1、 When the power amplifier meets the following amplification conditions, it is considered that the amplifier is operating under rated conditions. The amplifier is connected in series with the rated source electromotive force on the rated power supply, and then connected to the input and output terminals that do not use the rated impedance. The source electromotive force is connected according to regulations at the specified standard reference frequency of 1 Khz, so that its sinusoidal voltage is equal to the rated source electromotive force; The volume control should be in the position where the rated distortion and idle output voltage occur at the output end. The tone control should be in the flat frequency response position, and all sound processing functions should be turned off at normal room temperature and humidity. Arbitration testing must be conducted at the specified arbitration temperature and humidity. 1.2 Normal operating conditions: Place the amplifier under rated conditions and reduce the source electromotive force to 10dB lower than the rated source electromotive force, which is considered normal operating conditions. 2、 Power amplifier performance index measurement 1.0 Input impedance measurement 1.1 Index describes the impedance measured from the input end of the amplifier when the rated load resistance is connected to the output end of the amplifier. When a power amplifier with a front end is connected to the following input devices, the requirements for input impedance are: the microphone should be connected to the phonograph, recorder, and tuner with three preferred values of input impedance: ≥ 1k, ≥ 3k, and ≥ 10k, depending on the type of microphone. The input impedance of the amplifier should be preferred to be ≥ 47k1.2. The measurement of the input impedance of the balanced input amplifier is shown in Figure 11) Using an ungrounded source electromotive force, R1=R2, R1+R2=equal to the rated source impedance. R is a calibrated variable resistor, RL is the rated load impedance. 2) Place the amplifier under normal operating conditions and measure the input voltage u1 using a balanced input voltmeter (note that the input impedance of the voltmeter should be much greater than the input impedance of the amplifier). Record this value. 3) Turn the switch S to the adjustable resistor R, replace the amplifier with R, adjust the resistance value so that the reading of the voltmeter is still u1, and the current resistance value is the input impedance of the amplifier
Function of testing report:
1. Project bidding: Issue authoritative third-party CMA/CNAS qualification report
2. Online e-commerce platform entry: Quality inspection report recognized by major e-commerce platforms 3. Used as a sales report: issuing legally effective testing reports to make consumers more confident 4. Papers and research: Provide professional personalized testing needs 5. Judicial services: providing scientific, fair, and accurate testing data 6. Industrial problem diagnosis: Verify the troubleshooting and correction of industrial production problemsBaijian and testing process:
1. Telephone communication and confirmation of requirements
2. Recommend solutions and confirm quotations 3. Mail samples and arrange testing 4. Progress tracking and result feedback 5. Provide reports and after-sales service 6. If urgent or priority processing is requiredTesting and testing characteristics:
1. The testing industry is fully covered, meeting different testing needs
2. Fully cover the laboratory and allocate localized testing nearby3. Engineers provide one-on-one services to make testing more accurate
4. Free initial testing, with no testing fees charged
5. Self service order delivery for free on-site sampling
6. Short cycle, low cost, and attentive service 7. Possess authoritative qualifications such as CMA, CNAS, CAL, etc 8. The testing report is authoritative and effective, and is generally used in China