AC-4 or AC4 may refer to:

Music

AC4 (band) AC4 is a Swedish hardcore punk band from Umeå, Sweden. Refused members Dennis Lyxzén and David Sandström had been talking about starting a new band for a long time. In the spring of 2008 Karl Backman had written songs for the new band and ...

, a Swedish hardcore punk band, or their eponymous album

Vehicles

Aircraft

Light Wing AC4 The Light Wing AC4 is a Swiss ultralight and light-sport aircraft, designed by Hans Gygax and produced by Light Wing AG of Stans. The aircraft was publicly introduced at the AERO Friedrichshafen show in 2013. It is supplied complete and read ...

, an aircraft *

Aviastroitel AC-4 Russia The Aviastroitel AC-4 Russia is a Russian mid-wing, single-seat glider designed by Vladimir Egorovich Fedorov and produced by Aircraft Cooperative Mechta, which became Aviastroitel, now Glider Air Craft. The aircraft is sometimes referred ...

, glider *

Comte AC-4 The Comte AC-4 Gentleman was a 1920s Swiss two-seat sport/ training aircraft produced by Flugzeugbau A. Comte. Design and development In 1927 the Swiss company Flugzeugbau A. Comte designed and built a prototype two-seat cabin monoplane designa ...

, a two-seat Swiss monoplane

Ships

USS Cyclops (AC-4) USS ''Cyclops'' (AC-4) was the second of four colliers built for the United States Navy several years before World War I. Named after the Cyclops, a race of giants from Greek mythology, she was the second U.S. Naval vessel to bear the nam ...

, a US Navy collier ship

Trains

Southern Pacific class AC-4 Southern Pacific Railroad's AC-4 (meaning Articulated Consolidation) class of steam locomotives was the first class of 4-8-8-2 cab forward locomotives. They were intended to improve on the railroad's MC (Mallet-Consolidation) class 2-8-8-2 locomo ...

, a class of steam locomotive

Tanks

AC4 tank The AC4 (Australian Cruiser Tank Mk. 4) was a cruiser tank designed in Australia in World War II as the intended successor to the AC3 Thunderbolt. Like its predecessors the AC4 was to have a one piece cast hull and turret. The AC4's most importa ...

a World War Two Australian cruiser tank.

Technology

* AC-4, an IEC

Utilization Category In electrical engineering utilization categories are defined by IEC standards and indicate the type of electrical load and duty cycle of the loads to ease selection of contactors and relays A relay Electromechanical relay schematic showing a c ...

Dolby AC-4 Dolby AC-4 is an audio compression technology developed by Dolby Laboratories. Dolby AC-4 bitstreams can contain audio channels and/or audio objects. Dolby AC-4 has been adopted by the DVB project and standardized by the ETSI. History Its developm ...

, Dolby Digital audio codec

Videogames

* '' Ace Combat 04: Shattered Skies'', a 2001 video game * ''

Armored Core 4 is a 2006 vehicular combat game developed by FromSoftware. It is the 12th installment and 4th main installment in the mecha-based ''Armored Core'' series, the game serves as a reboot for the franchise. It was released for the PlayStation 3 and ...

'', a 2006 video game * '' Assassin's Creed IV: Black Flag'', a 2013 video game