At our last gathering at a friend's house where we were measuring the Schiit Yggdrasil DAC, I was also asked to measure an Oppo BDP-105 player as a DAC. This player despite its age has a very positive reputation as far as fidelity. I made a complete set of measurements. I won't bore you with all of them as most were pretty good and competent until I landed on linearity test:
Yup, my jaws fell off. I repeated the measurement and still got the same. The cyan line is supposed to be the relationship between digital input and analog output. Normally it is a straight line until we get down to below -100 dB or even more. Yet here, even at the start of the test with full amplitude signal, we see clear steps in it. What it means is that the output changes proportional to input but then all of a sudden it gets stuck in a mud, refusing to change its output as we change input. The variations from zero error are shown in yellow which for an ideal line would be a flat line. Instead we have those triangles.
I put on the graph that it may be a stuck bit but I can't even explain it in that context. Clearly something is badly broken.
Looking at time domain with -90 dB we get this:
Here the sine waves look reasonable but they are shifted relative to each other. That is a larger error than I have ever seen measuring DACs.
In subjective listening I found the Oppo to sound muddy compared to my Topping DX7 that I had brought. I chalked to placebo as this was before the measurements. After the measurements I wonder if that observation was true.
Conclusions
There are people who are flippant about value of the measurements we make in the context of DACs. They think that it must be a walk in the park to achieve say, 16 bit accuracy. As we see here and in measurement of some other DACs, it is possible to screw up implementations of actual products. And that it is measurements like Linearity that bring an insight that is not visible in other measurements.
NOTE: it is possible this player was broken. I too have a BDP-105 (d) that I will test at some point.
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Yup, my jaws fell off. I repeated the measurement and still got the same. The cyan line is supposed to be the relationship between digital input and analog output. Normally it is a straight line until we get down to below -100 dB or even more. Yet here, even at the start of the test with full amplitude signal, we see clear steps in it. What it means is that the output changes proportional to input but then all of a sudden it gets stuck in a mud, refusing to change its output as we change input. The variations from zero error are shown in yellow which for an ideal line would be a flat line. Instead we have those triangles.
I put on the graph that it may be a stuck bit but I can't even explain it in that context. Clearly something is badly broken.
Looking at time domain with -90 dB we get this:
Here the sine waves look reasonable but they are shifted relative to each other. That is a larger error than I have ever seen measuring DACs.
In subjective listening I found the Oppo to sound muddy compared to my Topping DX7 that I had brought. I chalked to placebo as this was before the measurements. After the measurements I wonder if that observation was true.
Conclusions
There are people who are flippant about value of the measurements we make in the context of DACs. They think that it must be a walk in the park to achieve say, 16 bit accuracy. As we see here and in measurement of some other DACs, it is possible to screw up implementations of actual products. And that it is measurements like Linearity that bring an insight that is not visible in other measurements.
NOTE: it is possible this player was broken. I too have a BDP-105 (d) that I will test at some point.
----
If you like this review, please consider donating funds for these types of hardware purchase using Patreon (https://www.patreon.com/audiosciencereview), or upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).