The agenda and the report of the previous meeting, held in Barcelona, 2005-05-29, were approved as written.
The main discussion was on the topic of self-noise measurement, which was the area of the round-robin test showing the greatest discrepancy among measuring labs. It was noted that the IEC standard contains an error, referring to a combination of weighting curve and detector type that is not practical. It was felt that this was probably due to a compilation error of the current standard. In order to help resolve the differences between labs in measuring microphone noise output, E. Brixen from DPA offered to produce a standard noise test source which could be evaluated by each of the labs participating in AES-X85 to see whether we can reach consensus on a testing method.
AES-X093: Recommendations for Revisions of IEC 61938 Clause 7
At the request of member H. Jahne, who was not present, the group discussed difficulties with phantom power. We are planning to once again urge IEC to revise IEC 61938 to keep up with advances in circuit topology. Jahne was particularly concerned about the imbalance in phantom power current drawn by microphones, which is permitted by the current standard but not by its predecessor DIN 45 596. The WG will continue to research modifications that can be recommended to the IEC standard.
The next meeting will be scheduled in conjunction with the AES 120th Convention in Paris, France, 2006-05