1、 CEA Standard Test Methods of Measurement for Audio Amplifiers CEA-490-A R-2008 December 2001 NOTICE Consumer Electronics Association (CEA) Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and
2、purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such Standards, Bulletins and other technical publications shall not in any respect preclude any
3、 member or nonmember of CEA from manufacturing or selling products not conforming to such Standards, Bulletins or other technical publications, nor shall the existence of such Standards, Bulletins and other technical publications preclude their voluntary use by those other than CEA members, whether
4、the standard is to be used either domestically or internationally. Standards, Bulletins and other technical publications are adopted by CEA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, CEA does not assume any liability to any patent owner, nor do
5、es it assume any obligation whatever to parties adopting the Standard, Bulletin or other technical publication. This CEA Standard is considered to have International Standardization implication, but the International Electrotechnical Commission activity has not progressed to the point where a valid
6、comparison between the CEA Standard and the IEC document can be made. This Standard does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health prac
7、tices and to determine the applicability of regulatory limitations before its use. (Formulated under the cognizance of the CEAs R3 Audio Systems Committee.) Published by CONSUMER ELECTRONICS ASSOCIATION 2008 Technology b) Standard language for primary ratings of amplifiers that allows consumers to m
8、ake an “apples-to-apples” comparison between various brands and models of amplifiers; c) Changes in the preconditioning power of amplifiers to make CEA-490-A consistent with changes made by the FTC to its Amplifier Rule as amended in the Federal Register on December 22, 2000; d) Changes in precondit
9、ioning operating time from one-hour to 30 minutes; and e) The inclusion of a formal Scope section in the standard that clearly defines the audio products are to be covered by CEA-490-A. NOTE-Self-powered loudspeakers (including powered speakers used in multimedia applications and powered subwoofers)
10、, as well as manufacturer-packaged audio and home theater systems (systems that include loudspeakers), are specifically not covered by CEA-490-A and may be considered under a separate standard-setting activity. iCEA-490-A-R2008 This page intentionally left blank. iiCEA-490-A-R2008 CONTENTS 1 Scope.1
11、 2 References1 2.1 Normative References1 2.1.1 Normative Reference List 1 2.1.2 Normative Reference Acquisition .1 3 Definitions of TermsGeneral .1 3.1 Power Amplifier 1 3.2 Preamplifier.2 3.3 Integrated Amplifier2 3.4 Amplifier 2 3.5 Receiver.2 3.6 Tuner/Preamplifier2 3.7 Rated Characteristic.2 3.7
12、.1 Rated Frequency.2 3.7.2 Rated Bandwidth.2 3.7.3 Rated Load 2 3.7.4 Nominal Load 2 3.8 Reference Characteristic .2 3.9 Channel of Amplification .2 3.10 Line Input.3 3.11 MM-Phono Input3 3.12 MC-Phono Input3 3.13 Percentage of Xth Harmonic Distortion .3 3.14 Percentage of Total Harmonic Distortion
13、(THD)3 3.15 Percentage of Weighted Total Harmonic Distortion (WTHD).3 3.16 Percentage of Total Harmonic Distortion Plus Noise (THD+N) .3 3.17 Percentage of SMPTE Intermodulation Distortion (SMPTE-IM).3 3.18 Percentage of Dual Tone Intermodulation Distortion.4 3.19 Transient Intermodulation Distortio
14、n (TIM) .4 3.20 Power Output 4 3.20.1 dBW4 3.21 Weighting 4 3.22 Clipping Point .5 3.23 Pink Noise .5 3.24 Slew Factor5 4 Standard Test Conditions .5 4.1 AC Power Line 5 4.2 Operating Temperature5 4.2.1 Power or Integrated Amplifier, or Receiver Preconditioning .5 4.2.2 Preamplifier Pre-Conditioning
15、.5 4.3 Input Reference Level 5 4.3.1 Line Input Terminals.5 4.3.2 MM-Phono Inputs5 4.3.3 MC-Phono Inputs 5 4.4 Output Reference Level .5 4.5 Load Impedance .6 4.6 Input Termination .6 4.6.1 Each Line.6 4.6.2 Each MM-Phono Input 6 iiiCEA-490-A-R2008 4.6.3 Each MC-Phone Input.6 4.7 Connection of AC Li
16、ne Cord .6 4.8 Control Settings6 4.8.1 Gain Control 6 4.8.1.1 Input-Gain .6 4.8.1.2 Balance6 4.8.2 Tone, Loudness-Contour and Other.6 4.9 Test Equipment.6 4.9.1 Test Frequency .6 4.9.2 Voltmeter .6 4.9.3 Harmonic Distortion Measurement Device 6 4.9.4 SMPTE Intermodulation-Distortion.7 4.9.5 Dual Ton
17、e Intermodulation Distortion 7 4.9.6 Spectrum Analyzer .7 4.9.7 Oscilloscope Display7 4.9.8 A-Weighted Noise Measurement Device 7 4.9.9 ITU-R/ARM Noise Measurement Device .7 5 Test and Ratings, Single-Channel Amplifiers .7 5.1 Power Output Rating7 5.2 Dynamic Headroom8 5.2.1 Output Level8 5.2.2 Maxi
18、mum Peak-to-Peak Output Voltage Level 8 5.2.3 Dynamic Headroom Rating8 5.3 Clipping Headroom.8 5.4 Total Harmonic Distortion .8 5.5 Maximum Voltage Output 9 5.5.1 Gain Control Settings.9 5.6 Output and Total Harmonic Distortion (THD) versus Frequency 9 5.7 Sensitivity9 5.8 Maximum Input Signal9 5.8.
