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Posts by stv014

 The paper uses 120 dB SPL as the reference (0 dBFS) level, which is probably quite a bit (>= 10 dB) higher than it was in your test, and the "noise inherent in PCM audio" was assumed to be simple triangular PDF dither, that produces the most audible noise. For comparison, here is a frequency analysis of your Audacity test sample (green), the simple white spectrum +/-1 LSB TPDF dither (blue), and a slightly better "shaped" TPDF dither (red) where the triangular noise is...
Well, being able to hear noise at ~5 dBA SPL - and even less under 10-12 kHz because of the noise shaping - might still be possible (although for most people under normal conditions, 10 dB is already "silent"), but I wonder if there were possibly any problems with the playback.
 The advantage of a filter with a gentler slope is actually that it reduces ringing, in addition to being cheaper to calculate. A filter with a steep roll-off still removes aliasing as long as its response falls low enough by the Nyquist frequency. Also, a non-integer resample ratio does not necessarily imply worse quality by any practically significant amount, it just makes the processing computationally more expensive. This can be seen in these tests, where resampling...
Regarding the test above, note that Audacity uses buggy noise shaping by default when exporting 16-bit stereo files. This problem does not affect mono files (like the above "30 seconds of silence" sample), where the noise shaping does work correctly, but the default stereo 16-bit output from Audacity has an ENOB of only about 13-14. The bug may or may not have been fixed already (I do not normally use Audacity, so I do not check it regularly), but I know it definitely...
 This is most likely an Audio DiffMaker problem, when comparing the recorded audio to the original, there is a relatively large ~75 ppm pitch error, which confuses the program, and it does not extract the difference correctly. Also, correction for sample rate drift needs to be enabled in the settings, but even if it is, it is not measured accurately, as DiffMaker only finds about a tenth of the real value. With some manual correction of delay, pitch, and amplitude...
 You could measure the frequency response on the output of both ODACs, and possibly also on the amplifiers, and on the ODAC outputs loaded with the amplifier. Maybe you have an ODAC that is defective in some way.
 For a test with both acoustic and electrical measurements, check my link from a few posts ago. While these were not made with as expensive equipment as the Benchmark one, they do show that the acoustic distortion increases approximately by the same amount that is measured on the voltage input to the drivers. Of course, it is not "100 times worse distortion" then, like in the Benchmark article, but more like ~2 dB at the resonance frequency, at least with the headphone and...
 In any case, you need to measure the voltage on the speakers or headphones. This may require DIY cables or connectors, if you do not have a connector (like the splitter recommended for headphones) that makes it possible to access the terminals with a multimeter.  Not necessarily if at least one of your speaker amplifiers or receivers has a balance control. Then you can adjust it to match the imbalance of the other device. Another solution that may work is to use different...
 Well, it would first have to be proven that the Galaxy really sounds different because of the output impedance, and not one of many other possible reasons. If the output impedance is indeed the problem, then it should be possible to reproduce the same effect by adding serial resistors to the Clip Zip. It should be possible to measure the effects (if any) of the output impedance on the headphones. As for example these tests show, the frequency response errors and...
I do not have a YouTube video, but for measuring the voltage on headphones, if you do not want to solder, you need: - a digital multimeter that is capable of measuring AC voltage, and is at least somewhat usable at ~1 kHz (it is not a problem if it e.g. only shows half voltage at that frequency, as long as it does so consistently) - a splitter with one female and two male TRS connectors, like this one You should then use the splitter as an extension cord (headphones to...
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