Multimedia speaker test standards

Test equipment:
Distortion tester/dual-channel oscilloscope/signal generator/dual-channel communication millivoltmeter/load resistance 4 ohm/load resistance 6 ohm/load resistance 8 ohm/(BTL default 8 ohm)
Instrument connection:
a. The load resistance is connected to the output of the amplifier
b. Correct wiring diagram of distortion tester, dual-channel oscilloscope, dual-channel communication millivoltmeter and load resistance parallel instrument
Test method and process:
One. Undistorted power test
1. Additional output power of satellite box channel
Input 1khz, 500mv sine wave signal source (the resistance of the load resistance is 4 ohms; if not specified, the BTL circuit is 8 ohms). Adjust the main volume potentiometer to the maximum volume (THD 10%), read the communication millivoltmeter value, and calculate the additional output power according to P=U2/R (when testing the power, each channel is required to be tested independently)
2. Extra output power for low voice channel
Input 70hz, 200mv sine wave signal source, (load resistance is 4 ohms, BTL resistance is 8 ohms). The low-sound volume potentiometer is placed in the maximum output condition (THD status 10%, the distortion meter appears), read the communication millivoltmeter value, and calculate the additional output power according to P=U2/R (when testing the low-sound channel power, satellites are required Loads are added to the box channels)
two. Channel separation
Input 1khz, 500mv sine wave signal source, adjust the main volume potentiometer to make the output power 1W (4 ohm load is 2V, 8 ohm load is 2.828V, 6 ohm load is 2.45V), remove the other One-channel signal source, read the left and right channel data from the dual-needle millivoltmeter, the R/L channel difference>=37db.
three. Channel balance (satellite box channel balance)
Input 1khz, 500mv sine wave signal source, adjust the main volume, and investigate the db value on the two-channel communication millivoltmeter together. The difference between L/R channels at any output point should be <=1db
Four harmonic distortion
1. Satellite box channel total harmonic distortion
a. Input a 1khz, 500mv sine wave signal source and adjust the main volume potentiometer to make the output power 1W (2.0V for 4 ohm load, 2.828V for 8 ohm load, 2.45V for 6 ohm load), Choose the appropriate range of the distortion test instrument.
b. Investigate the degree of distortion from the distortion meter. If not specifically stated, the degree of distortion of the test result is required to be <=1%
2. The total harmonic distortion of the low sound box channel
a. Input a 70,200mv sine wave signal source, adjust the main volume potentiometer to make the output power 1/5 of the extra power, and select the appropriate range of the distortion meter.

b. Investigate the degree of distortion from the distortion meter. If not specifically stated, the degree of distortion of the test result is required to be <=1%

Fives. Signal-to-noise ratio
1. Satellite box channel signal-to-noise ratio
a. Input a 1khz, 500mv sine wave signal source and adjust the main volume potentiometer to make the output power 1W (2.0V for 4 ohm load, 2.828V for 8 ohm load, 2.45V for 6 ohm load), Write down the level at the moment to data A
b. Remove the signal source
c. Select the appropriate range of the dual-needle millivoltmeter, read the level logarithm value B, and then calculate the level difference between A and B to be the satellite box signal-to-noise ratio
d. (line input) broadband >=65db
2. The signal-to-noise ratio of the low-sound gun channel
a. Input a 1khz, 500mv sine wave signal source, adjust the main volume potentiometer to make the output power 1/5 additional output power, write down the level value A at the moment
B. Remove the signal source
C. Select the appropriate range of the dual-needle millivoltmeter, read the level value B, and then calculate the A/B level difference to be the low-channel communication signal-to-noise ratio
d. (line input) broadband >=65db
Six. The biggest hum
1. The biggest hum of the satellite box channel
a. Set the main volume potentiometer to the maximum position
b. Remove the signal source
c. Select the appropriate range of the dual-needle millivoltmeter, and read the level value as the maximum hum
d. The maximum hum is required<=3mv
2. The maximum hum of the low-pitched gun channel
a. Set the main volume potentiometer to the maximum position
b. Remove the signal source
c. Select the appropriate range of the dual-needle millivoltmeter, and read the level value as the maximum hum
d. The maximum hum is required <=5mv
Seven. Smallest hum
1. Satellite box amplifier minimum hum
a. Turn the main volume potentiometer to the minimum
b Select the appropriate range of the dual-needle millivoltmeter, and the read level value is the smallest hum
c requires minimum hum<=1mv
2. The minimum hum of the bass amplifier
a. Turn off the main volume potentiometer and the low tone potentiometer to the minimum
b Select the appropriate range of the dual-needle millivoltmeter, and the read level value is the minimum value
d. Minimum hum is required<=1mv
Eight. Frequency response
1. Satellite box channel frequency response
a. Input a 1khz, 500mv sine wave signal source, and let the amplifier work at an output power of 1W (2.0V for a 4 ohm load, 2.828V for an 8 ohm load, and 2.45V for a 6 ohm load).
