Abstract: A wideband audio output transformer for use with a push-pull vacuum tube amplifier using a multifilar ribbon in which primary windings and secondary windings coexist. The multifilar ribbon is wound continuously around a common core side by side to form successive layers. The primary windings are connected in series by turning the multifilar ribbon after the layers of multifilar ribbon have been wound and connecting the trailing end of the multifilar ribbon to the beginning end of the multifilar ribbon. Two additional wires are added in parallel with wires of the primary windings in the multifilar ribbon to redistribute the effective capacitance throughout the windings. The winding scheme eliminates the signal imbalance of an output transformer with a balanced push-pull primary winding and an unbalanced secondary winding at high frequencies.

Abstract: An output transformer for use with a push-pull vacuum tube amplifier using a multifilar ribbon in which primary windings and secondary windings co-exist. The multifilar ribbon is wound continuously around a common core side-by-side to form successive layers. The primary windings are connected in series by turning the multifilar ribbon after the layers of multifilar ribbon have been wound and connecting the turned end of the multifilar ribbon to the beginning end of the multifilar ribbon. The winding scheme increases the coupling between the first half primary, the second half primary and the secondary without reducing performance at high frequencies. The secondary windings are connected in series or in parallel to obtain the proper turns ratio for the transformer. A method of interconnecting the secondary windings for different turns ratios is also provided.