This standard applies to the measurement of basic characteristics of professional and other mixing consoles. When the mixing console is equipped with power amplifiers, reverberators, frequency shifters and automatic control circuits, the measurement of these characteristics shall be carried out in accordance with relevant standards. The safety, interference and other characteristics of the mixing console shall be measured in accordance with relevant standards. GB/T 9003-1988 Measurement method of basic characteristics of mixing consoles GB/T9003-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
GB/T9003—1988bzxZ.net
Methods of measurement for the fundamental characteristics of mixing console
Mothods of measurement for the fundamental characteristics of mixing console1988-01-14Promulgated
Implemented on 1988-10-01
Ministry of Electronics Industry of the People's Republic of China
National Standard of the People's Republic of China
Methods of measurement for the fundamental characteristics of mixing console
Mothods of measurement for the fundamental characteristics of mixing consoleGB/T9003—1988
This standard is formulated with reference to some clauses of the international standard IEC268-3 "Sound system equipment, part 3: amplifiers". Other measurement methods that can obtain equivalent results are allowed. This standard applies to the measurement of the fundamental characteristics of mixing consoles for professional and other purposes. When the mixing console is equipped with power amplifiers, reverberators, frequency shifters and automatic control circuits, the measurement of these characteristics shall be carried out in accordance with relevant standards. The safety, interference and other characteristics of the mixer are measured in accordance with relevant standards. 1 Measurement conditions
1.1 Environmental conditions:
a. Temperature: 15~35℃;
b. Humidity: 45%~75%
c. Atmospheric pressure: 86106kPa.
1.2 The difference between the power supply voltage and the standard value during measurement shall not exceed ±2%. When using AC power supply, the frequency shall be 50±1Hz. The power supply waveform distortion shall not exceed 5%, and the ripple voltage shall not exceed 1mV when using DC regulated power supply. 1.3 Interference from external electromagnetic fields shall be avoided during measurement. 1.4 Rated normal operating conditions:
When the following conditions are met, the mixer is in rated normal operating conditions. Note: The rated values ​​in the following conditions are obtained from the parameters given by the manufacturer. 1.4.1 The mixer is connected to the rated power supply.
1.4.2 The rated source electromotive force is connected in series with the rated source impedance and then connected to the input terminal of the mixer. Note: If the manufacturer does not specify the rated source impedance, it shall be determined in accordance with relevant regulations. 1.4.3 The output terminal of the mixer is connected to the rated load impedance. 1.4.4 Unused terminals are connected as required.
1.4.5 The volume controller of the channel under test is placed at the rated gain position, and the volume controllers of the other channels are placed at the minimum gain position. The method for determining the rated gain is as follows: adjust the signal source frequency to the standard reference frequency of 1000Hz so that the output voltage of the signal source is equal to the rated source electromotive force, and adjust the channel volume controller so that the output of the mixer reaches the rated normal working level. Then the channel is at the rated gain. When the channel under test has more than one volume controller, the manufacturer shall provide the position of each volume controller. When there is a variable gain amplifier in the channel under test, the corresponding rated gains can be determined at different gain points of this amplifier. After the rated gain is determined by adjustment, if there is no special explanation, the characteristic measurement is carried out in this case, and the volume controllers are no longer adjusted. 1.4.6 The tone controller, equalizer, filter, etc. in the measured channel are placed in a position that can give the specified frequency response, generally a flat frequency response position.
1.5 Measurement frequency:
The standard reference frequency for measurement is 1000Hz, and the preferred frequency is the frequency specified in GB3240 "Common Frequencies in Acoustic Measurement". 1.6 Others:
1.6.1 When measuring a mixer with automatic control circuits and other special circuits, in addition to measuring the automatic characteristics of the control circuit, the control circuit should be disabled. The control circuit refers to the limiter, compressor, expander, electronic volume control circuit, and compensation circuit. 1.6.2 If the measured channel has several rated gains (see 1.4.5), the characteristic measurement can be carried out under the corresponding state. 1.6.3 After measuring each channel, the channels working simultaneously can be placed under rated normal working conditions according to the manufacturer's regulations, and representative channels can be selected to measure their characteristics.
2 Measurement method
2.1 Input characteristics
2.1.1 Input impedance
2.1.1.1 Characteristics description
Internal impedance measured between input terminals. 2.1.1.2 Balanced input measurement method
a. Connect as shown in Figure 1, place the mixer under rated normal working conditions, the signal source is not grounded (casing), and the frequency is adjusted to 1000Hz. 0
Test center
Figure 1 Balanced input impedance measurement block diagram
b. Use a balanced input voltmeter to measure the input voltage U1. The input impedance of the voltmeter should be much higher than the input impedance of the mixer. c. Replace the input of the mixer with a calibrated variable resistor R, adjust the resistance value so that the reading on the voltmeter is U1, and the resistance value of R is equal to the modulus of the mixer input impedance at 1000Hz. d. Measure the input impedance at the preferred frequency. Note: When the input is in a suspended state, it is allowed to measure by the unbalanced method. 2.1.1.3 Unbalanced input measurement method
a. Connect as shown in Figure 2.
