Report of the meeting of the SC-05-05 Working Group on Grounding and EMC Practices held online, 2021-10-06
The meeting was convened by chair Anthony Kuzub.
In attendance were Richard Cabot, Bruce Olson, Bill Whitlock, Rick Chinn, John Woodgate, Jim Meyer, Al Walker, David Robb, Paul Treleaven, Kenneth Fause, David Prince, Joan Amate, Marty Reiling, Jan Axelsson, Joel Brito.
The formal notice on patent policy was read.
The meeting agenda was accepted as written.
Minutes of previous meeting held online, 2021-05-14 were approved.
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 datasheet template that manufacturers could include in their manuals that explains 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.
This AES datasheet would allow users a quick glance of “How it works when you plug it in and turn it on”.
The chair reviewed the goals current data sheet parameters in draft form. 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 chair presented language aligned with other AES standards. With such a standard datasheet, 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.
In discussions afterward it was agreed that we should initiate a new project to produce a report that describes practical solutions when interconnecting combinations of balanced and unbalanced equipment. The technical level of the report would be one step above a magazine article and a couple steps below a typical AES standard.
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 contact of the shroud flange, and contact of the jack screws to chassis -with relationship to the to star point relationship. photos and Illustrations were stressed by industry representatives. Meetings throughout the year are booked on the group's reflector.
New Projects
A proposed project of a Balanced RCA standard was discussed. A patent exists for such a concept but was never implemented. Bill Whitlock and Bruce Olson will create a project proposal for this work. As it is a new connector the development would take place in SC-05-02.
Liaisons:
No activity to report.
New business:
None.
The next meeting will be scheduled in conjunction with the AES 152nd Convention, to be held online in May 2022.
