SC-04-03 meeting, Online, 2021-05

Report of the meeting of the SC-04-03 Working Group on loudspeaker modeling and measurement of the SC-04 Subcommittee on Acoustics, held online, 2021-05-19.

The meeting was convened by chair S. Hutt.

Present were Richard Cabot, David Murphy, Steve Hutt, David Ranada, Daniele Ponteggia, Geoff Hill, Merlijn van Veen, Thomas Gmeiner, Joel Brito, David Robb, Neil Shaw, David Prince, Ian Robertson, Pietro Massini, Charlie Hughes, Roger Schwenke, Steve Thompson, Ahmed Gelby, Sheila Wark, David Andrews.

The formal notice on patent policy was read.

The agenda and the report of the previous meeting, held in online, 2020-10-05, were approved as written.

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

Open projects

AES2-R Review of AES2-2012: AES standard for acoustics - Methods of measuring and specifying the performance of loudspeakers for professional applications - Drive units
Scope: This Recommended Practice establishes a set of primary specifications to be followed by manufacturers in describing loudspeaker components used in professional audio and sound-reinforcement system design.

Status: Reaffirmed in 2017, target 2023

Discussion: No major activity since last meeting. When, restarting to consider x250 information on SPLmax measurements and applicability to raw transducers in free air. To consider test input levels for ratings, i.e. voltage, not power in watts.

AES-X168 Characterization of loudspeaker systems;
Scope: This document defines a set of characteristics of loudspeaker systems for inclusion in manufacturers’ specification documents, and identifies the relevant methods of measurement. It considers loudspeaker *systems* for professional applications. They may be combinations of active and passive sub-systems. It is intended for users and designers of loudspeaker system installations.

Status: Scope updated, writing has begun, first draft by David Murphy is posted to the repository.

Discussion: IEC documents relative to development AEX-x168 are published: 60268-21 - “Sound system equipment - Part 21: Acoustical (output-based) measurements and” and 60268-22 “Sound system equipment - Part 22: Electrical and mechanical measurements on transducers”. Geoff Hill and Rich Cabot will investigate receiving copies for committee review. Alternatively, Geoff as a member of the IEC committees can liasse information.

Sub-group development: David Murphy, as draft developer will work with Geoff Hill to review the IEC information and update the draft for Rich to format.

Target: Draft standard fall 2022

AES-X241 AES Standard for Acoustics - End of Line Testing for Production Loudspeaker Drivers
Scope: This standard specifies parameters and methods of measurement required for end-of-line quality control tests performed on loudspeaker drivers manufactured for automotive, consumer and professional applications. It includes requirements for mechanical setup. It does not consider measurements of loudspeaker systems or multi-driver arrangements.

Status: The group is gathering comments on a draft. The next stage is to consider tolerances.

Changing intent from Standard to Information Document. Changing target to 2022. Discussion: Pietro Massini has received additional end-of-line Characteristics and added to the spreadsheet. It was noted that defining criteria may not be ideal due to manufacturers having varying processes, however defining Best Practices could have good value for the industry at large. Therefore, it is prudent to change the intent from a Standard to an Information Document. Actions: members should Pietro to complete the specification template. Geoff Hill will work with original draft and update with methods of testing. Steve to follow up with Pietro and Geoff to move forward. We encourage participation from the committee.

AES-X250 AES Standard for Acoustics - Measuring maximum linear peak SPL using noise
Scope: This standard specifies a method for measuring the maximum linear peak SPL of a loudspeaker driver or system. It uses a mathematically derived test signal that effectively emulates the dynamic characteristics of music as a function of frequency as well as its spectral content. Status: Refining draft. The title will change, replacing “SPL” with “Sound Level”.

Discussion: Task group leaders Merlijn van Veen and Roger Schwenke are leading bi-weekly on-line meetings. Considerable progress has been made, carefully working through challenging definitions to align with external standards and references. The task group has worked diligently to attain consensus, now with few items to finalize. The draft will be circulated to SC04-03 for review and we anticipate general call for comments soon afterward. The project is still on track for late 2021.



New Projects

Measurement and characterization of headphone data provided by headphone manufacturers is not well aligned. SC-03-04 will review the current IEC work in TC100 / 60268-7 and consider initiating a project based on headphone measurement and characterization. - Actions, steve hutt to discuss further with Rich Cabot.

New Business

There was no 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