Hundreds of Eminem fans have blasted organisers of his concert at London's Wembley Stadium on Friday (11Jul14), alleging poor sound quality ruined the performance. The Stan hitmaker took the stage on Friday night after he was refused permission to perform in the city's Hyde Park because his lyrical content was deemed too offensive. While many fans applauded the hip-hop star for his hits-packed set, which included a guest appearance by Dr. Dre, others took to Twitter.com to take aim at the sound quality, and some reported seeing attendees leaving early in protest. One fan writes, "The sound is total rubbish to put it kindly at the #EminemWembley gig if it doesn't get better after the support I'll be super disappointed," while another remarks, "Not the best I've seen Eminem, but hey, Dre showed up! (also sound at Wembley Stadium is really Not Great)." Yet another disappointed guest told Britain's Daily Mirror newspaper, "I'm a big Eminem fan but this is the first time I'd seen him live. He was good but the set up wasn't great and the speakers were rubbish, for Wembley, you'd expect them to be better. We saw quite a few people leave because of the sound." A post on the venue's Twitter.com account during the performance said organisers were aware of the sound issues and had made adjustments, reading, "We are aware of some sound issues from earlier tonight & have monitored & adjusted it where necessary. We thank you for your patience." The rapper is due to perform at Wembley Stadium again on Saturday (12Jul14).