From wikipedia:
"The
Fragile and
Close to the Edge tours had producer and engineer
Eddy Offord travelling with the band as their live sound mixer who operated a sound system developed by the
Clair Brothers. In addition, co-founder Roy Clair assisted with the operation of the system, and Geoff Haslam was hired as the recording engineer alongside assistant Mike Dunn to work on
Yessongs.
[1] As Offord was in charge of the band's sound on stage, he could not operate the recording equipment at the same time. This resulted in recordings that he was disappointed with as they were substandard. "
The ironic thing about the difficulties capturing live Yes w/ good fidelity is that their live shows always sounded amazing.