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Denafrips DACs might not actually be NOS?


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26 minutes ago, idiot_savant said:

Now I'm guessing that it *is* genuinely NOS at 1.5MHz.

 

Its possible, but also possible the internal rate exceeds 1.5Mhz.

On the Soekris R2R dacs the final upsampling rate is 2.8Mhz, exceeding max possible input rate and making ''NOS'' impossible.

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Excellent! I'm assuming you can do FFTs and generate test tones?

Lets do an experiment:

Let us generate a 44.1kHz 24 bit -60dBFS 1kHz sine wave

 

In all cases, NOS mode on the DAC.

 

1)play that using HQPlayer no oversampling, grab FFT @ 768kHz

2)play that using HQPlayer, 1.411MHz, grab FFT @ 768kHz

3)play that using HQPlayer, 1.411MHz, noise shaped ( I don't know the options - 5th order? ) to 16 bits, grab FFT @ 768kHz

4)play that using HQPlayer, 705.6kHz, noise shaped to 16 bits ( same settings ), grab FFT @ 768kHz

 

I'm honestly guessing at the 16 bit number here, it would be helpful if @The Computer Audiophile shared his settings?

 

If you could, that would be most excellent,

 

your friendly neighbourhood idiot

 

 

 

 

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3 minutes ago, idiot_savant said:

Excellent! I'm assuming you can do FFTs and generate test tones?

Lets do an experiment:

Let us generate a 44.1kHz 24 bit -60dBFS 1kHz sine wave

 

In all cases, NOS mode on the DAC.

 

1)play that using HQPlayer no oversampling, grab FFT @ 768kHz

2)play that using HQPlayer, 1.411MHz, grab FFT @ 768kHz

3)play that using HQPlayer, 1.411MHz, noise shaped ( I don't know the options - 5th order? ) to 16 bits, grab FFT @ 768kHz

4)play that using HQPlayer, 705.6kHz, noise shaped to 16 bits ( same settings ), grab FFT @ 768kHz

 

I'm honestly guessing at the 16 bit number here, it would be helpful if @The Computer Audiophile shared his settings?

 

If you could, that would be most excellent,

 

your friendly neighbourhood idiot

 

 

 

 

I'll do this shortly. Though keep in mind my ADC only goes up to 768khz so when running at 1.536mhz on the DAC I may not actually be able to detect all that much, but will see!
This is the kind of area where an analyzer would come in very handy. I'm working towards getting an APx555 at the moment, all patreon income is going towards that. That's got a 1Mhz bandwidth so would be great here

Additionally though, I'd say that when feeding a DAC 1.536mhz it almost doesn't matter what filter it's running as the information is so high bandwidth anyway. The discussion/OP was about what happens to 44.1khz content. HQP brings a benefit to D/S dacs with oversampling so I'm sure the same would happen here.

https://youtube.com/goldensound

Roon -> HQPlayer -> SMS200 Ultra/SPS500 -> Holo Audio May (Wildism Edition) -> Holo Audio Serene (Wildism Edition) -> Benchmark AHB2 -> Hifiman Susvara

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APx555 is pretty cool, and would make everything much easier

 

What I think might happen is

(1) will be classic NOS ( so images everywhere )

(2) will be nicer ( so no images ), but probably a few tones from R2R

(3) will be nicer still ( no images, possibly fewer tones, possibly lower noise )

(4) much like (2), maybe a bit noisier

 

All of which should be visible @ 768k rates.

 

your friendly neighbourhood idiot

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1 hour ago, idiot_savant said:

Erm, I've had a bit of a ponder about this, and I think there genuinely could be a problem here, but it's quite complicated so bear with me...

So the big problem with R2R DACs is matching the ladder, because the tolerances required are mind-bogglingly tight ( so the MSB has to be exactly 8 million or so times bigger than the LSB ). So the HQPlayer approach suggested by Miska, which is to effectively trade bit depth for sample rate ( much like D/S do ) relies on effectively turning off the bottom bits, and using this noise in a noise shaper - this means that the noise floor changes, so it's actually as good as it was ( potentially better ) in the audio band, but higher in the inaudible region, and the LSBs that effectively only contribute noise and disortion products are removed from the equation. Clever, eh?

