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, 2021-10-07.
The meeting was convened by chair S. Hutt.
Present were Richard Cabot, Bruce Olson, John Woodgate, Steve Hutt, Merlijn vanVeen, Geoff Hill, Roger Schwenke, Daniele Ponteggia, David Murphy, Kommer Kleijn, David Robb, Neil Shaw, Richard Little, Joel Brito, Charlie Hughes, Joan Amate, Roberto Magalotti, Jan Axelsson, Brian Vessa, Lucio Bianchi, Massine, John Busenitz.
The formal notice on patent policy was read.
The agenda and the report of the previous meeting, held in online, 2021-05-19, were approved as written.
AES1id-R Review of AES-1id-2012 (r2017): AES Information Document for Acoustics - Plane-Wave Tubes - Design and Practice
Scope: To establish, expand, and improve the practice for the design and use of plane-wave tube measurement techniques, as recommended in section 2.2.1 of AES2-1984, "Recommended Practice Specification of Loudspeaker Components Used in Professional Audio and Sound Reinforcement."
Intent: Review, Target: 2022
Discussion: Need a volunteer to lead review of the current document.
Open questions include, what developments in measurement techniques are applicable to a revision?
David Murphy agreed to draft an informative annex on how to use impulse responses to adjust for minimum reflections.
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: With X250 (AES standard AES75) on maximum linear sound level imminent release, applicability to raw transducers in free air can be considered for AES2, perhaps using M-noise with band pass filtering. Should also begin review of terms and rating for input level in voltage, not power in watts though some definition of rated impedance should be considered. Test duration: ~100 hours may be appropriate for devices that would be installed in difficult to service systems (eg. stadiums) though, that might be more applicable to X168, loudspeaker systems.
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 and available for task group review in the repository: 60268-21 - “Sound system equipment - Part 21: Acoustical (outputbased) measurements” and 60268-22 “Sound system equipment - Part 22: Electrical and mechanical measurements on transducers”.
Drafts available for review: John Woodgate and David Murphy drafts are available for review. John Woodgate volunteered to revisit each draft to update with information from 60268 21-22.
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 2022/10.
Discussion: Need to update scope:
Proposed Scope: This standard information document 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 but may include sub-assemblies such as brackets.
It was suggested that an end-of-line test procedure for manufacturing loudspeaker drivers may also be of use for quality management for incoming QC, or ongoing QC, for example in the pro-audio segment.
We need volunteers to move this project forward.
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: Document is in formatting stage.
Discussion: Task group leaders Merlijn van Veen and Roger Schwenke have been leading bi-weekly on-line meetings over the last two years. The task group has worked diligently to attain consensus. M-Noise "free to use" patent license is defined and Standards Secretary Richard Cabot is working it through AES legal. Multiple use factors including 48kHz and 96kHz versions are defined. 44.1kHz sampling may be addressed depending on comments received before release. The document is in formatting stage.
Liaisons:
None.
New Projects
None.
New Business
There was no new business.
The next meeting will be scheduled in conjunction with the AES 152nd Convention, to be held online in May 2022.
