That third wire on the fender mustang speaker...

[maxnew40]

I have used a Mustang I for band rehearsal two weeks in a row now. It gets loud enough to play with our drummer and sounds pretty damn amazing. I think I will soon be buying a Mustang V.

 

Max

[Kid Klash]

The ground wire may have been nessasary to help prevent hum or the speaker basket from acting like an antenna. Since the chassis is so exposed its likely the amp needs all the help it can from picking up stray EMF. A coil in a speaker can act like an RF coil in a radio and carry that signal back into the circuit for reamplification. With the right test equipment, you can use an RF generatior and generate EMF noise. Manufacturers used to do those kinds of tests as part of quality control. Since they went with a minimal chassis, the unit was likely tested and found the ground wire was needed to make the amp quiet. There was a day when ectronic devices were tested to pass FCC and UL lisenceing and would require the circuits to pass a test so they would not interfere with broadcasting waves, nor receive broadcasted waves to be sold here in the US. Much of that has gone by the way side because many broadcasts are digital now and broadcast frequencies dont interfere with military or government bands like they used to. What the US may have required for low emmision /reception of RF was a full chassis where as with imports they were able to get away with a ground wire to the basket to act as an EMF blocker and pass inspection.

 

+1. I also suspect it's for EMI compliance. The modeling circuitry is digital, and who knows what the clock speed is (probably fast).

[MorganB]

Sounds right!