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Review and Measurements of Wyred4Sound DAC-2v2 SE DAC

finneybear

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When nothing is playing, maybe. With the presence of a signal there is quantization noise, with 24 bits playing -144dB down is best case scenario.

Nope. You are confused by what a FFT chart means. The noise floor here is the FFT floor. It is the frequency components of the original noise. In other words, you have to add all these up for the real noise floor.

Machines like AP use ADC to convert signal to digital data before going to FFT. The conversion errors have a big impact on the accuracy for low level frequency components hence the FFT gain people are talking about. Then there are a lot of DSP stuff involved which is way beyond the scope of discussion here.
 

finneybear

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Perhaps I misunderstood. I thought you said -150dB is what's coming from the DAC.

Then I will have to apologize for this. For doing measurements, we usually look at a FFT and call it the noise floor. Yes, actually it is not.
 

Blumlein 88

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So here is the TDA1547 inside a professional Yamaha D2X:

View attachment 21144

And here is the famous TDA1541, note the test date is back to year 2009:

View attachment 21146

My God! The 2nd harmony is already -50db! So based on your FFT gain thesis, what is the real noise floor for this TDA1541?

There are people pushing the performance envelope, OK? It's similar to the situation Mola Mola is running into with the current AP. It's already beyond what AP can do. And they have to figure out a solution.
Well this might impress those who don't know how this works. That wouldn't be me however.

FFT gain wouldn't apply to defined frequencies like harmonics, but it does for a wideband noise floor.

So do you have anything useful to add or just trying to see how far you can get with muddying the waters?
 

finneybear

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Well this might impress those who don't know how this works. That wouldn't be me however.

FFT gain wouldn't apply to defined frequencies like harmonics, but it does for a wideband noise floor.

So do you have anything useful to add or just trying to see how far you can get with muddying the waters?

So what's your definition of harmonics? Any band pass process to let certain frequency windows to pass? LOL

We were doing tests to see the real performance, not for showing off purpose. We did not want any FFT gain.
Some processing tricks here and there. Again, it's beyond the scope of discussion here.

We did the tests and we knew what we were doing yet you are here to claim to know what we were doing?
I am impressed with your self-confidence yet I am afraid that confidence is placed at the wrong place.
 

finneybear

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Well this might impress those who don't know how this works. That wouldn't be me however.

FFT gain wouldn't apply to defined frequencies like harmonics, but it does for a wideband noise floor.

So do you have anything useful to add or just trying to see how far you can get with muddying the waters?

Oh, BTW, FFT gain actually does not work by passing predefined frequencies. It works in a different way.

This just shows how much you know about FFT gain. LOL
 

Blumlein 88

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Oh, BTW, FFT gain actually does not work by passing predefined frequencies. It works in a different way.

This just shows how much you know about FFT gain. LOL
Then could you enlighten us or this just part of the magical mystery tour? Magical funnybear.
 

Blumlein 88

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So what's your definition of harmonics? Any band pass process to let certain frequency windows to pass? LOL

We were doing tests to see the real performance, not for showing off purpose. We did not want any FFT gain.
Some processing tricks here and there. Again, it's beyond the scope of discussion here.

We did the tests and we knew what we were doing yet you are here to claim to know what we were doing?
I am impressed with your self-confidence yet I am afraid that confidence is placed at the wrong place.
So again, do you have a point to make? Implying you know plenty more, but refusing to say what it is doesn't really do much does it. Its some bait switch type of bs. Oh well the audio world is full of bs. It apparently makes the world go round.
 

finneybear

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Then could you enlighten us or this just part of the magical mystery tour? Magical funnybear.

Enjoy your humor. Unfortunately it does not help any discussion here. Next time, maybe. LOL

Lets get back to this DAC instead. Still waiting for the designer to come back.
 

vitalii427

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Even more, this thing has discrete IV, discrete LPF, and discrete buffer. No OPs!!! No negative feedback!!
Yes, you can still get very good measurement numbers with discrete IV!
Those harmonics can be reduced a lot by adding negative feedbacks, BTW.
So could you explain what is downside of OPs and negative feedback pls?
 

finneybear

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So could you explain what is downside of OPs and negative feedback pls?

I will not associate them with terms as *downside*. Negative feedback is one crucial design technique and in most situations it is a must have.
OP as a standardized part, is a super useful component which is used everywhere and it gives you effective and consistent result.

As you can see from the FFT chart I showed above, with no negative feedback, the distortions, the harmonics would jump high.
The key is human ears are not measurement instruments, some ears may actually love those harmonics. The music just sound more alive.
Another argument is negative feedback may generate phase shift which human ears do not like. So people start to design those high speed amps to reduce the phase shift. In general, NFB or not, is up the designers to choose, as far as the machines are stable and can sell, they can do whatever they want to.

OP works by high open loop gain and feedback loop. You can get very good performance out of it. And companies keep bringing out higher performance parts every year. Some claim they can identify OP sound yet personally I feel it is a mix of everything. Nothing conclusive.

My take is a DAC should at least have a set of decent performance numbers. After that, it's up to the consumer to decide. There are way too many marketing games in this business.
 

Veri

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Yes, level matching is one major trick HiFi shops used to confuse people. Even accurate level matching is not really fair. There are other factors involved.

Here is the Khadas chart:

View attachment 21149

It has an impressive performance for its price, and more than good enough for most people.
Still, I can see problem in this chart and I will not call it transparent. Some people may still not like it.

What problem?
 

finneybear

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What problem?

Originally I was confused with your asking. Now I am see what you are asking.

Take a look at the bump around 10KHz. Nothing major as they are all very low.
However, when you have multiple tones, things will add up.
For most people, you dont have to worry about it.
 

maty

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The key is human ears are not measurement instruments, some ears may actually love those harmonics. The music just sound more alive.
Another argument is negative feedback may generate phase shift which human ears do not like. So people start to design those high speed amps to reduce the phase shift. In general, NFB or not, is up the designers to choose, as far as the machines are stable and can sell, they can do whatever they want to.

Class A and class AB amps have little phase shift. About 6 degrees at 20 kHz or less. It is not a problem, hence very few specify it!

In diyaudio.com, some designers defens NFB < 30 dB if you want sound more realistic and 3-D. If you add SET topology (H2 predominance) then you can have a tube sound without the great distortions. H2 level? designer choice. Of course, with H3 10 dB lower than H2. Better without other harmonics < 90 dB.

Amp bandwith better < 350 kHz to avoid RF/EMI interferences.

With greater NFB the numbers are better but the sound is more sterile, they say.
 
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