Topping D900 DAC Review

[nanook]

It also means that if the SMPS fails it can be replaced easily and cheaply.

That's one of the the key points for me. I rather have a standard USB wall-wart and some DC/DC converters in the unit.
There are a couple of tiny DC/DC converters making 3.3V, 1.8V etc. locally anyways. So why not generate the +/-12V (or +/-15V) for the I/V-stage and output stages inside the unit as well. We're talking about a few 10mA only.

The WiiM Pro (Plus) follows this concept. The only power supply is a decent quality USB Wall-wart.

Many units having the PS internally have the audio ground connected to PE (for safety reasons I guess) - another chance to build a ground-loop and experience hum.

 

[Chanur]

That's actually the most important aspect when using AI. Never ask a question that is suggesting something - the AI will rarely contradict but rather start "pleasing" and follow the direction that you were suggesting in your prompt.
I'm wondering why this habit of the AI still exists. Probably because it costs more resources to give a contradictory answer with a good reasoning.

It's because it's engineered to do that. The AI models that don't provide the answers the developers want get destroyed.

 

[ObjectiveSubjectivist]

I assume they had to code their own filtering, then why not doing something like Chord is doing.
We still got "lazy" filter.

 

[taner]

Your information seems a bit outdated, at least 1-2 decades.
I work and develop primarily in industry, where we use clock generators with ppb accuracy, not ppm. None of these devices use TCXOs. However, I built my own 10 MHz OCXO clock with square wave output 10 years ago, which is still more accurate than any TCXO.

TCXOs are simply an inexpensive way to achieve a relatively temperature-independent and accurate clock signal. With an accuracy of 1-1.5 ppm, they cost around €3 each, and at 0.5 ppm, €10-18 each.
But it's been possible to do much better for a long time.

Are you sure what you are talking about? If you are such an "industrial" person you should aware of that the thing about the TCXO is their utterly low phase noise, even in low frequencies. Not the PPB level accuracy. I yet to see a regular clcok circuit that can be matched to the phase noise performance of the industrial grade TCXO's. I would like to see your clock circuit's phase noise graph. Can you share?

 

[antcollinet]

Are you sure what you are talking about? If you are such an "industrial" person you should aware of that the thing about the TCXO is their utterly low phase noise, even in low frequencies. Not the PPB level accuracy. I yet to see a regular clcok circuit that can be matched to the phase noise performance of the industrial grade TCXO's. I would like to see your clock circuit's phase noise graph. Can you share?

Regardless of that comparison - are you aware of just how bad jitter needs to be in digital audio in order to cause audible distortion?

Jitter has not been an issue in DACs for decades - if ever.

 

[taner]

Regardless of that comparison - are you aware of just how bad jitter needs to be in digital audio in order to cause audible distortion?

Jitter has not been an issue in DACs for decades - if ever.

Yeah, I know I know.. If you're happy with your -120dB or lower jitter DAC, no question... stay with it. But the situation can be different for the people who is aware of what is missing in what they are hearing. This is like trying to explain the existence of the God-given "soul" in scientific terms to the people with no belief.

 

[nanook]

But the situation can be different for the people who is aware of what is missing in what they are hearing.

Are we in the domain of "golden ears" and "blinded listening sessions are unnecessary because I can hear the difference clearly" again?

I can appreciate the discussion from a measurement point of view - I've been hunting down issues that are interesting from a scientific standpoint or relevant for the sake of measurement capability - from the point of audability a well engineered 90€ DAC is way beyond human hearing.

 

[RandomEar]

Yeah, I know I know.. If you're happy with your -120dB or lower jitter DAC, no question... stay with it. But the situation can be different for the people who is aware of what is missing in what they are hearing. This is like trying to explain the existence of the God-given "soul" in scientific terms to the people with no belief.

Just test it yourself instead of imagining it. Jitter at the levels we're talking about in even half-competent DACs is not audible. It's orders of magnitude away from that. I have never seen a practical example of jitter which you could actually hear. Before that happens, the DPLL in your DAC will give up and you get drop-outs.

 

[antcollinet]

This is like trying to explain the existence of the God-given "soul" in scientific terms to the people with no belief.

Indeed. I find I am surprised by your degree of self awareness.


Equally - you could say it is like flat earthers trying.....

Well, I'm sure you get my point.

 

[nanook]

Having some psychoacoustic background I'm quite convinced it needs a lot(!) of jitter to get audible.

DEM (Dynamic Element Matching) is a technique to achieve the distortion figures we are used to see in quality measurements.
Might it eventually become audible?

For those of you who are interested:
'DEM (Dynamic Element Matching) - might it be audible?' https://www.audiosciencereview.com/...c-element-matching-might-it-be-audible.71285/

 

[taner]

Just test it yourself instead of imagining it. Jitter at the levels we're talking about in even half-competent DACs is not audible. It's orders of magnitude away from that. I have never seen a practical example of jitter which you could actually hear. Before that happens, the DPLL in your DAC will give up and you get drop-outs.

Who said it I didn't test it for myself? Because you are imagined it like that, right? You are the one who actually imaging the things because you are seeing me just like the way you are imaging me in your head...

 

[RandomEar]

Who said it I didn't test it for myself? Because you are imagined it like that, right? You are the one who actually imaging the things because you are seeing me just like the way you are imaging me in your head...

Sure. Can you name a single DAC with audible jitter issues?

 

[taner]

Indeed. I find I am surprised by your degree of self awareness.
Equally - you could say it is like flat earthers trying.....
Well, I'm sure you get my point.

You think that you're the only smart person around? If a flat earther had a chance for SEEING the Earth from outer space with own eyes, you could rightfully argue for his/her denial. But I'm rightfully confirming what I'm HEARING, right? So, what is wrong with this? Doesn't this fit your "scientific" jargon?

 

[taner]

Sure. Can you name a single DAC with audible jitter issues?

So you just begin to value the arguments of someone who "imaging" the things in his head? Come on.. hold up! you were doing good...

 

[RandomEar]

So you just begin to value the arguments of someone who "imaging" the things in his head? Come on.. hold up! you were doing good...

I'll take that as an "I can't". Thank you and good night.

 

[antcollinet]

But I'm rightfully confirming what I'm HEARING, right?

replace the word hearing, with perceiving - and with your perceptions subject to all the biases that apply to all humans, then ... right.

And no - i am not saying you are imagining it - alterations cause by the pre-processing of the unconscious brain are not "imaginations". It literally changes the content of the sound before your conscious brain gets it.

 

[VientoB]

I assume they had to code their own filtering, then why not doing something like Chord is doing.
We still got "lazy" filter.

With AI now it must be really easy to replicate what Chord is doing?

 

[ObjectiveSubjectivist]

With AI now it must be really easy to replicate what Chord is doing?

Not sure why we should use AI for such basic thing as implementing step filter.

 

[nanook]

replace the word hearing, with perceiving - and with your perceptions subject to all the biases that apply to all humans, then ... right.

And no - i am not saying you are imagining it - alterations cause by the pre-processing of the unconscious brain are not "imaginations". It literally changes the content of the sound before your conscious brain gets it.

Very precise to the point - in just two sentences. Thank you for this minimalistic summary !

 

[antcollinet]

With AI now it must be really easy to replicate what Chord is doing.

Not sure why we should use AI for such basic thing as implementing step filter.

Also, I believe chord is using quite heavy hardware resources to implement their un-necessarily complex filter. (Complex programmable gate array).

Also not sure why you (@VientoB) are calling it lazy. It is a perfectly adequate filter.