Now the problems come if the DAC does any further processing, as *if* it does, *any* kind of processing will turn on those pesky bottom bits again - think digital volume control, linear interpolators...

 

Now I'm guessing that it *is* genuinely NOS at 1.5MHz, but we *know* it isn't at say 192k, so when the linear interpolate is active the PC provided noise shaping is effectively ruined. If someone has one with test equipment and HQPlayer, we could do some measurements which would be fun. 

 

To be fair, PeterSt saying he didn't think volume control was proper DSP kind of triggered this...

 

As I keep repeating, this *should* be fixable in firmware, and is not particularly obvious... and if anyone from denafrips would like to buy me a drink, that'd be grand.

 

your friendly neighbourhood idiot.

 

Without identifying an issue, you suggest that something is fixable and give yourself credit. I don't follow. 

 

 

 

 

 

 

 

49 minutes ago, idiot_savant said:

Excellent! I'm assuming you can do FFTs and generate test tones?

Lets do an experiment:

Let us generate a 44.1kHz 24 bit -60dBFS 1kHz sine wave

 

In all cases, NOS mode on the DAC.

 

1)play that using HQPlayer no oversampling, grab FFT @ 768kHz

2)play that using HQPlayer, 1.411MHz, grab FFT @ 768kHz

3)play that using HQPlayer, 1.411MHz, noise shaped ( I don't know the options - 5th order? ) to 16 bits, grab FFT @ 768kHz

4)play that using HQPlayer, 705.6kHz, noise shaped to 16 bits ( same settings ), grab FFT @ 768kHz

 

I'm honestly guessing at the 16 bit number here, it would be helpful if @The Computer Audiophile shared his settings?

 

If you could, that would be most excellent,

 

your friendly neighbourhood idiot

 

 

 

 

 

 

Excellent. I'll post the settings I use in HQP.

 

 

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16 minutes ago, The Computer Audiophile said:

Here are the settings I use in HQP with the Terminator.

 

Chris, DAC Bits 20 would be insufficient for upsampling 32x.

Possibly I misinterpret things (I don't know HQP well).

32x in my own book requires 21 bits at least.

Lush^3-e      Lush^2      Blaxius^2.5      Ethernet^3     HDMI^2     XLR^2

XXHighEnd (developer)

Phasure NOS1 24/768 Async USB DAC (manufacturer)

Phasure Mach III Audio PC with Linear PSU (manufacturer)

Orelino & Orelo MKII Speakers (designer/supplier)

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7 minutes ago, idiot_savant said:

@The Computer Audiophile - thanks for this, denafrips should be thanking us for debugging their product?

@GoldenOne Actually, can you make the tone -6dBFS rather than -60?

 

your friendly neighbourhood idiot


I’d hold off on claiming you’re debugging anything. If it’s working as designed, you’re doing exactly what I feared and wrote about earlier. 

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9 minutes ago, PeterSt said:

 

Chris, DAC Bits 20 would be insufficient for upsampling 32x.

Possibly I misinterpret things (I don't know HQP well).

32x in my own book requires 21 bits at least.

I wouldn’t make bold claims without understanding how something works. Questions are always good, but you know people will grab your first statement and run with it, without all the facts. 

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2 minutes ago, idiot_savant said:

@The Computer Audiophile if 1,2 and 3 perform as expected, this is great for denafrips and HQPlayer?

 

if 4 responds as I expect this is a minor bug that can be fixed, and if it doesn’t I’m an idiot?

 

@PeterSt - noise shaper…

 

your friendly neighbourhood idiot 

 

I'm not claiming it's great for anyone or you're an idiot. Stop with the nonsense. 

 

All I'm saying is that you are edging closer and closer to the camp of folks I mentioned above. 

 

You can't conclude much without actually talking to Denafrips. You can't call something a bug, if it's designed to work that way. Perhaps there's a tradeoff involved. The thing is, we don't know until someone talks to Denafrips. The last I heard is that the company didn't want to talk because it didn't want to let others know what it was doing and why. 

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(BTW, I am not suggesting that the OP or idiot_savant is trying to take down Denafrips. I too, find this topic interesting in the positive sense of the word.)

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