This article is from the Reggae FAQ, by Mike Pawka firstname.lastname@example.org with numerous contributions by others.
Look at the B-sides of Jamaican 45s beginning with rock steady, and
you'll notice many of them say "Version". This is "dub", a simple instrumental
remix of the A-side that may also include a few scraps of the vocals. The
singers are "dubbed out", but in most other respects the version is identical
to the A-side. Begun as a test for sound levels during the record-mastering
process, version later became vogue. The Jamaican public developed an avid
taste for version, and the scat-singing sound-system deejays took to recording
their master-of-ceremonies raps over the hit-backing rhythms.
"Reggae International", Davis and Simon
Chapter 8, X-Ray Music
The version was originally no more than an instrumental backing-track -
the B-side of a jamaican single with the vocal removed. But King Tubby helped
turn the simple version into a dazzling art form that became known as dub. In
the hands of such a master, dub at it's best could be as complex and rich in
musical interest as the original vocal. Tubby would strip the track down to
it's raw drum and bass and put it back together as something haunting and
strange, using fragments of the vocal as an instrument, in complex interplay
with the other instruments. He would build the tension with amplified cymbal
shots and thundering drum crashes, using reverb, echo and phasing in ways that
anticipated the experiments of contemporary dance music.
Geoff Parker Feb. 99
Liner Notes: The Sound of Channel One: King Tubby Connection
dub music was originally instrumentals of reggae tracks (also known as
"version"), usually put on the b-side of the single it was taken from, much
like rap and r&b singles of today. the name "dub" comes from the fact that
the vocals were "dubbed" out. as this style grew, many soundsystem dj's
would have mc's lay down scatting and rythmic poetry to the tracks (also
known as "toasting"), and many people credit dub with being one of the
foundations for early rap music.
king tubby, usually said to be the first known "dub producer", turned
this into an all around musical genre, using parts of the vocal tracks as
instruments, applying reverb, delay, echo, and phaser effects to them.
modern dub takes mostly from king tubby's style, but can also contain
elements of trance, house, raga-style drum 'n' bass, and hip hop. (i don't
really consider this to be true dub, but whatever.) dub eventually gave way
to dancehall reggae and has influenced jungle in a large part.