SV 977D User Manual - Appendixes
Normal operating mode
SV 977D in configuration with the SV 12L microphone preamplifier and MK 255 microphone with following
settings: High or Low measurement range (path: <Menu> / Measurement / Range – see Chapter
4.6),
switched on Microphone compensation, selected Free Field compensation and switched off Windscreen
compensation (path: <Menu> / Measurement / Compensation – see Chapter 4.5).
Conformance testing
This chapter contains the information needed to conduct conformance testing according to the specified
standards.
Mounting for acoustical tests The microphone must be mounted on the preamplifier.
Electrical substitute for the microphone To obtain a BNC type electrical input, the microphone
must be replaced by an electrical equivalent impedance
ST 02 with the serial capacitance 18 pF ± 10%.
Note: The ST 02 impedance has equivalent electrical impedance to the microphone MK 255.
However, some other features of these two devices are different! One important difference is
microphone sensitivity fluctuation versus temperature. To ensure better accuracy of SV 977D the
microphone temperature drift is digitally compensated. The correction factor is equal to 0.01 dB/K re
23ºC This correction is controlled by switching the Microphone compensation in the Compensation
settings screen (path: <Menu> / Measurement / Compensation).
Note: For electrical environmental conformance tests with the ST02 impedance, the Microphone
compensation must be switched off.
Note: For acoustic conformance tests (with the microphone installed), the Microphone
compensation must be switched on.
Note: For acoustic conformance tests with the installed SA 22 windscreen, the Windscreen
compensation must be switched on.
Periodical test upper frequency 8 kHz
Weighting filters (see part C.3)
• Z meeting requirements of IEC 61672-1:2013 for the Class 1 “Z“ filters
• A meeting requirements of IEC 651 and IEC 61672-1:2013 Class 1 “A” filters
• B meeting requirements of IEC 651 and IEC 61672-1:2013 for Class 1 “B” filters
• C meeting requirements of IEC 651 and IEC 61672-1:2013 for Class 1 “C” filters
• D meeting requirements of BS 5721:1979
• U meeting requirements of IEC 61012:1990 for Class 1 “U” filters,
• AU meeting requirements of IEC 61012:1990 for Class 1 “AU” filters,
• D meeting requirements of BS 5721:1979,
• HP high-pass filter,
• LF low frequency (20-200 Hz) real-time band pass filter.
Linear operating ranges
Two measurement ranges are available: High (primary) and Low.
The starting point at which tests of level linearity shall begin is 94.0 dB for the frequencies specifies below. For
the Low measurement range and A weighting linearity test at 31.5 Hz, the starting point is 74 dB.
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