Can I replace the 6" speaker in the Fender Champ 600 with a 12" one or does it have to be the same size?

I was also considering a cabinet since it would be a lot easier to install, it says in the manual that the impedance is 4 ohms, whats a cab that would go well with it?
If you mean put a larger speaker than the stock 6" into the Champ you don't want to do it. Even if you had room you would have to remove and modify the baffle, which on an amp that small might destroy it. Weber makes a nice 6" replacement speaker (popular upgrade.) As far as an external cab the Champ is capable of running a 412 if desired. Just make sure to match impedance in either case.
get at least a 1x12" cab for it man... the 6" champ speaker is a joke. it sounds soooo damn boxy with it.
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