The era of record labels investing in their artists, giving them freedom to experiment and limited control over their content and marketing, ended with the late 1970s. Corporate artists and repertoire staff exerted an increasing amount of control over the creative process that had previously belonged to the artists, and established acts were pressured to create music with simpler harmony and song structures and fewer changes in meter. A number of symphonic pop bands, such as Supertramp, 10cc, the Alan Parsons Project and the Electric Light Orchestra, brought the orchestral-style arrangements into a context that emphasised pop singles while allowing for occasional instances of exploration. Jethro Tull, Gentle Giant and Pink Floyd opted for a harder sound in the style of arena rock.