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Request: Measurement standardization

junki

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Mar 24, 2018
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Hi,

After coming across this community for a few days now and appreciating the measurements, I noticed that rarely is a full set of measurements made (or at least shared) before conclusions, and more times than not only a subset of measurements are made.

If possible, I'd like to request some standardization of official "review and measurement of <device>". In particular, the following suggestions:

For official reviews of devices, include the following set for USB (if applicable) and S/PDIF separately:
  • Frequency response & channel matching
  • Jitter and noise
  • Amplitude-domain linearity at 16-bits & 24-bits
  • Time-domain linearity at 16-bits & 24-bits
  • Frequency domain THD+N with THD% and THD+N% displayed
  • IMD
  • HD and Noise of 1Khz tone at 0 dB
Ideally, all these charts have the same zoom, scale, settings from review to review, which I see is sometimes not the case from one device review to another.

This will let us 1) get a full picture of each device and 2) more easily make apples to apples comparisons.
 

amirm

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Hi. We have had a recent thread on this. And it is a goal to achieve.

Unfortunately, there is a hard limitation in my measurement set that doesn't allow equal set of graphs be presented for all DACs. Specifically, when a DAC S/PDIF input, my analyzer can be in control and perform synchronous measurements. For example, it can iterate level or frequency and measure distortion parameters. On lower cost DACs which only have USB input, clearly this does not work as the file has to play in the computer. The newer version of the analyzer can do that but requires ASIO drivers which I am not fond of using as not every device as ASIO drivers.

I have ported some of the measurements to USB domain and am refining them to be closer match to S/PDIF ones. It is a work in progress and unfortunately a semi-manual one so mistakes can happen. In some cases like linearity I have to take the data to Excel to graph so the presentation can't even be the same in all cases.

Believe it or not, I do a lot to keep the measurements the same but don't always catch everything in the pressure of trying to present the data sooner than later. Also, sometimes I need to emphasize something that is important in a review and not other, by zooming or changing scales. I had to do that for tube amps and review of Audio-gd as they produced more distortion than normal. I also introduce new useful tests from time to time. This has happened recently as compared to a year ago where I fewer tests.

You can help me get there by pointing out differences that you see and I can correct, re-measure.
 
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Blumlein 88

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I hear you, and this has been discussed a little bit. I like having a full spectrum of measurements to pour over the results. Amir's thought is to keep things as simple as possible so reader's eyes don't glaze over and they get nothing out of it. For a general forum I think he has the right idea.

Also it probably isn't necessary to list every single measurement if it shows nothing interesting. I mean how many completely flat to 20 khz frequency response graphs do I need to see?

EDIT: well Amir posted at the same time I did so you have his direct answer.
 

Speedskater

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Specifically, when a DAC has USB, my analyzer can be in control and perform synchronous measurements. .......................
On lower cost DACs which only have USB output, clearly this does not work as the file has to play in the computer.
Is this a typo?
 

restorer-john

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To Amir's credit, his tests are well presented and cover much of what is considered important.

There's always some test I'd like to see, but that's just me, wishing I had the AP on my bench. :)
 
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