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Twinings Tea Box 12AX7 Tube Preamp with External 5Y3 Power Supply
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In this build I used the Jensen copper, paper and oil caps for the input, output and inter-stage coupling and Solen Teflon for the feedback capacitor. The preamp is a two stage triode (12AX7s AWA-Australian) with global feedback and is the original Silicon Chip design with some modifications. They are bigger caps all round and no printed cct. brd. Construction of brds. was component-2-component wiring which means there is NO additional wire used on the brd. construction. At the brd. level this is better than point-2-point wiring. This cuts down on soldered connections/junctions and cct. length. All 99.999% pure silver wire with heat shrink insulation is used in the signal path to connect brds. to RCAs and Alps blue velvet pot etc. Medium gauge OFC hook-up wire brings power to the brds. Heavy bituminised Al foil lines the light timber case to provide a ground plain and RFI/EMI shielding. The remote PS employs a 5Y3 rec. tube (Australian made in this case) Hammond 370X power tranni 193B 12H choke.
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