This Vacuum Tube Preamplifier Features a Nixie Tube Display and Motorized Volume Knob
Justin Scott's PH-16 vacuum tube preamp includes a two-digit Nixie tube volume display and a motorized volume knob with remote control.
If you really care about the sound quality of your music, you aren’t going to be happy with the tinny sound of a cheap Bluetooth speaker or TV sound bar. Audiophiles can easily spend thousands of dollars on their home stereo systems. But, even among those enthusiasts, there is a lot of debate about which equipment is best. Do you want absolutely clean audio that reproduces the recording with perfect accuracy, or a system that adds a bit of warmth? Justin Scott was going for the latter, and constructed a vacuum tube preamplifier with a built-in Nixie tube display and motorized volume knob.
As far as the general public is concerned, vacuum tubes are obsolete technological components. But for guitarists and audiophiles looking for a particular kind of sound, vacuum tube amplifiers are ideal. Technically, the “warm” sound of a vacuum tube amp is the result of minor distortion from the tubes, but it is pleasant enough to be desirable. Scott's build started with a high-end PH-16 phone preamplifier kit from tubes4hifi.com. A complete PH-16 kit costs more than $700 after shipping, but the quality is quite good. Even so, the PH-16 is a “no frills” design without any controls other than a power switch. Scott's modifications dramatically improve on that design.
Scott designed the improved PH-16 enclosure in OnShape CAD software and created technical drawings to send to his father-in-law who does carpentry. A few weeks letter, he got back a beautiful cherry wood enclosure. Scott then added to the new components. Those include a two-digit Nixie tube volume display, a motorized volume knob with remote control, five selectable inputs, two selectable outputs, and a tone control to reduce bass when necessary. The motorized volume control was a prebuilt unit sourced from the eBay, and the Nixie tubes are controlled by an Arduino Nano board. The result is a fantastic vacuum tube preamplifier that looks better and is more convenient to use than the standard PH-16. It’s just one piece of Scott's stereo system, but it is an important one.