ANSI CTA-2006-B-2009 Testing & Measurement Methods for Mobile Audio Amplifiers (Formerly ANSI CEA-2006-B).pdf

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1、 ANSI/CTA Standard Testing separate single and multi-channel amplifiers, integrated amplifiers and bandwidth-limited amplifiers that are connected to and rely solely on the vehicles primary electrical system for power input and have output power ratings of greater than 5 watts when measured in accor

2、dance with CEA-2006-B. See CEA-490-A for testing and measurement methods for those audio amplifiers that are not designed for in-vehicle applications. 2 References 2.1 Normative References The following standards contain provisions that, through reference in this text, constitute normative provision

3、s of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards listed in Section 2.1.1. 2.1.

4、1 Normative Reference List CEA-490-A, Testing and Measurement Methods for Audio Amplifiers, December 2004 IEC 60651, Sound Level Meters, October 2001 2.1.2 Normative Reference Acquisition CEA, IEC Standards: Global Engineering Documents, World Headquarters, 15 Inverness Way East, Englewood, CO USA 8

5、0112-5776; Phone 800-854-7179; Fax 303-397-2740; Internet http:/; Email 2.2 Informative References 2.3 Informative References List AES17-1998 (r2004), AES Standard Method for Digital Audio Engineering Measurement of Digital Audio Equipment, March 3, 2004 2.3.1 Informative References Acquisition AES

6、 Standards: Audio Engineering Society, Inc., International Headquarters, 60 East 42ndStreet, Room 2520, New York, NY 10165-2520; Phone 212-661-8528; Fax 212-682-0477; Internet http:/www.aes.org/standards/ ; Email standardsaes.org 3 Symbols and Abbreviations AES Audio Engineering Society dB Decibel H

7、z Hertz IEC International Electrotechnical Commission kHz Kilohertz Ohm +/- Plus or minus RMS Root Mean Square CEA-2006-B 2THD Total Harmonic Distortion THD+N Total Harmonic Distortion plus Noise V Volt W Watt 4 Definitions 4.1 Power Amplifier A device whose purpose is to provide a larger output pow

8、er than its required input power over the audio range or portion thereof, normally construed to mean 20 Hz to 20 kHz. 4.2 Integrated Amplifier A power amplifier integrated into a device whose primary purpose is not power amplification. An integrated amplifier, for example, may be the amplifier conta

9、ined in a head-unit whose primary purpose is media playback or an amplifier contained in a signal processor whose primary purpose is equalization, filtering or multi-channel surround encoding or decoding. These examples are given for illustrative purposes and for purposes of clarification and are no

10、t intended to be all-inclusive. NOTEIn CEA-2006-B, the power amplifier section of a head-unit is considered an integrated amplifier. 4.3 Rated Characteristic A single value of a characteristic, such as power output, distortion, etc. claimed as representative of the performance of the product when me

11、asured in accordance with CEA-2006-B. 4.4 Rated Frequency The frequency, measured in Hz, at which the power amplifier is tested to measure other characteristics. NOTEThe Rated Frequency shall be stated in conjunction with the rated characteristic. 4.5 Rated Bandwidth The rated bandwidth shall be the

12、 frequency range between two stated values (e.g., 20 Hz to 20 kHz) over which the power amplifier is tested to measure rated characteristics. NOTE: The rated bandwidth shall be stated with the rated characteristic. 4.6 Rated Load The load impedance with which the power amplifier is designed to opera

13、te and upon which other characteristics are based. NOTEThe Rated Load shall be specified in any alternate or additional power rating measured in accordance with CEA-2006-B. 4.7 Rated Supply Voltage The supply voltage at which the power amplifier is tested to measure rated characteristics. NOTEThe Ra

14、ted Supply Voltage shall be stated in conjunction with the rated characteristic. CEA-2006-B 34.8 Reference Load The load impedance with which the power amplifier is tested in order to measure rated characteristics. NOTEThe Reference Load for primary power output ratings measured in accordance with C

15、EA-2006-B shall be 4 X (1 +/- 5%) . 4.9 Reference Supply Voltage The supply voltage at which the power amplifier is tested to measure rated characteristics. NOTEThe Reference Supply Voltage for primary power output ratings measured in accordance with CEA-2006-B shall be 14.4 V dc +/- 0.2 V dc. 4.10

16、Reference Characteristic A single value of a characteristic that is used as a reference for the measurement of another characteristic (e.g., input sensitivity is a Reference Characteristic for a signal-to-noise measurement, or total harmonic distortion is a Reference Characteristic for total power o

