3-way Switched Feedback: My favorite mod, Normal / No Cathode Bypass Cap / Feedback - Adding Feedback increases clean headroom and civilizes the 5E3.

Add a Master Volume to make the 5E3 more pedal friendly and for low volume practice
6L6 & EL34 Power Tube Upgrade

Switched Bias: Fixed Bias / Cathode Bias so you can choose 'High and Tight' or 'Loose and Tubey'
High Voltage Tap Adjustable Fixed Bias: Get your fixed bias voltage from the power transformer high voltage secondary.

Cathode Bias Switch: Select three levels of cathode bias.

Voice a "Lead" channel: My second favorite mod, create some real difference between the Normal and Bright channels

Tube / Solid State Rectifier Switch: Harsh or Mellow rectification at the flip of a switch

Half Power Switch: Pentode / Triode switch to cut power tube output for lower volume

Add an FX Loop: Simple, passive FX Loop

Standby Switch 'Pop Reduction' and Current Surge Protection

Add a Variable Voltage Regulator (VVR3) Another low volume practice option

Bleeder Resistor Safely bleeds off high voltage DC after power down

Rectifier 'Backup' Diodes Cheap amplifier insurance

Simulate Tube Rectifier Voltage Drop and Sag Using a Solid State Rectifier and Sag Resistor

Channel Selector Switch Single Input Jack with Bright, Normal, or 'Jumpered' Bright & Normal channels

Input Jack Jumper Switch Jumper the input jacks without a jumper cable

Humbucker Switch Keep the 5E3 from 'farting out' when used with high output pickups

Add a simple Line Out Jack.

Eliminate Volume Interaction Remove some charm but simplify the 5E3's use
6.3v Filament Heater Artificial Center Tap Cut 60Hz heater hum
Elevate 6.3v Heater Center Tap Reduce heater hum.
LED Pilot Light: Simple LED circuit using 6.3v heater pow

5E3 MOD 

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