BLIND TEST INVITE: Do digital audio players sound different?

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Looks reasonable at first glance and since you are including Cécile McLorin Salvant as a test, the process might be enjoyable.

 

Question: how have you validated this as a test procedure? Its not immediately obvious to me that this works as a test procedure -- it might but I'm not sure -- might be valid in certain cases but not others etc etc

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12 minutes ago, Archimago said:

?What validation are we looking for in this experiment?

 

The same validation that anyone would want with any experiment particularly when using a new measurement technique ... but specifically: are the SQ differences in the recordings, the same as they would be with the device in my home? 

 

The certainly might be, particularly if the changes are dramatic, but (not knowing the details) I can think of a bunch of reasons that 24/96 wouldn’t capture small differences in devices. My back of the hand rule of thumb is that I want my measuring device to have 10x the resolution of the difference I am trying to measure...

 

That said, the ADC you’ve selected looks very reasonable and a good choice.

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1 hour ago, pkane2001 said:

 

Jussi, is that really important? If there is a 1MHz signal at -100dB, how is this going to affect any normal audio system? And even if it does through IM or through another mechanism, wouldn’t the ADC that Arch is using capture anything that is reflected into the audible range with plenty of margin? While it may be interesting to see the MHz range effects of a DAC as a curiosity, why is this significant for this particular test?

 

You tell me, I mean mathematically 24/96 doesn’t capture everything (and we can go into this in much more detail there’s really no question about this) ...

 

So tell me, how is this validated? How have you determined what is enough? No tell me, how have you determined what “enough margin” is? ... this is actually a very common mistake and I can tell you that in my area of expertise : digital imaging, this mistake is made all the time : look up “sub pixel” imaging/resolution etc to get a hint at some of the math ...

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16 hours ago, pkane2001 said:

Well, you tell me. If the point of the test it to determine the audibility of some process, is it enough to measure just the audible range, or must I measure everything up to the GHz range and above? If there is some distortion well above audible frequencies and it doesn't get reflected in the audible range, why should I care?

 

(btw, I don't need to look up sub pixel resolution, I've been coding image processing algorithms for about 30 some years, everything from resampling to filters in frequency domain, to feature extraction, PSF analysis, reconstruction and deconvolution )

 

My answer is : no it isn't "enough" to measure the audible range... if that were the case then why not just measure 16/44? ... answer that for yourself, and start from there ... in any case a validation process might indeed sweep into the Mhz or Ghz range to see if that might have an effect (e.g. IMD), rather than simply assuming.

 

In any case I'm not saying that the testing procedure is incapable of demonstrating differences, rather I was asking if the testing procedure had been validated ... it doesn't seem to be, and this is intended to capture large differences, and of course large differences in the audible range would be expected to have the biggest SQ difference, and might be totally fine for the purposes here ...

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1 minute ago, esldude said:

So ghz has to be taken into account.  Or megahertz.  

 

 

Well I once had a jfet which worked fine in a circuit (and sounded great) and later I built another and lo and behold it came from a different plant, and was oscillating way up in the upper Mhz region, too high for my oscilloscope at the time to measure, and it sounded like sh*t, and when I remeasured it with a Ghz scope I saw the problem ...

 

Does this always happen: no! can it happen: yes!

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1 minute ago, esldude said:

And did it effect the 20 khz band results while it was oscillating?  In other words was it causing distortion or IMD products to show up in your conventional audio band tests?

 

Um, a gate stopper fixed it ... we could speculate. My point is that, essentially in every field, if you don't look for stuff, you won't find stuff.*

 

* to paraphrase Kuhn

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16 hours ago, bibo01 said:

Why do you think this technology is not more widely implemented in hi-fi systems?

It’s the future. 

 

At 45 MHz you can build a wireless transmitter and then the DAC/amplifier/speaker can broadcast your music across the whole town 😂

 

The only problem is that some aircraft communications systems use that frequency band, otherwise ... nothing a little strategically placed mu-metal can’t fix  

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4 minutes ago, Miska said:

 

Of course you have output filter like with analog class-D too. Higher the frequency, easier it is to remove it with simple filter without effects near audio band...

 

Yes!

 

This type of design interests me quite a bit. The issue is controlling transmitted EMI from before the filter!

 

Doable but not entirely trivial.

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11 minutes ago, psjug said:

The Zetex/CSR/Qualcomm DDFA technology is in a fair number of products.  Seems to be mostly toward the budget end - stuff made by NAD, Bluesound, Denon, and now Sonos.

 

All of the Class-D type amplifiers use a feedback loop, analog for Class D or digital for DDFA, but consider a DAC itself: there is no such feedback loop prior to the I-V stage. Our DACs prove that it’s entirely possible to produce a low distortion current amplifier with zero feedback