• Steven became a registered member 4 years ago

    • Robin replied 4 years ago

      Hi Steven, welcome the the TAN site.
      The schematic and layout posted in the Wiki section are better for building the kit. Note that the three circles marked 1M on the layout are actually 2 1 meg pots (Volume and Tone) and the other circle represents the input jack with a 1 meg resistor across the two outside terminals (assuming the input jack is a Switchcraft, the lugs can be different on other input jacks, like Radio Shack). The 1 meg resistor on the input jack shorts the jack to ground when no cord is plugged in and keeps the amp quiet. Not that the jack lifts the ground connection when a cord is plugged in and allows the input signal to flow through the 68k resistor to V1 (the pre-amp tube). The two 1 meg resistors in the Boost switch circuit are for pop suppression as they pre-load the bypass caps used to bias the pre-amp.

      Dave Hunter’s explanation (in the book and supplemental instructions) of how choose and connect the secondary leads from the OT works well. Although using the best matching secondary lead for a given primary tube(s) is optimal and easiest on the tube and OT, it is not super critical to be spot on. Fender has gotten away with a 100% impedance mismatch forever when using an additional load (speaker) in the AUX jack. It is unlikely that you would ever use the 32 ohm tap although 2 – 16 ohm speakers wired in series would be a 32 ohm load.