As you can see I finally got the second sample of the Pro Plus with promised improvements of measurements, especially in low frequencies. Time to find out what has changed.
I will use mostly the same gear as before. The biggest change is an introduction of the Cosmos Scaler, a buffer with variable gain to help get more precise results in stepped measurements. And to attenuate the impact of ESS hump for ADC Cosmos.
My methodology will differ a bit. This time I'm gonna use also DeltaWave software to investigate an impact of different interconnect cables as well as power sources.
At the moment just one graph to show distortions vs frequency for -3 dBFS sweep signal:
View attachment 2644
As both units behave very similar in many aspects (for example output voltage levels) I will focus on differences only.
Both units were powered by Allo Nirvana SMPS unless otherwise noted.
I suggest to look here for details on previous measurements of the first unit:
At a moment I can tell that my sample unit has an increased space around the coax socket. And a glossy finish of the chassis. Stay tuned :) Part 0 - a test gear possibly involved RME ADI-2 DAC FS, ESS edition miniDSP Flex, RCA edition E1DA Cosmos ADC, A grade PicoScope 4444 Intona 7055-D...
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FFT single measurements
Visible advantage in multitone measurement:
View attachment 2652
Reduced second harmonics level gives slightly better results with 1 kHz sine wave:
View attachment 2654
SINAD increases by 3 dB from 112.8 to 115.8. Dynamic range keeps the same level in range 118.8 - 119 dB.
As improvements are mainly for low frequencies, differences are clearly visible in the SMPTE test for IMD / low frequency distortions:
View attachment 2655
IMD reduced from -93,8 dB to -105.6 dB. TD+N reduced from -99.8 dB to -112 dB.
Stay tuned.