The Arbiter company produced some notable guitar effects in the 1960s, like the Fuzz Face and had the UK franchise to distribute Fender and Teisco guitars. Dallas Musical Ltd aquired Arbiter Electronics in the late 1960s and formed Dallas Arbiter Ltd, with Ivor Arbiter as deputy chairman. Dallas Arbiter went on to produce the UK made Hayman range of guitars. They also distributed a ranged of Arbiter branded Japanese made electric guitars in the 1970s and 1980s, typically Gibson copies.

Ivor Arbiter left Dallas Arbiter five years after the merger, it was possibly after this that the company became Dallas Musical Industries (DMI). DMI continued at least until the 1980s.

Sources:

Grace's Guide to the best of British Engineering.

Sound City History