Jay Z fired back at critics of his Tidal music service on Sunday, claiming the site is “doing just fine” and that its subscriber base is growing. The rapper, who relaunched Tidal after purchasing its parent company Aspiro Group earlier this year for $56 million, urged critics to hold off on dismissing the service too soon. “The iTunes Store wasn’t built in a day,” he said. “It took Spotify nine years to be successful.” Jay Z added that 770,000 subscribers have already signed up for Tidal, which he relaunche to compete with platforms such as Pandora and Spotify.