CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Lobby => Amp and DAC Measurements => Topic started by: Marvey on August 31, 2015, 03:51:06 AM
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There measurements were done on the QA400 with the QA190 differential probes. The balanced outputs of the Yggy were used. Since the Yggy's outputs are so hot, the differential probes were put on /10. 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 Yggdrasil. ARTA was used to generate the 16/44.1kHz signals from a PC to the Yggy via USB and unfortunately DirectSound. At a later date, I'll make WAV files to playback directly via WASAPI in JRiver. 16384 points were used for most of the FFTs. A noise lower floor could have been obtained with a larger window, but processing would have taken longer and I didn't want to wait. 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.
A lot of these measurements are comparable to those seen in Stereophile with the exception that the AP gear used by JA is better. These measurements supplement the ones taken by atomicbob here: http://www.changstar.com/index.php/topic,2405.msg66591.html#msg66591 (http://www.changstar.com/index.php/topic,2405.msg66591.html#msg66591)
#1) 1kHz @ -90dBr. Low level signal @ 1kHz vs. noise floor.
#2) 1kHz @ -1dBr. The standard 1kHz measurement with the DAC running at almost max output.
#3) 1kHz @ -1dBr. Same as above, but this time we are taking a close peak at the spectrum below 1kHz.
#4) 19kHz + 20kHz. IMD. Slighter wider band view.
#5) PN white noise. Wide band view to note extension and nature of filter slope.
#6) 1kHz @ -60dBr. Mid level signal.
#7) 19.1kHz. Wide band view.
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Would love to see how this fairs against the ODAC rev B. Will ship Mike's tomorrow.
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The point of the 19-20kHz IMD plot is to show how large the 1kHz IMD product is.
As the plot is now it stops at 5kHz so doesn't show what the plot is all about.
Of course the sidebands are also interesting ...
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The point of the 19-20kHz IMD plot is to show how large the 1kHz IMD product is.
As the plot is now it stops at 5kHz so doesn't show what the plot is all about.
Of course the sidebands are also interesting ...
It goes all the way down to 0Hz, not 5kHz. Look closer. These are all linear scale. Easier to look for certain things.
Anyways, I thought these would be interesting to post since I was told there was some drama on HF regarding Yggy specs which were of course deleted by the mods there. That means I am going to investigate.
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When is the Gumby gonna get measured? ahoy
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It goes all the way down to 0Hz, not 5kHz. Look closer. These are all linear scale. Easier to look for certain things.
Anyways, I thought these would be interesting to post since I was told there was some drama on HF regarding Yggy specs which were of course deleted by the mods there. That means I am going to investigate.
Ah sorry ... missed that.
Linear scale is indeed more revealing here !
Looks good, no 1kHz at all or at least below the noise floor of the ADC/probe thingy
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Anyways, I thought these would be interesting to post since I was told there was some drama on HF regarding Yggy specs which were of course deleted by the mods there. That means I am going to investigate.
Interesting of course. The more measurements we have, the better. As to the drama, the iFi guy was talking out of his ass, he got served, and pissed his pants. He looks like an ass here now, but of course it's ok on hf, as noone will ever know. Not really as interesting as these measurements anyway.
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Interesting of course. The more measurements we have, the better. As to the drama, the iFi guy was talking out of his ass, he got served, and pissed his pants. He looks like an ass here now, but of course it's ok on hf, as noone will ever know. Not really as interesting as these measurements anyway.
did you managed to screenshot or save the ifi's full post?
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I don't keep track, have bigger fish to fry.
But the main claim was that Yggy's chip were not able to do better than 120dB of SNR, and that all said and done, it was lower than that. I simply pointed out the measurements of AtomicBob that show 121.xdB, and he probably realized that he was in deeper waters than he thought.