19、1 Gain Adjustment from Single Input 10 5.8.2 Input Terminals Internet http:/www.gpo.gov/nara/cfr/index.html IEC Standards: Global Engineering Documents, World Headquarters, 15 Inverness Way East, Englewood, CO USA 80112-5776; Phone 800-854-7179; Fax 303-397-2740; Internet http:/; Email IEC Central
20、Office, 3, rue de Varembe, PO Box 131, CH-1211 Geneva 20, Switzerland; Phone +41 22 919 02 11; Fax +41 22 919 03 00; Internet http:/www.iec.ch; Email pubinforiec.ch ITU Standards: International Telecommunications Union, Place des Nations, CH-1211 Geneva 20, Switzerland; Phone +41 22 730 5111; Fax +4
21、1 22 733 7256; Internet http:/www.itu.int/publications/itu-r/index.html; Email itumailitu.int 3 Definitions of TermsGeneral Within the scope of CEA-490-A, the following definitions shall apply. 3.1 Power Amplifier A device having separate input and output terminals, whose purpose is to provide a lar
22、ger output power than its required input power over the audio range (or a portion thereof), normally construed to mean 20 Hz to 20 kHz. For CEA-490-A purposes, the term power amplifier shall also apply to the power amplifier section of an integrated amplifier or receiver. 1CEA-490-A-R20083.2 Preampl
23、ifier A device, having separate input and output terminals, whose purpose is to provide a larger output voltage than its required input voltage over the audio range (or a portion thereof), and/or to provide equalization and/or other controls whose primary function is the adjustment of frequency resp
24、onse and/or output signal level. For CEA-490-A purposes, the term preamplifier shall also apply to the preamplifier section of any combined audio amplifying product. 3.3 Integrated Amplifier A device combining the function of the power amplifier and the preamplifier, the two sections of which may be
25、, but need not be, electrically separable. Each section of an integrated amplifier whose power amplifier section is electrically separable from its preamplifier section may be rated separately, or the amplifier may be rated in toto as if such electrical separation did not exist, provided that the ra
26、tings clearly indicate to which section (or combination of sections) they apply. 3.4 Amplifier A general term referring to a power amplifier, a preamplifier, or an integrated amplifier. 3.5 Receiver The combination of a tuner and an integrated amplifier. CEA-490-A shall apply only to the amplifier p
27、ortion of a receiver. For the purposes of rating, said section shall be considered to be an integrated amplifier. 3.6 Tuner/Preamplifier The combination of a tuner and a preamplifier. CEA-490-A shall apply only to the preamplifier portion of a tuner/preamplifier. For the purpose of rating, said sect
28、ion shall be considered to be a preamplifier. 3.7 Rated Characteristic A single value of a characteristic, such as power output, distortion, etc. claimed as representative of the performance of the product and measured in conformance with the tests described in CEA-490-A. 3.7.1 Rated Frequency The f
29、requency at which the performance of an amplifier is tested to measure other characteristics, such as power output, distortion, etc. For CEA-490-A purposes, the rated frequency is 1 kHz. 3.7.2 Rated Bandwidth The frequency range, normally designated by two frequencies (e.g., 20 Hz and 20 kHz) betwee
30、n which the performance of an amplifier is tested to measure other characteristics such as power output, distortion, etc. 3.7.3 Rated Load The load impedance(s) into which the power amplifier is designed to operate and upon which other characteristics, such as power output, distortion, etc. are base
31、d. 3.7.4 Nominal Load The load impedance at which the power amplifier is tested to measure other characteristics such as power output, distortion, etc. For CEA-490-A purposes, the nominal load is 8 ohms. 3.8 Reference Characteristic A single value of a characteristic such as input-signal level, outp
32、ut-signal level, etc. that is used as a reference for the measurement of other characteristics, such as sensitivity, noise, etc. 3.9 Channel of Amplification A channel of amplification shall contain at least one set of input terminals and at least one set of output terminals. A multi-channel amplifi
33、er shall fulfill these requirements per channel of amplification and shall be capable of amplification in any one channel substantially independent of simultaneous amplification in all other channels of amplification. 2CEA-490-A-R20083.10 Line Input Any set of input terminals of an amplifier whose p
34、rimary function is to accept line-level input signals, normally construed to mean input levels in excess of 250 mV. 3.11 MM-Phono Input Any set of input terminals of an amplifier whose primary function is to accept input signals from a moving-magnet, induced-magnet, or other level and impedance-equi
