FENDER: Tweed Princetons

I'll start with the Fender 5F2A Princeton, as this is generally considered to be "the one" for a lot of people.

Basically take a tweed Champ, and add the classic Fender one knob tone control, which has no insertion loss, and you're in business.  It's hard to go wrong with this formula, which is why it appears in so many amps.  

FENDER TWEED PRINCETON - 5F2A, SCHEMATIC & LAYOUT

• 12AX7, 6V6, 5Y3

• Classic Fender hi / lo input stage

• Standard Fender preamp component values / biasing 

• Preamp is cathode biased

• Volume 1M, Tone 1M

• 22n coupling caps

• 22k negative feedback from OT secondary to second triodes cathode 

• Simple heater wiring - one side grounded

FENDER PRINCETON - 5B2 SCHEMATIC

• Preamp is grid leak biased

• Simple heater wiring - one side grounded

• 6SL7, 6V6, 5Y3

• Jensen P8T

• Volume & tone 1M

• OT 7765

• PT 6500

FENDER PRINCETON - 5C2 SCHEMATIC

• 6SC7, 6V6, 5Y3

• 2 x triodes in preamp - the first feeds the second via a voltage divider to reduce gain

• Shared cathode resistor

• Volume & Tone 1M

• Volume & Tone control is sitting on the grid of the 6V6

• Simple heater wiring - one side grounded

FENDER PRINCETON - 5D2 SCHEMATIC

• 12AX7, 6V6, 5Y3

• Preamp grid leak biased

• Volume & tone 1M - 1meg resistor in series before the volume pot

• No negative feedback

• Simple heater wiring - one side grounded

FENDER PRINCETON - 5E2 SCHEMATIC

• 12AX7, 6V6, 5Y

• Classic Fender hi / lo input stage

• Preamp is cathode biased

• Volume 1M, tone 250k

• Slightly more complicated tone control - tone control sits on the first triode's plate, before the coupling cap

• Simple heater wiring - one side grounded

• Choke on power supply

• 22k negative feedback

FENDER PRINCETON - 5F2 SCHEMATIC

Almost identical to the 5E2 - no bypass cap on the first triode

• 12AX7, 6V6, 5Y3

• Classic Fender hi / lo input stage

• Preamp is cathode biased

• Volume 1M, tone 250k

• Slightly more complicated tone control - tone control sits on the first triode's plate, before the coupling cap

• Simple heater wiring - one side grounded

• Choke on power supply

• 22k negative feedback