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Playing now for a few weeks: a preamplifier built with transformers on nano-crystalline cores. It is a simple design, input transformer, amplification, step-down line transformer and autoformer for attenuation. Power supply is straight forward using a pair RGN1404 and C-L-C filtering. The R86, a directly heated triode, is used for amplification (alike 101D). The R86 is heated using Coleman regulators and partly biased using a 150C1 voltage regulator tube. Input transformer by Tamura, line transformer by Alexander Naydenov and autoformer by Tribute, the latter both on nano-crystalline cores. Perfect match and performers!