The sound had to be synchronised with the big screens, he said.
"We want a good, crisp sound throughout this events area while still meeting our noise model requirements."
The plan to do the sound checks from 9am to 5pm on the Thursday was changed because of the Pacific Islands Forum leaders' meeting.
The forum runs from September 6 to September 9 and will use the Cloud on Queens Wharf, as well as the SkyCity Convention Centre and Viaduct Events Centre.
To avoid problems, sound checks affecting Quay St and the Viaduct will not start until 3.30pm on the Thursday and will run until to 8.30pm.
Sound checks for the band playing at the Queens Wharf area will be from 3.30pm to 9.30pm.
Acoustic consultant John Styles said a range of public events during the Cup could cause adverse noise effects for CBD hotels, offices and apartments.
The level of crowd noise may be greater than that of the PA systems.
Mr Styles said an effective communication plan was needed to give warning to people of the noise from the opening and closing ceremonies.
COMPROMISE
* 500 delegates will be in town for the Pacific Islands Forum from September 6-9.
* Sound check times have been changed because of the meeting.
* 9am to 5pm on September 8 were the original times.
* Now they will not start until 3.30pm, and will run until 8.30pm.