circuit places a 12AX7 dual triode vacuum tube (or "valve") into the power stage, which is a tube configured to act as a small power amplifier. Too small to be used as an amplifier on its own, the output of this Valve Reactor circuit is fed to a solid state power amp that boosts the output signal. Electronics Though widely believed to be a class A amplifier, the AC30 is in fact class AB. It uses a quartet of cathode-biased EL-84 output tubes in push-pull configuration. The high bias condition is believed by some to be the source of the amplifier's famous immediate response and "jangly" high-end, though the lack of negative feedback, minimal preamp circuit, simple low loss tone stack, and the use of cathode biasing on the output stage play at least as large a role, if not larger. The Celestion "Blue" speakers that are integral to the AC30 also contribute much to the sound of the unit. The two 12" 15-watt speakers, often overdriven and at the brink of their power handling capability, provide a cutting mid-range speaker sound that is immediate and sharp and a distinction from the Marshall or Fender-style amplifier. References External links Vox's page on the AC30CC JMI's official page Valve amplifiers Instrument amplifiers