Fender Champion 600 akavalve Mods

Since the blog format is a bit awkward to navigate through, I thought I'd make up a table of contents for my Fender Champion 600 Mod posts. First are the essential safety posts and then the mods listed in order of difficulty with the easiest ones first.

Discharging the filter caps:

Part 1
Part 2



Tube Upgrade:

New preamp and power tubes


Input Voicing Mod

Part 1

Part 2
Frequency Response Measurement

Input Mod "Kit"
Cap values for different frequency response and
Mouser Electronics Parts Links.


Presence Plus Mod:

The Presence Plus Mod
The Presence Plus "Mod Kit"


Cathode Bypass Mod

Part 1
This one includes a couple charts for bypass cap values
and their frequency response for both
the stock circuit and the Frondelli mod.

Part 2
This is the installation of the mod.
It uses large cap values
but smaller ones detailed in Part 1
could easily be substituted.

Part 3
This shows the measured frequency response
with the four different settings of the
cathode bypass lift described in part 2.


Tone Stack and Fat Boost Mods

Tone Stack Test

Installation Details and Frequency Response Graph

Explanation of the Fat Boost Mod resistor values

Tone Stack Bypass Cap Values (same as 5E1 Champ)


The 12DW7 / ECC832 mod

Part 1

Part 2


Miscellaneous:

Animated GIF of the disassembly

A look inside the chassis

Stock Speaker response measurement

Comparison of the Champ 5E1 and 5F1 schematics

Stock Output Transformer Measurement


I'm pretty sure that's all of them.
I'll add new ones to this list as I post them.