This is one of the very few Yesshows where Jon strains his voice, and in places is not quite reaching the notes. It’s most noticeable in 'The Gates Of Delirium' where he is so distracted by his voice problems that he misses a cue in the ‘Soon’ section.
Also of note is that Patrick Moraz plays ‘Happy Birthday’ during his piano solo and the encore is 'Starship Trooper' – one of only four recordings known to exist of Yes performing it in the Moraz era!
I have a live tape from the 7/22, 1975 Phila. Spectrum show. That night they did not play the Awaken excerpt or Sweet Dreams and Jon must have hada somewhat shot voice because during one of the songs he comments, "I seem to be accompanied by a frog tonight."