35、valent phono cartridge and to provide appropriate equalization to such signals. As a point of clarification, such inputs are normally designed to operate from a phono cartridge whose sensitivity is of the order of 0.5 to 2.0 mV/cm/s and is meant to be terminated with an impedance of greater than 10
36、k ohms. 3.12 MC-Phono Input Any set of input terminals of an amplifier whose primary function is to accept input signals from a low impedance moving-coil or other level- and impedance-equivalent phono cartridge and to provide appropriate equalization to such signals. As a point of clarification, suc
37、h inputs are normally designed to operate from a phono cartridge whose sensitivity is of the order of 200 V/cm/s or less, and that is meant to be terminated with an impedance of less than 10 k ohms. 3.13 Percentage of Xth Harmonic Distortion The percentage of Xth harmonic distortion of a sine wave o
38、f frequency f is numerically equal to 100 times the ratio of the RMS voltage of the signal component at frequency Xf, to the RMS voltage of the signal component at frequency f. 3.14 Percentage of Total Harmonic Distortion (THD) The percentage of total harmonic distortion (THD) of a sine wave of freq
39、uency f is numerically equal to 100 times the ratio of the square root of the sum of the squares of the RMS voltages of each of the individual harmonic components, to the RMS voltage of the fundamental. NOTEFor rating purposes, all harmonics whose amplitude exceeds 10% of the amplitude of the strong
40、est harmonic component shall be included in the summation. 3.15 Percentage of Weighted Total Harmonic Distortion (WTHD) The percentage of weighted total harmonic distortion (WTHD) of a sine wave of frequency f is numerically equal to 100 times the ratio of the square root of the sum of the squares o
41、f the amplitudes of each of the individual harmonics, each weighted in accordance with a particular algorithm, to the RMS voltage of the fundamental. NOTEFor rating purposes, all harmonics used shall be stated and all harmonics whose weighted amplitude exceeds 10% of the strongest weighted amplitude
42、 shall be included in the summation. 3.16 Percentage of Total Harmonic Distortion Plus Noise (THD+N) The percentage of total harmonic distortion plus noise (THD+N) is defined as the reading of a device that measures in accordance with 4.9.3. NOTEFor rating purposes, a measurement of THD+N may be sub
43、stituted for a measurement of THD, wherever the latter is called for, however, such measurement shall be designated as (THD+N). 3.17 Percentage of SMPTE Intermodulation Distortion (SMPTE-IM) The percentage of SMPTE intermodulation distortion (SMPTE-IM) of a composite signal composed primarily of two
44、 sinusoidal signals, one having a relatively low frequency (f1) and the other having a relatively high frequency (f2); the low frequency sine wave having an amplitude 4 times greater than that of the high frequency sine wave, shall be the reading of a device that measures in accordance with 4.9.4. 3
45、CEA-490-A-R2008NOTEFor CEA-490-A purposes, f1shall equal 60 Hz, and f2shall equal 7 kHz. The percentage of SMPTE-IM is equivalent to 100 times the ratio of the average variation in amplitude of the higher frequency to the amplitude of the higher frequency (see 4.9.4). 3.18 Percentage of Dual Tone In
46、termodulation Distortion The percentage of dual tone intermodulation distortion of a composite signal composed primarily of two relatively high frequency sinusoidal signals, one having a frequency f1and the other having a frequency f2, of equal amplitude, is numerically equal to 100 times the square
47、 root of the sum of the squares of the second-through fifth-order distortion components divided by the square root of the sum of the squares of the amplitudes of the components at frequencies f1and f2, as follows: ( )()2f22f12f52f42f3VVVVV% Distortion IM+= where: Vf1 = RMS voltage 19 kHz Vf2 = RMS v
48、oltage 20 kHz Vf3 = RMS voltage 1 kHz Vf4 = RMS voltage 18 kHz Vf5 = RMS voltage 17 kHz The second-order distortion components are defined as the two components at frequencies f1f2. The third-order distortion components are defined as the four components at frequencies 2f1f2and 2f2f1. The fourth-ord
49、er distortion components are defined as the two components at frequencies 2f12f2. The fifth-order distortion components are defined as the four components at frequencies 3f12f2and 3f22f1. NOTEFor rating purposes, all distortion components whose frequency is less than or equal to 20 kHz and whose amplitude exceeds 10% of the amplitude of the strongest distortion component shall be included in the summation. 3.19 Transient Intermodulation Distortion (TIM) Transient Intermodulation Distortion (TIM) is a form of dynamic intermo
