PP output transformer for Williamson amplifier. Sowter’s interpretation of the original Williamson design using modern materials. Higher grade core material, improved copper and interwinding insulation for lower distortion and longer life. Highest grade low loss M6 Grain Oriented Silicon Steel core for minimal distortion. Fourteen interleaved winding sections to maximise bandwidth and ensure clean transient response. Two‑chamber bobbin to ensure full geometric balance. Low copper resistance to minimise losses and maximise loudspeaker damping. Four separate secondary windings for optimum matching to load without using tapped windings which can reduce HF response.