AudioControl MP-200, Руководство пользователя

Страница: 12 / 14

MP-200 Operation Manual
Appendix
Gain versus Amplification
A common term on preamplifiers that can cause some confusion is Gain. You need to make certain when
you are calculating signal levels through the MP-200 preamplifier whether your analyzer is requesting
Decibels of amplification or the actual Gain factor. Decibels represent a logarithmic ratio of the input
signal to the output signal of the preamp. Gain is a mathematical multiplier of the input signal to the output
signal.
For you technogeeks in the crowd, multiple stages of gain and decibels combine in very different ways...
Gain Factors multiply when stacked in series: 3.16 + 10 = 31.6 X Gain
Decibels add when put in series: 10 dB + 20 dB = 30 dB
Converting dB (Amplification) to Gain (Multiplier)
Mic Gain (dB) Gain
0 dB 0
10 dB 3.16
20 dB 10
30 dB 31.62
40 dB 100
An Example:
The CM-10 microphone has a nominal output voltage of 24.5 mV at 94 dB acoustic sound pressure level.
With the MP-200 set to 20 dB, the output voltage from the preamp will be 245 mV.
20dB Amplification = 10X Gain Multiplier
24.5 mV Input x 10 = 245 mV Output
CM-10 Measurement Microphone
The CM-10 is a very accurate measurement microphone. To further increase the accuracy of acoustic
measurements, many audio analysis software packages use a microphone data file. Use these compensation
points to create your system’s data file.
Typical Frequency Response of CM-10 Microphone
CM-10 response calibration file data
+1.5 dB 20 Hz
+0.5 dB 100 Hz
-1.5 dB 8 kHz
+2.0 dB 20 kHz