British Tape Recorders or BTR machines were reel-to-reel tape recorders initially made by EMI

EMI

The EMI Group, also known as EMI Music or simply EMI, is a multinational music company headquartered in London, United Kingdom. It is the fourth-largest business group and family of record labels in the recording industry and one of the "big four" record companies. EMI Group also has a major...

 in England after World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. They were the first magnetic tape recorders to be manufactured in Britain, and their design imitated that of the tape recorders used by the Germans during the war. Because these multi-track recorders were painted EMI green, they then became known as the "Green Machines".

The first model made was named the BTR/1. Later models included the BTR/2 and TR90 tape recorders.

The Otari company made a BTR-5 model recording machine but it stood for Broadcast Tape Recorder.

Mono and twin-track BTR reel-to-reel recording machines were used in the making of the first two Beatles albums. Mono and stereo BTR machines were used to mixdown the 4 and 8 track masters of later albums recorded on Telefunken, Studer and 3M multi-track machines.