Suggestion for reviews: Extend the frequency range for 'THD+N vs Freq.' test

[nick_l44.1]

If there is a problem with a specific DAC, then it does NOT call for adding a test to every DAC. Half the time you all are arguing this, and half the time you seem to claim this is a universal need. Make your mind and be clear with your justifications and arguments.

Well, yes. That's reasonable. However, it's not entirely correct to give recommendations without at least mentioning whether the DUT has such known problems. I understand perfectly well that measuring detailed characteristics takes a lot of time, but you are right that the same problem does not need to be described in detail every time; a brief conclusion based on a quick, unpublished check will suffice.
I suggest looking at the TDFD Bass IMD test (41 Hz & 89 Hz 1:1). Not in terms of including this test in the standard measurement package, but using it to detect problems. It is also indicative of the fact that in a very important section [-38 dBFS, -14.5 dBFS], not only IMD but also noise are greatly increased.

 

[tccalvin]

Nevermind then. I get the message. Being critical of the main review system = insulting or threatening Amir. Cool.

I'm not interested in providing feedback any longer.

I suggest looking at the TTFD Bass IMD test (41 Hz & 89 Hz 1:1). Not in terms of including this test in the standard measurement package, but using it to detect problems. It is also indicative of the fact that in a very important section [-38 dBFS, -14.5 dBFS], not only IMD but also noise are greatly increased.

Let me save you some time. The answer will be "no".

 

[nick_l44.1]

Let me save you some time. The answer will be "no".

In any case, it's not up to me to decide. The amount of work involved could actually be enormous. I simply pointed out that sometimes such serious problems can be overlooked due to the physical impossibility of performing all possible checks every time under all possible conditions for all combinations of inputs and outputs.

 

[pablolie]

Nevermind then. I get the message. Being critical of the main review system = insulting or threatening Amir. Cool.

Wasn't just Amir. Many participants have questioned you on why you think ultra and infra is of such vital importance, and you have never made a convincing point... and in response you just try to bully through the skepticism of many experts in here.

Lesson: Make a better argument. But clearly you aren't learning. You discredit yourself with every petulant rersponse. And calling someone offering a perfectly valid and fact based argument "dishonest" is NOT merely "criticism".

 

[kyuu]

I'm not inclined to deal with the poster's temper tantrum, so my last input will be this: if you really believe this is of vital importance, then maybe consider putting in the work and doing it yourself. We are never down on anyone who volunteers their time and expertise to give us measurements. If you actually find endemic issues among DACs that aren't being caught under the current testing regime, I at least will happily eat crow.

 

[oleg87]

CS chips are not a "specific DAC", they are used across a large number of popular products.
More importantly, there's clearly a gap in the test panel by which "clever" optimizations systematically create audible artifacts that elude measurement, neither hypothetically nor purely with some contrived stimulus. Amir is obviously free to spend his time as he sees fit, but the general resistance to even the idea of closing this gap is bizarre to me. If -95dB distortion products in a DAC are apparently a serious enough issue to earn a product ASR's disrecommendation, it's hard for me to square the rationale that this isn't also a meaningful issue.

 

[BeerBear]

For what? Finding whatever is the issue is with CS DACs? Or in general?

Both. I already said that it's for both.
I brought up the dongles' behavior, because it's something I experienced first hand. But I believe there are other potential uses for it.
I think @kemmler3D made a valid argument that even regular harmonic distortion under 20Hz could have audible consequences, for example. I don't see how that or even ultrasonic induced issues can be just ruled out entirely.

Adding more tests is very onerous when multiplied across every product I test.

I understand. But I didn't ask for more tests, just for slightly changing the existing one, which literally takes a few seconds. Ok, a few minutes if you want to check that the test works as intended.

As for adding new tests in general: I think as long as there are audible issues that slip through, we can't be satisfied. So in that case even asking for new tests would be perfectly justified and expected. But I'll let others propose and argue for new tests, this one is just about extending the frequency range.

To be clear, there is no case whatsoever for testing products at 5 Hz.

What about the evidence that I provided in relation to the Apple/CS dongles? When such a test points to obvious flaws, how is it not a valid use case?

IMO a proper review should at the very least spot humanly audible problems that happen under normal circumstances. That's the baseline. And hopefully it would go even beyond that and also cover any potential (inaudible) "safety margin" that a device might have.
If you truly think that audible artifacts (such as those that these dongles produce) are "insignificant", then I'll never bother you with anything like this again. Like, no hard feelings, you have your own standards of "good quality" and I have mine. But that's definitely inconsistent with your previously stated standards, which is why I'm surprised by such a dismissive attitude.


Back on the main topic:
Let me be clear that this suggestion of course applies to anyone who's testing stuff and doing THD+N frequency sweeps. The 20-20kHz range is still the default/standard, but I can't see a rational reason for it being so. If anyone believes that limiting the range that way produces better test results (as in: more accurate assessment of a device), let me know why please. I suspect that it's just a case of "that how it's usually done", but you never know.

 

[kemmler3D]

I think the discussion has become too heated for the substance of the topic here...

OP provides an example of a DAC that produces audible (>20hz) artifacts with high level subsonic input.

I think it's reasonable to suggest that THD sweeps should start at a lower frequency so we can catch these DACs.

Even though subsonic content in recorded music isn't very common, it's not rare either. Any recording of drums that isn't highpassed will have some, maybe a lot.

I haven't used Amir's test setup so I don't know how much extra work this entails. But I would personally find measurements of subsonic distortion interesting / useful.

As for measurements of ultrasonics and ISOs I'm not nearly as convinced they would help separate the wheat from the chaff.

 

[Sebby]

As far as the DRE artifacts are concerned, I would propose the 32-tone multitone level sweep test and the CMaj test used here.

These tests should really be standard in reviews going forward, so that we can avoid situations like the FiiO KA11 review, where the dongle got a "Great (golfing panther)" score even though it really shouldn't have, given what we now know.

Continuing with the usual 0dBFS 1kHz sine and multitone puts us in the territory of "lying by omission" and that's really not okay.

That's not to say that the CS dongles are bad or unlistenable, but presenting them as SoTA DACs when they're clearly not is another story.

Wait! I also have the KA11 in addition to the iBasso DC07 PRO, Tempotec Sonata BHD, etc... The DC07 has this issue and it’s perfectly audible.
The KA11 doesn’t have that problem and sounds clean, like a Topping G5 or almost.