SC-05-05 meeting, Online, 2021-05

Report of the meeting of the SC-05-05 Working Group on Grounding and EMC Practices held online, 2021-05-14

The meeting was convened by chair Anthony Kuzub.

In attendance were Richard Cabot, Richard Hess, David Andrews, Jim Meyer, Anthony Kuzub, Al Walker, Fred Morgenstern, David Prince, Paul Treleaven.

The formal notice on patent policy was read.

The meeting agenda was accepted as written.

Minutes of previous meeting held online, 2020-10-08 were approved.

Projects assigned to this group but not mentioned here had no action requested or required - see for details.

Open Projects:

AES-X152: AES standard on interconnections - Audio interconnection specifications
SCOPE: “To develop a standard for presenting signal levels and circuit impedances of audio system components and for the specification of these quantities in product data sheets” The goal / target / deliverable is a template that manufacturers could include in their manuals that explain the characteristics of the signals leaving devices and the characteristics of signals a device is capable of receiving. Having these parameters summarized in a consistent way will help users integrate equipment.

The chair reviewed the goals for and the issues the group faces in the project. A data sheet can contain many parameters. An AES datasheet would allow users a quick glance of “How it works when you plug it in and turn it on”. Discussion covered a wide range of topics including what qualifies as a "balanced" connection, impedances, levels, grounding and shielding both for radiation and susceptibility. The group created and tuned language to form a draft specification template for manufacturers to fill out. With such a standard datasheet for presenting standard measurable quantities or "Facts" about the transmitter and receiver design can be presented as being aligned with the AES's objective of maintaining interoperability. The draft document and working group maps are available in the groups repository.

We are requesting that makers of professional audio equipment using analog audio inputs or outputs apply the worksheet to a product and give feedback to the group.

AES-X249: AES standard on interconnections - Grounding and EMC practices - Shields of 25-way D-type connectors in balanced circuits
This standard specifies requirements for, and summarizes general considerations relative to, the shielding of DB25 type connectors used for multichannel connections of audio equipment, taking into account measures commonly necessary for the preservation of electromagnetic compatibility (EMC) at both audio and radio frequencies. This standard does not address issues of safety. The goal is to deliver a standard aligning with the efforts of AES54.

The group is working together to write an extension to AES48 as it relates to AES59 D-SUB 25 pin connectors for audio, solving the pin 2,5,8,11,16,19,22,25 problem. Discussion centered on the EMI shortcomings of common DB25 connectors, stemming from the fact that they were not originally designed for audio use. The group is focusing on best practices for shield plane to shroud to chassis to star point relationship. Illustrations are yet to be redrawn and text will be developed in work sessions through the year.

New Projects

No activity to report.


No activity to report.

New business:


The next meeting will be scheduled in conjunction with the AES 151st Convention, to be held online in October 2021.

AES - Audio Engineering Society