volume control, one of its multiple outputs is used as a simple potential divider to provide a voltage. This is read by an Arduino, which in turn drives the Nixies via a BCD-to-decimal decoder. The attention to detail in the whole project is at a very high level, and though he’s not shred any of its audio measurements with us, we’d expect it to sound as good as it looks.