SC-04-03 meeting, Paris, 2006-05

Report of the SC-04-03 Working Group on Loudspeaker Measurement and Modelling of the SC-04 Subcommittee on Acoustics held in Paris, France, 2006-05-20

The meeting was convened by J. Stewart called the meeting to order and introduced himself as new chairman, replacing D. Prince who was thanked for his work for the committee.

The meeting agenda was read and approved by no objection.

The report of the October 2005 meeting in New York was read and approved by no objection, but with clarification of the IEC document numbers and nature as described below in the "Liaisons" section.

Current Projects:

AES-1id-R: Plane-Wave Tubes: Design and Practice
J. Woodgate raised a number of editorial issues that Yonge explained could be corrected in the secretariat formating process. A. Voishvillo questioned the clause 1.2 identification of (rho(o).c times area) as Acoustical Impedance instead of (rho(o).c divided by area). The committee agreed to submit the draft for secretariat formatting. M. Yonge will communicate any questions arising from the secretariat format process on the reflector.

AES-5id-R: Loudspeaker modeling and measurement - Frequency and angular resolution for measuring, presenting and predicting loudspeaker polar data
No action was requested or required

AES2-R: Specification of loudspeaker components used in professional audio and sound reinforcement
Woodgate spelled out the original intent for the document; to identify base-line requirements for a loudspeaker (drive unit or system) specification sheet.

W. Ahnert requested that clause 6.6 refer to the AES-X83 draft in addition to AES-5id. C. Struck objected to editorial comments on p.10 and elsewhere. After some discussion it was agreed that the project was too far along to be held for ambiguous comments, but that change proposals with complete alternative text would be accepted for one more month (until July). Stewart will request that M. Buck incorporate these changes.

The committee otherwise agreed to submit the draft with all changes accepted for secretariat formatting. Yonge will communicate any questions arising from the secretariat format process on the reflector.

Development projects:

AES-X129: Loudspeaker Distortion Perception and Measurement
Stewart reported progress on the information document and task group meeting minutes. Two parts are on-line for review. Two more will be available this fall. Voishvillo offered to complete the perceptual model section. Stewart suggested to wait for M. Keyhle to become available. W. Klippel volunteered to shorten the loudspeaker model section. Stewart will contact Gilbert Soulodre for an update on the listening test section.

Voishvillo asked how the compilation of sections will be accomplished. Yonge pointed out that secretariat formatting would not change content. Stewart proposed to defer the topic until more sections are available.

Liaisons

IEC TC100
Klippel and Woodgate presented some detail on IEC activities. Two Publicly Available Specifications, IEC PAS 62458 and IEC PAS 62459 have been released. (Klippel had previously reported on these as standard drafts, IEC-100-991-NP and IEC-100-999-NP, and they are available for review in the SC-04-03 documents site.) IEC PAS 62458 is for large signal loudspeaker parameters and IEC PAS 62459 addresses the material properties of loudspeaker components. These documents will be reviewed by the IEC in 2009. It is probable that IEC PAS 62458 will then be incorporated into IEC 60268-5. Please offer any comments or suggestions regarding these documents through the reflector or at one of our standards meetings. While we have no voting rights within the IEC, our liason status does allow participation at the working group level.

The dynamic polarity amendment draft to IEC 60268-5 was briefly discussed. Woodgate asked that it be posted to the website. Klippel commented that the correct phase relationships were not taken into account.

ALMA International
D. Field will send an email regarding ALMA TM100 [formerly AES19-1992 (withdrawn 2003)] copyright permission to secretariat.

New Projects

Stewart asked if the study of the IEC documents or the CEA powered subwoofer standard constituted new projects. They do not. Yonge provided an overview of the process for creating a new project. Woodgate suggested that these potentially pertinent documents from other entities be posted as "information documents" and assess the response before taking further action. Stewart will provide a CEA contact name for Yonge to investigate their powered subwoofer standard further.

New Business

Steve Hutt announced intention to stand down as vice-chair

The next meeting will be held in conjunction with the 121st Convention, October 2006

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