Saturday, February 21, 2009

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.


opening the Fender Champion 600 for modding


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.







6 comments:

Jesús Omar said...

hi man, i have a question, can i change the 6v6 to 6L6 without rebiased? what could change in the sound?

thanks

akavalve said...

You could put a 6L6 in there without rebiasing and probably gain some clean headroom and output volume.

The problem is that a 6L6 requires more heater current than a 6V6 and you would probably overtax the power transformer and burn it out in fairly short order.

Dan said...

Hi,
I have a question about the Champ 600 output transformer. I read the post where you talk about measuring it, but I don't see one mentioning that you replaced the transformer. Are you still using the stock one in your Champ 600?

Thanks,
Dan

mzframes said...

what a great blog. Thanks. I've heard there's a mod to eliminate the hum. Any plan to show how? Thanks again.
Zig

stephen said...

Im looking into upgrading the 1/4 watt resistors to 1/2watt. Which ones need to be replaced?

Raoul DeJesus said...

I've been using a Sovtek 5881 WXT for months and so far there haven't been any problems with the power transformer. Nicer, fuller, more complex tone with more clean headroom then the stock china 6V6. I'm thinking about trying a KT-88 in there if the heater current is similar.