Modding The Fender 600 Champion

Sometimes you find something you like but you learn it can be something much, much, more.

Enter the Fender Champion 600 guitar amplifier.

This is Fender's cheap little "reissue" of the original Fender Champion that was first issued in 1948 as a cheap student model using an 6" speaker driven by 3 watts of electrical power.

The current "reissue" looks outwardly the same but uses a modified circuit with a tone stack from the Fender Blackface Princeton amps. This tone stack robs a lot of power from the original Tweed circuit that the original Champion 600 featured.

I had recently joined a board that focuses on the Fender Telecaster guitar-fiddle. Lots of cool information can be found there including as I would find, modifications to the new Champion 600 amp.

The mods can be gleaned from here, I picked and choosed from the many posts contained here within: http://www.tdpri.com/forum/amp-central-station/95897-champion-600-upgrades.html

I learned from this thread that if you lifted a resister annotated on the breadboard as "R19" that it would essentially ground-out the Princeton tone stack (this deal that sets the equalization of the treble, middle, and bass to a set value and takes away A LOT of volume from the circuit). Grounding out this circuit allows the amp to sound like an original Tweed amplifier that the Champ 600 was originally designed. Clean American tones and when cranked would turn into this fuzzy American beast.

Reading this I knew it had to be done. I own a Fender '59 Bassman reissue amp and love the Tweed tone and knew I needed my new little amp to be able to achieve the same thing in it's own way.

Another mod I read about was lifting the "R7" resister that would give it a more "ragged" tone, I didn't know what that meant at the time, but it did sound really bad ass. I had some of the know-how so why not? (A note here, I still don't know what the "R7" serves in the circuit so I can't really define it or give it a name at this time).

I really wanted the amp to sound like the way I bought it, but reading into the modifications thread, I learned you could simply add a switch or switches that would ground out the resister/s or keep the circuits alive in the "on" position. Knowing a small thing or two about doing this, I know I could do this mod myself in a small amount of time.

One other mod was changing the grille cloth that came on the amp to a thinner material that allowed more sound through and didn't muffle the speaker. The cloth that comes on the amp as-is is a velvet like material that is very thick, many New Champ 600 owners call this "The Grille Blanket."

The following is a short photo essay on what I did on the amp.

First, the amp as it first was as I bought it (note the grille cloth, it was very nice looking I will admit):

After removing the backplate:

You can see the inner workings here, the tubes that came with the unit need to go too, more on that later.

Pulling the head, the part of the amp that contains the circuitry:

The shitty "Noname" 6V6 power tube had to go, here it is if'n you want to look at it:

Clearly it was made in Chiner in Dec Twenty-Ought-Seven, but it looks as crappy as it sounds, the 12AX7 that served as the pre-amp tube in the model was marked similarly, but in red print. It was pulled as well. the 6V6 power tube was replaced with a JJ 6V6 made in The Former Yugoslovia or sumshit like that. The 12AX7 was replaced with an extra Sovtech that I had on hand.

Here is what the baffle looks like after I pulled it from the amp cabinet:

You can see the "grille blanket" that enshrouded it, I pulled the staples and replaced it with this sexy diamond print thing that I got at Hobby Lobby:

JJ 6V6 in place as a test, the new grille cloth helped a lot with letting the sound out of the cab and speaker:

Next came the really heavy duty mods, lifting resisters "R19" and "R7." This was done here at this point by pulling on the resister bodies with a pair of needlenose and applying a soldering iron to one end of the resister:

You can see "R19" lifted to the upper left of the green wires and the "R7" lifted to the bottom right of the same.

The two resisters are at this point grounded-out and their respective circuits they serve are no longer part of the whole Champ 600 circuit.

I wired the ends of these to kill switches and these switches in turn went back to where the resisters used to hook into the breadboard, in this way I could go turn these two mods on and off.

Holes drilled into the chasis to for the kill switches that I bought at Radioshack for like $8.00 I think:

Here are the switches and the wires leading to the resisters and breadboard (I made sure the wires went to the same parts in relation to the switch so they'd both be "off" in the same position):

Finally, labeled the switches to illustrate what the do, this was done with my right hand and a Sharpie marker:

The top switch is the one that grounds the "R19" resister, labeled "Standard" and "Tweed" throwing this to "Tweed" grounds out the tone stack and makes the amp sound like a vintage Fender Tweed amplifier. Throwing this switch gives the amp about 1/3 more volume.

The bottom switch grounds out the "R7" resister and gives the amp a more ragged tone, it is somewhat more subtle but very cool. This is especially true with a Telecaster bridge pick-up setting.

Final photo, mods done and a victory brew on the bench:

Keep classy folks, keep playing American music.