b. Regulate the signal generator, make the frequency attenuate to the low end based on 1khz, check the millivoltmeter together, when the level value attenuates to -3Db, write down the low end frequency value
c. Regulate the signal generator, make the frequency increase to the high end based on 1khz, and check the millivoltmeter together, when the level value attenuates to -3Db, write down the high end frequency value
d. The frequency value of the B/C item is the frequency response of the satellite box channel
2. Frequency response of bass box channel a. Input 70hz, 200mv sine wave signal source, let the amplifier work test under 1/5 extra power condition
b. Regulate the signal generator, make the frequency attenuate to the low end based on 70hz, and check the millivoltmeter together, when the level value attenuates to -3Db, write down the low end frequency value
c. Adjust the signal generator to increase the frequency to the high end based on 70hz, and check the millivoltmeter together. When the level value attenuates to -3Db, write down the high end frequency value.
d. The frequency value of the B/C term is the frequency response of the bass channel
nine. Input sensitivity
1. Satellite box channel input sensitivity
Input 1khz, 500mv sine wave signal source, turn the main volume potentiometer of the amplifier to the maximum position, adjust the fluctuation of the signal source so that the output reaches the additional distortion constraint output power (THD=10%), the size of the signal source output fluctuation is the satellite box channel Enter the sensitivity. (When testing the input sensitivity of the satellite box channel, the satellite box channels are required to be loaded)
2. Low sound box channel input sensitivity
Input a sine wave signal source of 70hz, 200mv, turn the amplifier main volume potentiometer to the maximum position, adjust the fluctuation of the signal source to make the output additional distortion limit the output power (THD = 10%), the size of the signal source output fluctuation is the low sound channel input Sensitivity. (When testing the input sensitivity of the bass box channel, each channel is required to be loaded)
ten. input resistance
1. Satellite box amplifier input impedance
a. Connect a variable resistor in series with the signal source input loop. As shown below.
Multimedia Active Speaker Test Specification
b. Turn the main volume potentiometer of the amplifier to the maximum, adjust the fluctuation of the signal source to make the output reach the extra power condition (THD=10&)
c. Change the resistance of the variable resistor to attenuate the amplifier output by 6db
d. Measuring the resistance of the variable resistor is the input impedance
eleven. Power consumption of the whole machine
a. Use 4.7K resistors to block and mix the output of the two signal generators. One has an output frequency of 1KHZ, and the other has an output frequency of 70HZ. See the diagram below for the connection of the instrument.
Multimedia Active Speaker Test Specification
b. Connect a communication ammeter in series with the 220v input circuit of the active speaker to monitor the current size
c. Connect the mixed signal source (the signal fluctuates according to different models) into the amplifier input
d. Regulate the signal generator A, so that the satellite box channel output reaches the voltage value when the output power of 1/8 additional distortion is constrained. Regulate the signal generator B, so that the output of the low sound gun channel reaches the voltage value of the extra distortion constrained output power ( The main volume potentiometer and low volume potentiometer are placed in the maximum position)
e. Read the reading of the ammeter, and calculate the power consumption of the whole machine according to the formula P=IU
12. Tweeter control (satellite box channel)
a. Input 10khz sine wave signal, make the amplifier work in 1W output condition, and base on the db value displayed by the dual-channel millivoltmeter (balance potentiometer of satellite box channel, high pitch potentiometer/low pitch potentiometer are all placed in the middle Point position)
b. Attenuation treble potentiometer, monitors the db value dropped by the dual-channel millivoltmeter, this data is the treble attenuation parameter
c. Increase the treble potentiometer, monitor the rising db value of the dual-channel millivoltmeter, this data is the treble increase parameter
13. Low voice control (satellite box channel)
A. Input a 100khz sine wave signal, make the amplifier work at 1W output condition, and take the db value displayed by the dual-channel millivoltmeter as the reference; (the balance potentiometer of the satellite box channel, the high pitch potentiometer, and the low pitch potentiometer are all placed at the midpoint position)
B. Attenuation low sound potentiometer, monitors the db value dropped by the dual-channel millivoltmeter, this data is the low sound attenuation parameter
C. Increase the whisper potentiometer to monitor the rising db value of the dual-channel millivoltmeter. This data is a whisper increase parameter
