Report of the meeting of the SC-05-05 Working Group on Grounding and EMC Practices held online, 2022-05-05
The meeting was convened by chair Anthony Kuzub.
In attendance were Anthony Kuzub, Richard Cabot, Bruce Olsen, Paul Trevene, Richard Hess, Kenneth Fause, John Woodgate, Al Walker, Arrie, Fred Mogenstern, Jim Meyer.
The formal notice on patent policy was read.
The meeting agenda was accepted as written.
Minutes of previous meeting held online, 2021-10-06 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.
Drafts of the documents are posted in the repository. The scope of the project has shifted. It now includes interactions of the driver, the interconnecting cable, and the receiver. The focus is on end-to-end balanced interconnections.
A definition section has been started. Common terms that are not in other AES standards need to be included. "Transmission link" and the use of RF terms in general is not appropriate.
The document should describe the function and specification of senders and receivers, focusing on the actual results and desired results of connectivity.
Group members created some symbols illustrating what various interface types look like. Theoretical models are useful for this. The current illustrations are placeholders for conversations about their interactions.
Compatibility charts have been created. Should we include recommendations: Excellent, Good, Fair, Poor, and Not Recommended?
Should we include a section on the impact of bad practices?
The group discussed whether we should include a conformity declaration. What are manufactures going to present?
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 designated shield contact of the shell of the equipment connector(s) shall have a direct-current connection to the shielding enclosure via the lowest impedance path possible. In the case of the D-type connector, it is strongly recommended that this connection be to the outside of the chassis or shielding enclosure. See Figure (Proposed). When a shielded connector is used, it should be of a type that provides a connection having the lowest practical impedance at radio frequencies between its shell and the shell of a mating connector.
Good engineering practice encourages implementers to locate the star point, the connectors, the jack screws, the shroud flange and the signal circuitry as close as possible to each other in order to gain the greatest benefit from the cable shielding. The purpose of the shield plane is to direct the multi channel cable shields towards the shield enclosure, away from the system circuit using contact of the shroud flange and the jack screws bonded to the shielding enclosure.
New Projects
None.
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.
