Originally posted by mlynn02
so each speaker should be 8 ohm, because the line out from the amp and the ext. out are each 4 ohm?
did i understand that right?
Originally posted by John Phillips
You want two 8-ohm speakers for the amp, wired in parallel for 4 ohms and connected to the Main jack.
You can then run any 4, 8 or 16-ohm cabinet from the Ext jack, at the same time.
All those Fender amps are designed to handle a low mismatch down to half the matching impedance with no problem at all.
The only thing not to do is run a 16-ohm cab as the only load (ie with the internal speakers disconnected). Even then you probably won't kill it, but it's a bad idea.
One major reason old Fenders are so reliable is because Leo understood that musicians didn't pay too much attention to correct matching, so he did it for them by making the internal speakers (how the amp was normally expected to be used) the right load, and then making sure the amp would handle any normal mismatch too. There's even a shorting switch in the Main jack so if you forget to plug the speakers back in, the amp doesn't run with no load.