17、utput measurement). 4.11 Channel of Amplification, Bridged Channels A device containing at least one set of output terminals intended to power a loudspeaker(s) and that may incorporate any number of input terminals. An integrated amplifier, such as the amplifier incorporated in a head-unit or other

18、device, may not have accessible input terminals. For the purposes of CEA-2006-B, amplifier channels incorporated in devices of this type are considered channels of amplification, nonetheless. For a multichannel amplifier, bridging of channels is a condition where two (or more) channels of amplificat

19、ion are connected so that the channels operate as a single channel to provide additional output power when compared to a single channel. NOTEThe output power of bridged channels may be stated as an additional rating when the per-channel output power rating is stated. 4.12 Total Harmonic Distortion (

20、THD) The percentage of total harmonic distortion of a sine wave of fundamental frequency, f, is numerically equal to the ratio of 100 times the square root of the sum of the squares of the RMS voltages of each of the individual harmonics to the RMS voltage of the fundamental, expressed as a percenta

21、ge. NOTEFor CEA rating purposes, all harmonics whose amplitudes exceed 10% of the amplitude of the strongest harmonic component of the fundamental frequency shall be included in the summation. 4.13 Total Harmonic Distortion Plus Noise (THD+N) The percentage of Total Harmonic Distortion plus Noise is

22、 defined as the sum of the total harmonic distortion and noise generated by the power amplifier, expressed as a percentage. 4.14 Power Output The Power Output of a sinusoidal signal, expressed in watts, is the square of the output RMS voltage, measured with a voltmeter calibrated in true RMS at the

23、power amplifiers output terminals, divided by the resistance of the load. CEA-2006-B 44.15 A-Weighting Filter A specific noise-weighting filter used to produce noise measurements that correlate well with human observations. See IEC 60651 for details. 4.16 Clipping Clipping is the amplitude at which

24、the output of the amplifier cannot be increased without exceeding 1% THD compared to the input signal. 4.17 Primary Ratings Primary Ratings are those ratings deemed to be most representative of the performance of mobile audio power amplifiers. Primary Ratings are Power Output with Total Harmonic Dis

25、tortion Plus Noise and Signal-to-Noise Ratio, all measured at Reference Load and Reference Supply Voltage. Primary Ratings shall be indicated in product documentation. 4.18 Secondary Ratings Secondary Ratings are those ratings deemed to be of additional value in assessing the performance of power am

26、plifiers when considered along with the primary ratings. Secondary Ratings are: Dynamic Power, Effective Damping Factor, Frequency Response, Maximum Input Signal, Maximum Sensitivity, Output Regulation, and Additional Power Output Ratings. Secondary Ratings may be indicated in product documentation.

27、 4.19 Additional Power Output Ratings Additional power output ratings are a form of secondary rating that may be included with the primary output rating to indicate power output at rated loads other than 4 and rated supply voltages other than 14.4 V. All other test conditions shall be identical to t

28、hose used to measure primary power output. 5 Primary Rating Measurements Section 5 describes the measurement requirements for the required Primary Ratings. Additional information on the disclosure of rating information can be found at the end of CEA-2006-B. All measurements shall be made under stand

29、ard operating conditions with ambient temperature approximately 25C. Where necessary for devices without external audio inputs, such as headunits, test signals may be applied inside the device at the same point in the circuitry where the internal signal would enter or at the input audio selection (m

30、ultiplexing) point. Output shall be measured at available leads or terminals and not at an internal measurement point. When measuring switch-mode power amplifiers, such as Class-D topologies, it may be necessary to include a low pass filter between the amplifier output being measured and the measure

31、ment instrument. Many amplifiers using this technology produce output signals with slew rates that can significantly exceed the slew-rate capability of the input circuits of most measurement devices. If no filter is used, the input stage of the measurement instrument will slew-rate limit and thus be

32、come non-linear yielding inaccurate results. A suggested practice is to use a passive LCR low-pass filter to limit the slew rate to a level that is tolerable by the measurement instrument. 5.1 Primary Power Output Rating The Primary Power Output Rating of an amplifier or integrated amplifier shall b

33、e the square of the minimum RMS voltage delivered by the device during a measurement duration of one minute at the reference supply voltage (14.4 V +/- 0.2 V) into the reference load (4 +/-5%) with all channel driven, across the emplifiers stated operating bandwidth (or, if not stated, as defined in

34、 section 5.4) while maintaining no more than 1/0% THD+N, divided by 4 . CEA-2006-B 55.1.1 THD+N For full range and integrated amplifiers, rated THD+N shall be the greatest value of THD+N measured at the output terminals across the amplifiers operating bandwidth (defined as frequency response in Sect

