All Tube Circuit
The NT2H Lil' Night Train featured a three tube circuit.
The signal from the input jack was connected to V3a, the first half of a 12AX7 (ECC83) tube, the initial gain stage. The "Bright / Thick" switch then routed the signal from V3a either to the "Top Boost" tone control circuit ("Bright" position) or directly to V3b, a second gain stage ("Thick" position).
The preamplified signal then proceeded to V2, a second 12AX7 (ECC83). V2 served as a phase inverter or "splitter." The phase inverter circuit converted the single audio signal coming from the preamp and tone controls into two individual signals that are out of phase with each other. Each of these out of phase audio signals supplied one half of the output amplifier stage.
The signals from the phase inverter were directed to V1, a 12AU7 (ECC82) dual triode tube. While it would be more conventional to find a 12AU7 in the preamplifier circuitry of a guitar amplifier, Vox used it to power a 2 watt "push - pull" power amplifier stage in the NT2H. One triode of V3 powered the "push" side of the power amp, the other half of V3 powered the "pull" side.