Clarification: If the speaker to be tested has no low-voice control function design, there is no need to test this parameter
14. Tone tone control; (satellite box channel)
A. Input a 10khz sine wave signal, make the amplifier work at 1W output condition, and use the db value displayed by the dual-channel millivoltmeter as the reference (the tuning potentiometer of the satellite box channel is placed in the midpoint position)
B. Attenuation tone potentiometer, monitors the db value dropped by the dual-channel millivoltmeter, this data is the tone tone attenuation parameter
C. Increase the tone potentiometer to monitor the rising db value of the dual-channel millivoltmeter. This data is the tone enhancement parameter
Clarification: If the active speaker to be tested has no tone control function design, it is not necessary to test this parameter
15. Balance control:
A. Input 1khz .500mv sine wave signal, make the amplifier work in 1W output condition (balance potentiometer of satellite box channel, high pitch potentiometer. Low pitch potentiometers are all placed in the midpoint position)
B. Turn the balance potentiometer counterclockwise to the minimum position, and investigate the level value of the two pointers on the dual-channel communication millivolt meter. The difference between the two pointer readings is the balance control parameter (when the balance potentiometer is turned clockwise to the maximum position, the parameter should be Same as the parameter of the minimum orientation) Balance control>=40db
16: The temperature rise test of the whole machine
Input signal source: 1khz and 70hz mixed dual-frequency sine wave signal (2.0 channel active speakers only input 1khz sine wave signal), the input fluctuation is determined by the input sensitivity of different models.
Load setting: satellite box channel connection load resistance 4 ohm (if not specifically stated, BTL circuit uses 8 ohm load)
The low sound channel is connected to the speaker used by this model (different models have different speaker impedances)
Temperature test point setting:
1. Power IC
A. Only use 1 single in-line package (SIP) power amplifier integrated circuit, the test point is on the integrated circuit
B. Regarding the use of two single-in-line package (SIP) power integrated circuits, if the distance is close, the test point is taken at the center of the two integrated circuits; if the distance is far apart, the test point is taken on the two integrated circuits separately
C. Regarding the dual-row DIP package attack and release integrated circuit, the test point is on the ground pin (GND)
2. Rectifier diode and rectifier bridge stack
A. The rectifier circuit uses diodes, and the test point is at the anode of the first diode
B. The rectifier circuit uses a bridge stack, and the test point is taken on the output pin of the positive power supply of the bridge stack
Test process:
A. Make the satellite channel and the low voice channel work at 1/8 extra output power condition
B. Test and record the temperature rise data every half an hour. It is necessary to monitor for 4 consecutive hours
C. Investigate the temperature rise within 4 hours to ensure that the temperature is stable. If the temperature rises, continue the temperature rise test until the temperature stabilizes and stops.
d. The maximum temperature requirement of the power amplifier integrated circuit is less than 75 degrees, and the temperature of the rectifier diode and the rectifier bridge stack cannot exceed the maximum temperature requirement of this type. (The maximum temperature requirement does not include the ambient temperature)
Seventeen: Innovative model speaker unit and speaker vibration, air leakage inspection specifications
Inspection and application equipment: audio frequency scanner, computer sound card audio output equipment
The calculation method of voltage and sweep frequency setting is as follows:
1. Satellite machine
A voltage setting, the voltage calculated based on 1/5 of the power of the satellite speaker unit is the setting voltage
B. Sweep frequency scale, Fmin~20KHZ (Fmin is 80% of the single resonance frequency)
2. Silent Cannon
a. Voltage setting, calculated according to the formula Gmain=20lg(V0/VI), during which Vo is calculated by 3/4 additional output power.
B. Sweep frequency scale, Fmin~20khz (Fmin is 80% of the single resonance frequency)
The inspection items and requirements are detailed below
Multimedia Active Speaker Test Specification
FTC Means: Federal Trade Commission FTC Test (Federal Trade Commission)
1. All channels are loaded with load (the size of the load is determined according to the circuit of different models), input (1k+70hz) mixed signal, so that the output operation is at 1/8 extra output power condition, and the operation is 1 hour under this condition
After 2.1 hours, the satellite channel output reaches THD=10% (the low sound channel remains unchanged) for 5 minutes
3. The job records the output power of each channel
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