35、ion 6.4) (limited to 20 Hz to 20 kHz). For bandwidth limited amplifiers, rated THD+N shall be the greatest value of THD+N measured at the output terminals at any frequency up to one half the published frequency response of the amplifier. When measuring THD+N, the input sensitivity setting for all ch

36、annels shall be 1 V RMS. The measurement shall be taken using a 22 kHz low-pass filter with a slope of no less than 12 dB per octave on the measurement equipment. The rated THD+N shall be calculated and expressed in accordance with the definition of THD+N in Section 4.13. 5.2 Signal-to-Noise Ratio T

37、he Signal to Noise ratio shall be measured using a 1.0 V RMS gain setting on the amplifier, with the amplifier driven to 2 V RMS (1 watt of output referenced to 4 ) using an A-weighted filter in conjunction with a low pass filter (- 240 dB/octave). The inclusion of the additional low pass filter is

38、to prevent out of band noise from adversely affecting the in-band measurement. For this use, the additional low pass filter shall drop response to less than -60 dB by 24 kHz, with +/- 0.1 dB flatness over the passband of 10 Hz to 20 kHz. One available version of this additional low pass filter is kn

39、own as an AES-17 Standard low pass filter. See AES-17. NOTEIf the amplifier under test at minimum gain setting exceeds 2 V RMS ouput, then the input audio test signal voltage may be reduced to a level below 1.0 V RMS to achieve 2 V RMS output. Upon removal of the input signal, the amplifiers input t

40、erminals shall be shorted and the noise output measured using an A-weighted filter. The published rating shall be the lowest Signal to Noise ratio of all channels measured in the case of multi-channel amplifiers. 6 Secondary Rating Measurements Section 6 describes the measurement requirements for th

41、e optional secondary ratings. Additional information on the disclosure of rating information can be found at the end of CEA-2006-B. 6.1 Additional Power Output Ratings For disclosure of power output other than primary power output rating, measurement characteristics other than the reference supply v

42、oltage and load may be used. However, all additional ratings shall state the rated frequency, supply voltage, load, and “no more than 1% THD+N “. For example, secondary power output may be stated at 15.8 V supply voltage into a 2 load with 60 Hz input and no more than 1% THD+N. The test duration for

43、 any additional power output ratings shall be one minute. See Section 5.1. 6.2 Dynamic Power Rating The Dynamic Power Rating of a full-bandwidth amplifier shall be the amount of power delivered during a 20 cycle burst of a 1 kHz input sinewave, while maintaining no more than 1.0% THD+N at the output

44、. This 1 kHz signal is on for 20 cycles and rested (at 20 dB) for 480 cycles. The Dynamic Power Rating of a bandwidth limited amplifier shall be the amount of power delivered during a 20 cycle burst of a 50 Hz input sinewave, while maintaining no more than 1.0% THD+N at the output. This 50 Hz signal

45、 is on for 10 cycles and rested (at 20 dB) for 20 cycles. These ratings shall be expressed in watts into a specified load impedance. CEA-2006-B 66.3 Effective Damping Factor Effective low-frequency damping factor at 4 is a simplified indication of the amplifiers ability to minimize unwanted (non sig

46、nal-resident) dynamic loudspeaker cone movement at the loudspeakers frequency of resonance. The simulated impedance peak of a loudspeaker at resonance is defined in CEA-490-A Section 5.13. The Resof the simulated load, which indicates the portion of the resistance of the speaker at resonance caused

47、by EMF generated by the voice coil moving in the magnetic gap, is defined by the mathematical formula: Res= Rpeak Revc= 20.5 Where, Rpeak = 23.7 (from CEA-490-A-5.13) Revc = 3.2 The DC resistance (Revc) of the simulated loudspeaker impedance is specified as 3.2 , which is the typical DC resistance f

48、or a loudspeaker having a nominal impedance of 4 . A nominal loudspeaker impedance of 4 corresponds to the Reference Load specified for Power Output Ratings in CEA-2006-B. To calculate the Effective Low-frequency Damping Factor of an amplifier, the output impedance of the amplifier shall be known an

49、d measured in accordance with CEA-490-A Section 5.10.3. Effective Low Frequency Damping Factor at 4 shall be calculated using the following mathematical formula and specified values: )Re(RevcZoutsEDF+= Where, Zout = Amplifier output impedance 6.4 Frequency Response Frequency Response (amplitude response versus frequency) shall be the range defined by the two half-power (- 3 dB) points at the high- and low-frequency extremes of the amplifiers response measured at a power output of 1 watt. For purposes of rating