Where can I get the expanded manual for the Mustang GTX amplifier? You can view and download the manual right here! Related articles How to update the firmware on a Mustang GTX, GT or Rumble amplifier Fender® Guitar Amplifier Owner's Manuals Where can I get a copy of the Mustang GT Quick Start Guide? Fender Tone Master Pro Firmware and Pro Control App Updates Where can I get the manual for the Mustang LT amplifier?