Figure 2 Block diagram of unbalanced input impedance measurement
b. The measurement method is the same as in Section 2.1.1.2.
2.1.2 Overload source electromotive force
2.1.2.1 Characteristic description
The maximum source electromotive force when the mixer is under rated normal working conditions and the volume control is placed in the appropriate position to produce rated harmonic distortion at the output end of the mixer.
2.1.2.2 Measurement method
a. The mixer is placed under rated normal working conditions. b. Increase the source electromotive force, and adjust the volume controller of the channel under test one by one to restore the output to the rated normal working output level until its total harmonic distortion reaches the rated value.
c. Measure the source electromotive force E. , which is the overload source electromotive force of the channel under test. d. Measure the overload source electromotive force at other rated gains of this channel. 2
GB/T9003—1988
Note: ① According to the rated source electromotive force B and the overload source electromotive force E, calculate the input overexcitation capability (expressed in decibels) according to the following formula. H=201og10g.
② When there is more than one volume controller in the channel under test, the overexcitation capability of the circuit in front of each volume controller can be measured one by one. At this time, the volume controllers of each channel under test are set to the rated gain, increase the source electromotive force, and adjust the position of the measured volume controller one by one to restore to the rated normal working output level until the rated total harmonic distortion is obtained. Measure the overload source electromotive force E\, and its overexcitation capability (expressed in decibels) is calculated according to the following formula. H=201og10F
2.2 Output source impedance
2.2.1 Characteristics
The internal impedance measured between the output terminals under specified conditions. 2.2.2 Measurement method
a. The mixer is placed under rated normal working conditions, the source electromotive force is reduced to zero, and the load resistor is not connected. b. A sinusoidal signal source for measurement is connected in series with the resistor R to replace the load resistor, as shown in Figure 3. Lp
Source under test
Figure 3 Output source impedance measurement block diagram
c. Adjust the output of the measurement signal source so that the rated normal working level is obtained at the output end of the mixer. d. Measure the output voltage U? and the voltage drop UR on the series resistor R. e. The output source impedance is calculated according to the following formula.
f. The measurement frequency is 1000Hz.
Note: The selection of the R value should be close to the output source impedance of the mixer and should not overload the measurement signal source. 2.3 Gain
2.3.1 Maximum electromotive force gain
2.3.1.1 Characteristic description
The electromotive force gain measured when all volume controllers in the measured channel are set to the maximum gain position. 2.3.1.2 Measurement method
a. The mixer is placed under rated normal working conditions. @
b. All volume controllers of the measured channel are placed at the maximum gain position, reducing the source electromotive force and restoring the original output level under rated normal working conditions.
c. Measure the output voltage U2.
d. Measure the source electromotive force Es.
e. The maximum electromotive force gain is calculated according to the following formula. In ratio:
In decibel:
2.3.2 Attenuation characteristics of volume controller
2.3.2.1 Description of characteristics
GB/T9003—1988
201og10E
The relationship between the attenuation of the volume controller and the mechanical position of the controller is expressed in decibels. This characteristic can be represented by a graph. The attenuation characteristic may be a function of frequency.
2.3.2.2 Measurement method
a: Except for the volume controller under test being placed at the maximum gain position, the mixer is placed under rated normal working conditions. b. Measure the output voltage U2.
c. Adjust the volume controller step by step, record the position of the volume controller for each adjustment step, and measure the output voltage U2. d. The output voltage U is compared with the output voltage U? measured at each step, expressed in decibels: U2
N=20log1ou
e. Use a table or graph to express the relationship between these ratios N and the position of the volume controller. f. Measure at other preferred frequencies.
2.3.3 Attenuation characteristics of multi-channel balance controllers 2.3.3.1 Description of characteristics
Express the relationship between the attenuation characteristics of the balance controller and the mechanical position of the controller in decibels. 2.3.3.2 Measurement method
a. The mixer is placed under rated normal working conditions, and the balance controller is first adjusted to the maximum gain position of the channel under test, and the source electromotive force is only added to this channel.
b. Measure the output voltage U2.
c. Adjust the balance controller step by step, record the position of the balance controller for each adjustment step, and measure the output voltage U'2. d. The output voltage U2 is compared with the output voltage U'2 measured at each step, expressed in decibels: U2
N=201og10
e. Use a graph to represent the relationship between these ratios N and the position of the balance controller. f. Repeat the above measurements on other channels controlled by the controller. g. The measurement can be repeated at other preferred frequencies. Note: Plot all characteristics controlled by the same balance controller on the same graph. 2.4 Response
2.4.1 Gain-Frequency Response
2.4.1.1 Description of Characteristics
The ratio of the mixer's gain at different frequencies to the gain at a specific reference frequency is expressed in decibels. 2.4.1.2 Measurement method
a. The mixer is placed under rated normal working conditions, and the signal source is placed at a specific reference frequency, generally 1000Hz. b. Measure the source electromotive force E. and the mixer output voltage U2. c. Continuously or step by step change the signal source frequency, keep the source electromotive force unchanged, and measure the output voltage U2 at each frequency. d. The ratio of the output voltage at each frequency to the output voltage at a specific frequency, expressed in decibels: U'2
N=201og10U
e. Use a graph to show the relationship between these ratios and frequency. 2.4.2 Phase-frequency response
2.4.2.1 Characteristic description
GB/T9003—1988
The relationship between the phase difference between the output voltage and the source electromotive force and the frequency of the mixer under rated normal working conditions. If there is a controller, place it in the specified position.
