CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Lobby => Amp and DAC Measurements => Topic started by: Marvey on September 02, 2015, 05:35:18 AM
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Schiit Modi 1 Measurements. This is a USB powered DAC. No help from weird. It sounds a bit on the lean and grainy side on some PCs. Depends upon quality of USB power. There measurements were taken on my PC instead of laptop. The PC is a bit noisier and has some spikes here and there compared to the laptop.
#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.
#8) 700 and 1700Hz two tone. Log x-axis.
Note:
- In graph #4, the -60db 1kHz signal actually has a cleaner spectrum than the -90db signal. I double checked this to make sure.
- In graph #3, the 1kHz signal will look fatter than usual. My PC won't process the FFT window past 32k points consistently unlike my laptop. This measurement is usually done with 131k points which results gives us better frequency resolution.
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Note:
- In graph #4, the -60db 1kHz signal actually has a cleaner spectrum than the -90db signal. I double checked this to make sure.
This is very interesting. Would love to see similar with the ODAC. I wonder if things get a little worse for some of these DACs as signal level decreases. Or if things (distortion levels) are consistent at different signal levels.
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I messed with different volumes measuring my VorzAMP Duo (from the PC) the other day. 100% PC volume, 99%, and 80%. Basically, the recommendations I've seen in the past from people.
100% has the best objective measurements, except on the Vorzuge amp, channel imbalance was highest at 100% and lowest at 80% (still less than 0.5dB different). That might be because of the amp itself, or it could be because of Windows. I plan on doing a similar test with a different amp (Liquid Carbon) after I get it.
http://www.basshead.club/measurements/vorzuge_vorzamp_duo/vol_comparison.html
Even sider note: I have a Schiit Wyrd now. I also have a loaner Dragonfly that measures like poop. This weekend I want to measure it with and without the Wyrd.
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Reason I thought mine was broken the other time was the IR inversion and weird looking Jtest spectra I was getting. Cool to see this Marv