814 SE Amplifier: Custom Output Transformers

 Improving the 814 SE Amplifier

photo 3After more than a year listening to this fantastic amplifier, it was time to do the first significant improvement to it despite I resisted to modify it after so much work and effort put into the design and build. The evident upgrade was the output transformer. When frequency response was measured, it was evident to see that the HF response was lower than expected. This is the result of the transformer and its configuration in this circuit. The LL9202 is a better OT for higher impedances and in this circuit, it is used in the 6KΩ /8Ω mode.

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4-65A SE Amp: A2 grid current supply

Finished today the penultimate power supply of the 4-65a SE amplifier. This one is the A2 grid current one and doesn’t need a lot of filtering as the 46 driver gyrator will do most of that job. The DC stacked design of this amplifier will allow an independent loop of the A2 current between this supply and 4-65a grid-cathode.

Just only one more supply to go and I’m done!!!