The national commercial radio multiplex Digital One experienced technical problems on Sunday morning which meant all stations fell silent.
It happened just before 10am, but some services resumed shortly afterwards. Absolute Radio, Amazing, Panjab, Planet Rock Premier and UCB didn't return till 11:40am.
The problem lied with multiplex owners Arqiva who experienced major technical problems.
BFBS, Classic FM and talkSPORT returned within an hour of the fault, which happened at 9:55am. National BBC stations are unaffected.
Arqiva managing director of radio Paul Eaton apologises for the break in transmission: "We apologise for the loss of Digital One and some other commercial and BBC DAB services on Sunday morning following the rare failure of an Uninterruptible Power Supply. The unit was only renewed very recently.
"This affected the IP distribution hub at Croydon, resulting in the loss of programme input to the transmitter network. We were able to deploy engineers quickly so that some services were restored within an hour, supported by a back-up system at Emley Moor. All DAB services were back to normal within two hours. An investigation has been launched to see what improvements can be made to the system and prevent recurrence."
