Lobby > Amp and DAC Measurements
iFi iDSD Nano Measurements
Marvey:
--- Quote from: madaboutaudio on August 31, 2015, 05:47:46 AM ---@oultrabaick:
iFi posted that AD5971 can't do 120db SNR due to glitching. Spurious-Free Dynamic Range
--- End quote ---
The glitching thing is overblown. Unless iFi has been working with the chip, they really wouldn't know the exact nature of the glitching. Sure there are data sheets, but only certain case scenarios are covered. Also, there are ways to greatly mitigate the glitching. I read a paper on the Internet on how to address this in a very elegant way and it turned out that Schiit did exactly this. The hint is in the architecture.
In terms of spurious-free dynamic range, a huge part of this is power supply.
Marvey:
There was some screwy behavior with this unit. I had to update the firmware before it even worked. Let me update it again and give it a try. I'll crank up the volume and use the diff probes and see what happens.
EDIT: Updated firmware. Redid all tests. The volume control works correctly with line out. Noise floor now looks right, revealing a few more things. Certainly much better looking measurements now.
Anaxilus:
Well, that's a bit better the utter disaster in the original graphs.
Marvey:
1) Early treble rolloff starting past 15kHz and -4db down at 20kHz. (graph #5)
2) -60db sidebands on IMD test. (#4)
3) Spikes in multiples of 60Hz below 1kHz @ 1dBr with rising noise floor as we go downwards in frequency. (#3)
4) Lots of junk in 19.1kHz test - out and inside of audio band.
Solderdude:
With the new FW ... does this change the subjective rating on the chart of awesomeness or does it still need to float ?
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