First Post: 5F1/5F2A-inspired Amp Head

This blog is a way for me to document my projects, as well as to share my thoughts with whoever may stumble upon these posts.

5F1/5F2A-inspired amp internal wiring.

My first amp head build:

• 3 way V1A Cathode Bypass Capacitor switch between 1uF, none, and 25uF. 
• 3 way switchable tone options: 5F2A tone knob, tone bypass (5F1 spec), bright caps.
• Bright caps switchable between 100pF and 470pF.
• 3 way switchable NFB: fixed 22k, none, 50k linear pot.
• ClassicTone 40-18030 5W Output Transformer.
• ClassicTone 40-18085 Upright Power Transformer.
• 22uF, 16uF, 8uF filtering.
• Metal film resistors throughout.

B+ measurements: 380V, 331V, 281V at 3 Filter Capacitors. This is at the upper edge of expected values for the Tweed Champ circuit. The 630V CT @ 100mA secondary on the 40-18085 Power Transformer was used.

The amp doesn't quite get to 5F2A specs, since it has 1 less filter cap ala the 5F1 circuit.

YouTube videos of switchable options: