1、 ANSI/CTA Standard Standard Method of Measurement for Subwoofers ANSI/CTA-2010-B (Formerly ANSI/CEA-2010-B) November 2014 NOTICE Consumer Technology Association (CTA) Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings
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8、 license agreement. Requests to reproduce text, data, charts, figures or other material should be made to the Consumer Technology Association. (Formulated under the cognizance of the CTA R3 Audio Systems Committee.) Published by CONSUMER TECHNOLOGY ASSOCIATION 2015 Technology Phone 800-699-9277; Fax
9、 734-780-2046; Internet http:/; Email IEC Standards: International Electrotechnical Commission, IEC Central Office, 3, rue de Varemb P.O. Box 131, CH - 1211 Geneva 20 Switzerland; Phone +41 22 919 02 11; Fax +41 22 919 03 00; Internet http:/www.iec.ch 3.2 Informative References The following refere
10、nces contain provisions that, through reference in this text, constitute informative provisions of this standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the pos
11、sibility of applying the most recent edition of the standard indicated below. 3.2.1 Informative Reference List Gander, Mark, Ground Plane Acoustic Measurements of Loudspeaker Systems, Journal of the Audio Engineering Society, vol. 30, no. 10, p. 723 (1982). IEC 60268-1 ed2.0 (1985-01), Sound system
12、equipment. Part 1: General IEC 60268-1-am1 ed2.0 (1988-01), Amendment 1 - Sound system equipment. Part 1: General IEC 60268-1-am2 ed2.0 (1988-01), Amendment 2 - Sound system equipment. Part 1: General IEC 60268-2 ed2.0 (1987-06), Sound system equipment. Part 2: Explanation of general terms and calcu
13、lation methods IEC 60268-2-am1 ed2.0 (1991-05), Amendment 1 - Sound system equipment. Part 2: Explanation of general terms and calculation methods IEC 60268-5 ed3.1 Consol. with am1 (2007-09), Sound system equipment - Part 5: Loudspeakers2 ANSI/CEA-2010-B 3.2.2 Informative Reference Acquisition Audi
14、o Engineering Society Journal Articles: Audio Engineering Society, Inc.; 60 East 42nd Street, Room 2520, New York, New York 10165-2520, USA; Tel: +1 212 661 8528; Fax: +1 212 682 0477; Internet: http:/www.aes.org. IEC Standards: International Electrotechnical Commission, IEC Central Office, 3, rue d
15、e Varemb P.O. Box 131, CH - 1211 Geneva 20 Switzerland; Phone +41 22 919 02 11; Fax +41 22 919 03 00; Internet http:/www.iec.ch 3.3 Definitions Passive Subwoofer A subwoofer that does not include any active electronics Powered Subwoofer A subwoofer that includes an integrated power amplifier Sound P
16、ressure Level The level of the acoustic pressure radiated by the device under test (DUT), typically measured at a sufficiently great distance and mathematically converted to an equivalent value for a 1 m free field measurement distance Subwoofer A loudspeaker designed to reproduce all or a portion o
17、f audio signals below 160 Hz 3.4 Symbols and Abbreviations CF Crest Factor dB decibel DUT Device Under Test emf (electro-motive force) FFT Fast Fourier Transform HD+N Harmonic Distortion + Noise Hz hertz kHz kilohertz LF Low Frequency LFCS Low Frequency Calibration Source m meter MIV Maximum Input V
18、oltage Pa pascal RCF Room Correction Factor rms Root Mean Square SPL Sound Pressure Level Note: Throughout this standard all references to “dB SPL” refer to sound pressure level referenced to 20 Pa. SPLMUCOSound Pressure Level Maximum Usable Continuous Output THD+N Total Harmonic Distortion + Noise
19、V volt 3 3.5 Compliance Notation As used in this standard “shall” and “must” denote mandatory provisions of the standard. “Should” denotes a provision that is recommended but not mandatory. “May” denotes a feature whose presence does not preclude compliance, and implementation of which is optional.
20、“Optional” denotes items that may or may not be present in a compliant device. 4 Test Setup and Conditions CAUTION WEAR EAR PROTECTION! High sound levels can cause hearing damage with prolonged exposure. The operator is advised to wear appropriate protection such as ear plugs, preferably balanced at
21、tenuation devices which will still permit the operator to listen critically for distortion or other signs of distress in the device under test. 4.1 General Test Setup and Conditions All testing shall be conducted in an anechoic chamber or equivalent environment. During testing the DUT (device under
22、test) shall be operated as per manufacturers instructions. Complete systems shall be tested intact. Testing should be conducted at an ambient temperature of 22 C 5 C (71.6 F 9 F) and a relative humidity of 30 % to 80 %. If the conditions are different, they shall be noted at the time of the test. Bo
23、th of these items shall be recorded at the time of the tests. The ambient atmospheric pressure (in pascals) shall also be recorded. The rms (root mean square) mains voltage used to power the DUT shall be within 1 % of the rated value specified for use by the DUT (i.e. for a DUT that requires 120 V,
24、the mains voltage used shall be between 118.8 V and 121.2 V). All test equipment used during the tests shall operate within its linear operating range. For example, amplifiers shall be sufficiently powerful that they rarely clip or distort during any of the tests. If a crossover or filter network is
25、 specified by the manufacturer, it shall be installed according to the manufacturers instructions and utilized for all tests, including frequency response and maximum SPL tests. All test equipment shall be properly calibrated, and its calibration shall be documented. The frequency response measureme
26、nts shall be a transfer function type measurement employing a dual channel FFT (Fast Fourier Transform) or similar measurement apparatus. The measurement system shall have an amplitude resolution of at least 0.1 dB. See Appendix D for a list of all equipment needed to perform the tests in this stand
27、ard. 4.2 Verification of Frequency Response at DUT Input Terminals Measure the voltage at the DUT input terminals over the range 20 Hz to 20 kHz and confirm that it is within 0.5 dB from the specified voltage. If it deviates more than 0.5 dB the appropriate corrective action shall be taken, such as
28、the addition of equalization prior to the input terminals of the DUT. 4 ANSI/CEA-2010-B 4.3 Measurement Resolution and Calibration The measurement resolution shall be no wider than 1/20 octave. The specific bandwidth, resolution and test stimulus used should be documented. Calibration of the microph
29、one and data acquisition system, and of the post processing of the resulting data, shall be such that the system yields a measured sound level identical to that of a stable pure tone stepped or swept with an rms input voltage of 2.83 V (for passive systems only). 5 Frequency Response and Crossover C
30、ategory The frequency response of a subwoofer shall be measured in order to determine how high in frequency it may be used. This should be helpful in determining if a particular subwoofer can be recommended for use with a particular full-range loudspeaker system, or vise-versa. This assumes that a s
31、imilar low frequency limit is known for the full-range loudspeaker system. Four Crossover Categories are introduced to simplify and assist with this matching process. 5.1 Data Acquisition The loudspeaker (DUT) shall be loaded in a manner similar to that of normal operating conditions. If there are a
32、ny adjustable high pass or low pass filters on the DUT the high pass filters shall be set to the lowest frequency possible. The low pass filters shall be set to the highest frequency possible. If the roll-off rate of these filters is adjustable it shall be set to the slowest roll-off rate possible.
33、A transfer function measurement with a frequency resolution of at least 1/12 octave within the pass band limits of the DUT shall be made. The measurement shall cover the frequency range of 30 Hz (or lower) to 240 Hz (or higher). 5.2 Upper Frequency Limit The level of the transfer function measuremen
34、t shall be averaged over the frequency range from 60 Hz to 120 Hz. This level shall be the Average Level of the DUT. The frequency at which the transfer function has a level of no less than the Average Level minus 3 dB shall be the Upper Frequency Limit of the DUT. 5.3 Crossover Category Qualificati
35、on The DUT shall be qualified for each of four crossover categories W, X, Y, and Z. The frequency limit for each of these categories is shown in Table 1. Table 1: Upper frequency limit of Crossover Categories Crossover Category W X Y Z 80 Hz 100 Hz 120 Hz 150 Hz If the Upper Frequency Limit of the D
36、UT is higher than the frequency of a crossover category it qualifies for that crossover category. 5 As an example, a DUT with an Upper Frequency Limit of 130 Hz would qualify for crossover categories W, X, and Y. It would not qualify for crossover category Z. 5.4 Crossover Category Data Presentation
37、 The crossover categories for a subwoofer shall be reported in the following format: Crossover Categories: W, X, Y, and/or Z where W, X, Y, and Z represents each of the categories for which the DUT qualifies. The following statement shall also accompany the report. “Consult the manufacturers recomme
38、nded settings for optimizing the response of their products” For the example given in Section 5.3 the required reporting format would state the following. Crossover Categories: W X Y Consult the manufacturers recommended settings for optimizing the response of their products 6 ANSI/CEA-2010-B 6 Maxi
39、mum Usable Sound Pressure Level Continuous This test shall be conducted in a calibrated anechoic chamber, in a suitable ground plane environment, in a large calibrated room, or in a true free-field environment. 6.1 Input Signal The input signal shall be weighted pink noise with a 12 dB crest factor.
40、 Its power spectrum shall be as described in Table 2 when measured with one-third octave filters in accordance with IEC Publication 225. This signal may be generated by feeding a pink noise source through the filter processing shown in Figure 2. Table 2: Power spectrum of input signal Frequency (Hz)
41、 Relative level (dB) Tolerance (dB) Frequency (Hz) Relative level (dB) Tolerance (dB) 5 - 24.1 2.0 400 0 0.5 6.3 - 20.1 2.0 500 0 0.5 8 - 16.0 2.0 630 - 0.1 0.5 10 - 12.2 2.0 800 - 0.1 0.5 12.5 - 8.8 1.0 1,000 - 0.2 0.6 16 - 5.4 1.0 1,250 - 0.4 0.7 20 - 3.0 1.0 1,600 - 0.6 0.8 25 - 1.5 0.8 2,000 - 1
42、.0 1.0 32 - 0.6 0.6 2,500 - 1.5 1.0 40 - 0.3 0.5 3,150 - 2.3 1.0 50 - 0.1 0.5 4,000 - 3.5 1.0 63 0 0.5 5,000 - 4.9 1.0 80 0 0.5 6,300 - 6.8 1.0 100 0 0.5 8,000 - 9.1 1.0 125 0 0.5 10,000 - 11.8 1.0 160 0 0.5 12,500 - 14.9 1.5 200 0 0.5 16,000 - 18.2 2.0 250 0 0.5 20,000 - 21.8 3.0 315 0 0.5 7 Figure
43、 1: Spectral content of ANSI/CEA-2034 noise compared to IEC 60268 shaped noise Figure 2: Filter processing blocks for generating input signal Measure the crest factor (CF) of the input signal to the power amplifier and note the value. The crest factor shall be within the range 11 dB to 13 dB. If the
44、 rms voltage output of the power amplifier is operating close to or in excess of 1/8 of its maximum rms output voltage it may clip the output signal, resulting in a lower crest factor. Therefore it is important to measure the crest factor at the input to the DUT, and note its value, at each power le
45、vel used. It is important to ensure that the amplifier used for testing is capable of cleanly passing the input signal without misbehavior. Misbehavior can best be observed with an oscilloscope - look for unusual spiking, seemingly extended periods of clipping, or mutes. These can often be heard, if
46、 the sound of the DUT is audible. Typical crest factors at the input of the DUT should be between 9 dB and 13 dB. A loudspeaker is a high pass filter and its acceleration, and therefore its SPL, may generally have a crest factor a bit higher than the crest factor of the input signal. High Pass, 2nd
47、Order Butterworth, 20 Hz Pink Noise Low Pass, 1st Order, 4.40 kHz Low Pass, 1st Order, 8.00 kHz 8 ANSI/CEA-2010-B 6.2 Data Acquisition 6.2.1 Measurement Set-up The loudspeaker (DUT) shall be loaded in a manner similar to that of normal operating conditions. The test signal to be used shall be the in
48、put signal specified in Section 6.1. A transfer function measurement with a frequency resolution of at least 1/3 octave within the pass band limits of the DUT shall be used to measure the amplitude linearity of the output of the DUT. The reference for the transfer function measurement shall be eithe
49、r the output of the power amplifier directly driving the DUT or the output of the Level Control device used to adjust the amplitude of the test signal. The signal flow for the measurement shall be that shown in Figure 3. The output of the signal source shall be connected to the input of a level control device as a means to increase or decrease the amplitude of the signal during the test. The output of the level control shall be connec
