Report of the meeting of the SC-05-05 Working Group on Grounding and EMC Practices of the SC-05 Subcommittee on Interconnections held in New York, NY, 2017-10-20
The meeting was convened at 16:30 by acting chairman B.C. Olson.
Attendees introduced themselves, 10 were present. A signup sheet was circulated.
The agenda was accepted after changing the date and location listed for the previous meeting from Berlin in 2017-05 to Rome in May of 2013. A report of the previous meeting was reviewed briefly but tabled due to its age.
Bruce Olson gave a historical review of changes in the committee chairmanship since he previously chaired it in 2011. When he became Standards Chair he needed to give up chairmanship of this group due to time constraints. The vice-chair, Jim Brown, was retiring and wasn't available to take the workload either. After some searching Bill Sachs agreed to become chairman but within weeks was brought down by health issues and ultimately passed away last year.
Bruce felt there was enough need for continuing work in this group that it is desirable to attempt to restart it.
AES-X152: Signal levels and impedances of analog audio interfaces
Scope: To develop a standard for signal levels and circuit impedances of audio system components and for the specification of these quantities in product data sheets [balanced, unbalanced]
Discussion: This topic will be tabled until there is a new permanent chair.
The current draft document is very old and should be reviewed by the new chair and the group via the reflector before spending time in discussion.
Liaisons:
There are changes coming in the IEC structure which may affect the topics discussed in this group.
New Projects:
A few years ago there was discussion of the challenges specifying the compatibility of loudspeakers and amplifiers. Two of the largest amplifier companies were represented among the people present in the meeting. The chair solicited their assistance in developing a standard addressing these challenges. He felt that much of the required material is already available in white papers on these manufacturers' web sites. Though there is some overlap with the activities of SC-04-03, the chair felt this was manageable.
New business:
Richard Cabot raised the issue that AES48 presents an incorrect impression of the proper way to handle grounding for high frequency signals. Although the drawing illustrates an acceptable grounding arrangement for audio frequencies, it will not work properly in the presence of high frequency noise generated inside the device. The chair felt that the issue could be addressed with a revision to one of the figures. Bill Whitlock volunteered to work with Richard Cabot to develop the appropriate changes.
Since AES48 is stabilized, making a change will require it to be unstabilized and assigned back to this group for changes to be made.
Bruce Olson asked if there were any volunteers to take over chairmanship of the group. None of the members present felt that they had the available time. Bruce reminded people that most of the work is done via electronic means between the meetings at conventions and that people can participate or even chair bi-annual convention meetings remotely. If anyone is interested in chairing the group they do not need to be able to physically attend the convention meetings.
Some additional discussion took place about appropriate changes to the group scope and selection of a name to match.
The next meeting will be scheduled in conjunction with the AES 144th Convention in Milan, Italy, 2018-05.