2.4.2.2 Measurement method
a. The mixer is placed under rated normal working conditions. b. Connect the phase difference meter to the signal source and the output of the mixer, and pay attention to the terminal markings. c. Continuously or step-by-step change the frequency of the signal source and measure the phase difference at each frequency. d. The phase difference A@ is expressed in radians or degrees, or in time difference (in microseconds). The value of can be calculated using formulas (5) and (6): ex10%
AQx10%
e. These values ​​are represented graphically as a function of frequency. 2.5 Amplitude nonlinearity
2.5.1 Total harmonic distortion
2.5.1.1 Characteristic description
The unit of Ap is radians
The unit of A is degrees
··(5)
When a sine wave is input to the mixer, due to the amplitude nonlinearity of the mixer, frequencies that are not in the input signal appear at the output, and these new frequencies are integer multiples of the input signal frequency. Total harmonic distortion is a function of signal amplitude and frequency. 2.5.1.2 Measurement method
a. Place the mixer under rated normal operating conditions. b. Connect a harmonic distortion meter to the output terminal and measure the total harmonic distortion percentage. c. Reduce the signal source electromotive force to zero and check the measurement signal-to-noise ratio, which should be greater than 10dB. d. Increase the signal source electromotive force and measure at different output voltage values ​​until the output voltage value with rated distortion is reached, which is the maximum output voltage.
e. Measure at other preferred frequencies, at least at the upper and lower limits of the frequency range. 2.5.2 Intermodulation distortion
2.5.2.1 Characteristic description
Sinusoidal signals with frequencies equal to f and f2 are fed into the input terminal of the mixer. Due to modulation caused by nonlinearity, intermodulation frequencies appear at the output terminal. 2.5.2.2 Measurement method
a. Place the mixer under rated normal operating conditions. b. Connect the output end to the intermodulation distortion meter, adjust the frequency and amplitude of f1 and f2 according to the following requirements, and measure the intermodulation distortion. The amplitude ratio of f1 and f2 at the input end is 4:1. f1 should be selected between 0.5 and 1.5 octaves higher than the lower limit of the effective frequency range. f2 should be selected between 0.5 and 1.5 octaves lower than the upper limit of the effective frequency range. And meet fiReduce the signal source electromotive force to zero, check the measurement signal-to-noise ratio, which should be greater than 10dB. d. Increase the signal source electromotive force and measure at different output voltage values ​​until the output voltage value with rated distortion is reached, which is the maximum output voltage.
e. Measure at other preferred frequencies, at least at the upper and lower limits of the frequency range. 2.5.2 Intermodulation distortion
2.5.2.1 Characteristics description
Sinusoidal signals with frequencies equal to f1 and f2 are sent to the input end of the mixer. Due to the modulation caused by nonlinearity, intermodulation frequencies appear at the output end. 2.5.2.2 Measurement method
a. The mixer is placed under rated normal working conditions. b. Connect the intermodulation distortion meter to the output end, adjust the frequency and amplitude of f1 and f2 according to the following requirements, and measure the intermodulation distortion. The amplitude ratio of f1 and f2 at the input end is 4:1. f1 should be selected between 0.5 and 1.5 octaves higher than the lower limit of the effective frequency range. f2 should be selected between 0.5 and 1.5 octaves lower than the upper limit of the effective frequency range. And satisfy fiReduce the signal source electromotive force to zero, check the measurement signal-to-noise ratio, which should be greater than 10dB. d. Increase the signal source electromotive force and measure at different output voltage values ​​until the output voltage value with rated distortion is reached, which is the maximum output voltage.
e. Measure at other preferred frequencies, at least at the upper and lower limits of the frequency range. 2.5.2 Intermodulation distortion
2.5.2.1 Characteristics description
Sinusoidal signals with frequencies equal to f1 and f2 are sent to the input end of the mixer. Due to the modulation caused by nonlinearity, intermodulation frequencies appear at the output end. 2.5.2.2 Measurement method
a. The mixer is placed under rated normal working conditions. b. Connect the intermodulation distortion meter to the output end, adjust the frequency and amplitude of f1 and f2 according to the following requirements, and measure the intermodulation distortion. The amplitude ratio of f1 and f2 at the input end is 4:1. f1 should be selected between 0.5 and 1.5 octaves higher than the lower limit of the effective frequency range. f2 should be selected between 0.5 and 1.5 octaves lower than the upper limit of the effective frequency range. And satisfy fi
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