The suggested preamplifier can be ordered only in few countries, then needs to be modified which includes SMD soldering. The authors say that no ready off-the-shelf preamplifier could be found. I would like to ask, what is so specific about the preamplifier? If it cannot be replaced by, say, this (one of many options):
then what is the exact reason? Noise level? In particular, is the signal inversion of the original amplifier important? If yes, it seems like something easily modifiable in software.
The suggested preamplifier can be ordered only in few countries, then needs to be modified which includes SMD soldering. The authors say that no ready off-the-shelf preamplifier could be found. I would like to ask, what is so specific about the preamplifier? If it cannot be replaced by, say, this (one of many options):
https://www.kemo-electronic.de/en/Light-Sound/Amplifier-Splitter/Modules/M237-Stereo-Preamplifier.php?faq 9 - 24 V/DC stabilized (or battery) | Current consumption: approx. 3.4 mA ± 20% at 12 V (without load) | Frequency range: approx. 8 Hz - 60 kHz, 3 dB at U out 1.5V RMS | Input impedance: 100k Ω | Output load: > 2k Ω | Amplification: approx. 30 dB ± 20% | Distortion: ≤ 0.02% ± 20%
then what is the exact reason? Noise level? In particular, is the signal inversion of the original amplifier important? If yes, it seems like something easily modifiable in software.