Brandes had booked a table, at a local Italian restaurant, for Jarrett to have dinner, but a mix-up by the waiting staff caused a delay in the meal being served and he was able to eat only a few mouthfuls before having to leave for the concert. Ultimately, Jarrett decided to play largely because the recording equipment was already set up. The concert took place at the late hour of 11:30 pm, following an earlier opera performance. The late time was the only one the administration would make available to Brandes for a jazz concert – the first at the Köln Opera House. The show was sold out, filled to capacity at over 1,400 people at a ticket price of 4 DM ($1.72). Despite the obstacles, Jarrett's performance was enthusiastically received by the audience and the recording was acclaimed by critics. It remains his most popular recording and continues to sell well decades after its release. The performance was recorded by ECM Records engineer Martin Wieland, using a pair of Neumann U 67 vacuum-tube powered condenser microphones and a Telefunken M-5 portable tape machine. The recording is in three parts: lasting about 26 minutes, 34 minutes and 7 minutes respectively. As it was originally programmed for vinyl LP, the second part was split into sections labelled "IIa" and "IIb". The third part, labelled "IIc", was actually the final piece, a separate encore. The Köln performance has since been the subject of an episode of a podcast by British journalist and broadcaster Tim Harford which looked at the role of obstacles and difficulties in fostering the creative process. A notable aspect of the concert was Jarrett's ability to produce very extensive improvised material over a vamp of one or two chords for prolonged periods of time. For instance, in Part I, he spends almost 12 minutes vamping over the chords Am7 (A minor 7) to G major, sometimes in a slow, rubato feel, and other times in a bluesy, gospel rock feel. For about the last 6 minutes of Part I, he vamps over an A major theme. Roughly the first 8 minutes of Part II A is a vamp over a D major groove with a repeated bass vamp in the left hand, and in Part IIb, Jarrett improvises over an F# minor vamp for about the first 6 minutes. "The Köln Concert" was released as a double-LP by ECM Records on November 30, 1975. It was later issued as a CD.