Ultra-low noise discrete microphone/line preamplifier with hand-selected 12AX7 tube for ultra-musical sound Mic input stage based on discrete, conjugate transistor pair circuitry Ultra-wide ...

[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 ...