Measurements and Conclusion
Contents
We measured the ATC SCA2 preamplifier using the Prism dScope III. Power supply noise was measured using the Tekbox LISN and picoscope 5000-series. Common mode and differential mode noise was split with a Tekbox splitter.
The measurements show what we are actually already hearing: this is incredibly clean. The noise floor is particularly low with values just above -140dBFS. If we measure up to 96kHz we see that it rises slightly from 30 KHz onwards, but it does not exceed -125dBFS. Very neat. Grass we do not see. We do see a few small harmonics. But that should not really be an issue.
Response is practically straight. We see 0.2dB at 5 Hz and less than 1dB at 90 KHz: that is also pushing the limit of the Prism given the filters. Phase is neat with a maximum of 5 degrees at 90 KHz and -7 degrees at 5 Hz.
Power supply noise is well controlled. -104 dBu average at common mode noise. Differential mode is lower at -107 dBu. Common mode we see some grass around -82dBu. Differential mode is slightly quieter again at -87dBu. In both cases just very neat.