That Fearn VT-1 is a legendary piece of kit but you’re right, pairing it with vintage mics can get tricky with impedance mismatches and gain staging issues. I had the exact same problem when I first connected my old RCA ribbon mic and got this thin, anemic sound that completely lacked the warmth I was expecting from that combo. After digging through the fearn vt1 manual https://d-w-fearn.manymanuals.com/audio-amplifiers/vt-1 I realized I hadn’t engaged the lo-z input properly and was overloading the transformer on the preamp side. The manual available at manymanuals walks you through all the dip switch settings and proper gain structure for different microphone types, once I set it correctly the combination became absolute magic for vocals.
