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Author Topic: iFi iDSD Nano Measurements  (Read 1939 times)

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Marvey

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iFi iDSD Nano Measurements
« on: August 31, 2015, 05:21:56 AM »
Measurements for iFi iDSD Nano. My opinion of the sound quality of this as a DAC or DAC/headamp are elsewhere. I set the volume to be within the the QA400's limits so the direct inputs of the QA400 could be used. The line outputs of the iFi were used, not the headamp outputs. The unit was acting funny so I updated the firmware. This time around, I used the differential probes on /10 and cranked up the volume all the way. The use of the probes increase the noise floor of the measuring equipment about 10db. 0dBr in the graphs was set represent the max output of the iFi. ARTA was used to generate the 16/44.1kHz signals from a PC to the iFi via USB and unfortunately DirectSound. Finally, my home is a noisy environment with lots of LED, CFB, dimmer, and Ethernet over A/C electronics. Right channel is displayed to get a sense of the limitations of the measurement equipment.
  • 1kHz @ -1dBr. The standard 1kHz measurement with the DAC running at almost max output.
  • 1kHz @ -90dBr. Low level signal @ 1kHz vs. noise floor.
  • 1kHz @ -1dBr. Same as above, but this time we are taking a close peak at the spectrum below 1kHz.
  • 19kHz + 20kHz. IMD. Slighter wider band view.
  • 19.1kHz. Wide band view.
  • 700 and 1700Hz two tone. Log x-axis.
  • massive multi-tone test.
  • PN white noise. Wide band view to note extension and nature of filter slope.
« Last Edit: September 07, 2015, 05:10:18 AM by Marvey »
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Marvey

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Re: iFi iDSD Nano Measurements
« Reply #1 on: August 31, 2015, 05:34:58 AM »
To be fair, this is a USB DAC. Getting power from USB is not necessarily the best way to go, but it does have portability advantages ("less wires" as my wife likes to say). Honestly, I thought something was totally wrong, until I checked the equipment really quickly with the Yggy and the Modi. I'll get Schiit Modi 1 (also a USB powered DAC) results tomorrow. The Modi 1 measurements are not great, but I already know they are not this undomesticated.
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Anaxilus

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Re: iFi iDSD Nano Measurements
« Reply #2 on: August 31, 2015, 05:40:41 AM »
Quote from: oultrabaick on August 31, 2015, 05:33:53 AM


I'd elaborate but apparently it was deleted on head-fi and the 'mentions' of a certain Analog Devices chip were redacted by the poster whose product is measured here.
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firev1

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Re: iFi iDSD Nano Measurements
« Reply #3 on: August 31, 2015, 05:42:34 AM »
But GO is awesome and is portable so no excuses really. Noise might be common mode crap if adc and dac share the same usb card/pc. Might not be the case with the Yggy due to awesome sauce usb but its an issue with usb powered DACs. I gave up on the Modi 1 because I thought I was measuring a broken device :X
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madaboutaudio

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Re: iFi iDSD Nano Measurements
« Reply #4 on: August 31, 2015, 05:47:46 AM »
@oultrabaick:

iFi posted that AD5971 can't do 120db SNR due to glitching. And that PCM1793 was superior to AD5971 in terms of Spurious-Free Dynamic Range.

Frenchbat pointed out atomicbob's Schiit Yggdrasil Measurement showed >120db and ask ifi for reply.

About less than one hour of Frenchbat's posting, Ifi's original post got [redacted] and no mention of AD5971 anymore.

this was the post that got redacted:
http://www.head-fi.org/t/702376/ifi-audio-pro-desktop-line-discussion-thread/720#post_11864881
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Marvey

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Re: iFi iDSD Nano Measurements
« Reply #5 on: August 31, 2015, 05:53:28 AM »
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

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.
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Marvey

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Re: iFi iDSD Nano Measurements
« Reply #6 on: August 31, 2015, 06:52:06 AM »
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.
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Anaxilus

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Re: iFi iDSD Nano Measurements
« Reply #7 on: August 31, 2015, 06:59:43 AM »
Well, that's a bit better the utter disaster in the original graphs.
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"If you do not change direction, you may end up where you are heading." - Lao Tzu

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Marvey

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Re: iFi iDSD Nano Measurements
« Reply #8 on: August 31, 2015, 07:06:58 AM »

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.
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Solderdude

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Re: iFi iDSD Nano Measurements
« Reply #9 on: August 31, 2015, 07:11:34 AM »
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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