Lake People MPA RS 01 User Manual - Gain Setting
13
GAIN SETTING
The input signal applied to the XLR terminal is fed to an extremely low-
noise integrated instrumentation amplifier.
Gain is set by the "GAIN"-rotary switch in 6dB steps from 0 to +66 dB.
The deviation from the indicated value is less than +/- 0.3 dB.
THE AMPLIFIER STAGE: THEORY AND PRACTICE
The MPA RS 01's gain is affected by a so called instrumentation
amplifier. It is represented by an IC specially designed for this task,
distinguishing itself by very low noise figures and a high gain/bandwidth
product.
When gain is set to +60 dB (x1000), the amount of noise added is only
approx. 2 dB more than the theoretically achievable minimum.
The gain/bandwidth product (GBW) and the slew rate are basically
responsible for the sonic quality of an amplifier. The higher they are, the
more transparent the sound becomes.
Slew rate is 10V/s, while the GBW is calculated from the frequency
response at a certain gain ratio.
The MPA RS 01's internal linear frequency response at +60 dB gain
exceeds 200 kHz. The resulting GBW is as high as 200 MHz (200.000
Hz x 1000).
PHASE REVERSE
In multiple microphone applications, inverting one or several
microphones´ phase can significantly improve the overall mix.
Reason therefore may be position-dependent time lags between
microphones or, in the worst case, an incorrectly soldered microphone
lead.
The "PHASE"-switch inverts signal polarity and is confirmed by the
yellow "REV"- LED.