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Posts by stv014

 Sorry, I am not familiar enough with iPods to have guessed from the "iPod 15 GB" that it can only be an iPod 3G. If that is the case, this article seems to confirm the capacitor coupled output (-3 dB at about 50 Hz with 25 ohms load impedance).  It is not really the amplifier "running out of juice", since the effect is (other than for the capacitor having non-ideal characteristics in practice) linear, and independent of the output level, unlike clipping. The amplifier...
 The article does not tell exactly what version of the iPod it is, but at least some older models had capacitor coupled headphone outputs that caused audible bass roll-off with low frequency loads, such as typical portable headphones and ear buds. That produces a square wave response like what is seen in the article. I think both graphs shown there may also have clipping in the analyzer or ADC, rather than from the iPod itself, because a square wave response that starts...
 Undithered quantization adds non-linear distortion, which can be subjectively perceived as different effects depending on what the input is. If the input is complex enough and has a high entropy, then the error can still end up being noise even without dithering. But with a low level and/or pure tonal signal, the distortion products (which are similar to those of crossover distortion in that they can be high order and not decrease with lower input level, so it is...
 With the number of tests you did (I guess it is a total of hundreds of trials by now), getting occasional <0.05 p-values over short sections of long runs can easily happen by chance. And a 7/7 score at the beginning of a long run makes the entire rest of it look better. For example, without the first 4 trials, test192 would randomly vary between 12.5% (3/3) and 50% over the remaining 28 trials, with an overall score of 28.6% chance of guessing. When a 5/5 or 7/7 run does...
 Because CD quality audio has a bit rate of 44100*16 = 705600 bps / channel, and with 1-bit encoding, that is the theoretical minimum that is required to avoid loss of information. Additionally, SACD is more comparable to 96 kHz/18-20 bit PCM, so it is already about 1.8 Mbps of information per channel. Encoding it as a noise shaped 1-bit stream is not perfectly efficient either, which increases the required sample rate to a few MHz in practice. 96/24 format PCM has a bit...
 Well, a theory that "proves" that their 2.8224 MHz/1-bit SACDs have only 6-bit audio resolution (comparable to AM radio) is definitely something to be worried about.
 This would only be the case with a very naive and sub-optimal design that basically outputs a simple pulse width modulated square wave, as I guess the figure of 3 GHz comes from multiplying 44100 Hz by 65535. This is analogous to halftone dither in image processing, whereas noise shaping is more like error diffusion (e.g. Floyd-Steinberg) dither, which is more efficient at the same resolution (see these example pictures). By the way, even then 3 GHz would not be correct,...
Not sure if Sound Science is the best forum to create this thread at, given that most replies here will probably not agree with your post. In any case, oversampling delta-sigma converters are capable of reproducing CD quality audio and better. It is not a new technology now, and has been well tested over the years. The reason why R2R is disappearing is not just cost cutting, delta-sigma actually performs better if properly designed and implemented, while still being cheap.
 Or, to put it more simply, with a given load and power supply, one will not be able to output more power to the load by adding serial resistance*. That should be easy enough to see. With an amplifier that has very low measured output impedance, matching it with the load does not necessarily give the maximum power output, even if overheating issues are ignored. In fact, it is rather unlikely with typical amplifiers because of current limiting and much higher open loop...
The test was not done on Windows, so these settings were not available. As far as I know, unlike the Xonar DG, the Xonar D1 does not have hardware support for switching between headphone and 2-speaker mode, the difference is only in the DSP (Dolby Headphone etc.) in the Windows driver.
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