小弟 ,公司作耳机, 软件SOUNDCHECK, G,R,A,S的MICROPHONE, COUPLE是IEC711,做校验是用B&K 4228 ,请问为什么要用B&K 4228 ,来校验.他只发出250Hz的声音, 这样如何对 高频部分校验? 或者是小弟对校验的概念 理解有错误?! 另外在和装4228的盒子里还有 一个仪器叫UZ1000,圆盘样的, 那东西是做什么
请各位不啬赐教!!小弟感激不尽!
标准活塞发声器校准,频率为250Hz或1000Hz,声压级为94dB或124dB
校准话筒,主要是校准其基准灵敏度,前提是其频率特性已知且不会发生大的变化.因此,一般校准一个频率点的灵敏度就足够了.
精确的实验室话筒校准,需用标准消声室和互易校准方法,能校准整个频段.
因为声压跟温度和大气压力有关,所以需要测量温度和压力,哪个表就是气压表: barometer
A barometer supplied with the pistonphone gives the ambient pressure correction in dB, in the range 650 to 1080 hPa, provided it is checked annually to maintain its accuracy.
SATISFIED STANDARDS:
IEC 942 (1988) Class 1L (Class 0L with suitable external barometer)
ANSI S1.40-1984
NOMINAL SOUND PRESSURE LEVEL:
124 dB re 20 mPa ±0.2 dB at reference conditions:
Ambient Pressure: 1013 hPa
Ambient Temp.: 20 °C (68 °F)
Ambient Humidity: 65%RH
Effective Load Volume: 1.333 cm3
FREQUENCY:
Nominal: 250Hz
Actual: 102.4 Hz (ISO 266) or 251.2Hz ±0.1%
SPECIFIED MICROPHONE TYPES:
Brüel& Kjær (and similar types) 1², 1/2², 1/4² and
1/8² microphones (see calibration chart for more
details)
INDIVIDUAL CALIBRATION ACCURACY:
At Reference Conditions: ±0.09 dB
At Ambient Reference Conditions:
±0.12 dB with specified microphone types
Within Range of Ambient Conditions:
With External Barometer:
±0.15 dB — IEC942 (1988) Class 0L
With Included Barometer:
±0.30 dB — IEC942 (1988) Class 1L
NOMINAL EFFECTIVE COUPLER VOLUME:
19.733 cm3 (at 250Hz) including Nominal Effective
Load Volume 1.333 cm3
TOTAL HARMONIC DISTORTION: <3%
AMBIENT CONDITIONS:
Ranges:
Pressure: 650 hPa to 1080 hPa
Temperature: –10 to +50 °C (14 to 122 °F)
Relative Humidity: 5% RH to 95%RH
Required Measurement Accuracy:
Pressure: ±0.3% (IEC 942 Class 0L)
±2.0% (IEC 942 Class 1L)
Temperature: ±5 °C
Relative Humidity: ±15% above 35 °C (95 °F)
(measurement is not necessary below 35 °C(95 °F))
Power Supply
Batteries: 6 ´1.5 V IEC Type LR6 (“AA” size)
Lifetime: Typically 40 hours with alkaline batteries
(continuous operation at 20 °C)
Check: Constant check via “250 Hz” light
G.R.A.S的话筒是什么型号?
Low-noise Measuring System comprising:
½-inch (12.7 mm) Microphone:. . . . . . . .Type 40AH
½-inch (12.7 mm) Preamplifier: . . . . . . .Type 26HH
(with 3 m cable and LEMO FGA.1B.307 plug)
Frequency response:
12.5 Hz - 10 kHz: . . . . . . . . . . . . . . . . . . . . . ±1.0 dB
10 Hz - 16 kHz: . . . . . . . . . . . . . . . . . . . . . . . ±2.0 dB
6 Hz - 20 kHz: . . . . . . . . . . . . . . . . .+2.0 dB, –3.0 dB
Nominal sensitivity:
System: . . . . . . . . . . . . . . . . . . . . . . . . . . 800m V/Pa
Microphone: . . . . . . . . . . . . . . . . . . . . . . . 80 mV/Pa
Microphone polarization voltage:
200 V
Dynamic range:
Upper limit: . . . . . . . . . . . . . . . . . 113 dB re. 20 μPa
Lower limit: . . . . . . . . . . . . . . . . 6.5 dBA re. 20 μPa
这种话筒似乎精度不够!
谢谢,斑竹的解释,有些地方,还不明白.现在就不问了,明天上班自己先仔细琢磨,琢磨.明天我告诉你MIC是什么 型号!
mic型号是 TYPE 26AM!?和你说的好象有点区别! 另外兄弟能帮忙结束下IEC711标准的内容吗?
TYPE26XX是话筒前置放大器的型号,不是话筒型号
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