Denafrips DACs might not actually be NOS?

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On 5/14/2021 at 2:45 PM, idiot_savant said:

Your friendly neighbourhood idiot

Haven’t been around that frequently, didn’t realise that you were back.

Good news.

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24 minutes ago, davide256 said:

Seems to me that would be a discussion between tester (Stereophile) and Denafrips.

 

I thought that the tester was the OP @GoldenOne. From my understanding JA only chimed in later, although he was also a tester.

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15 minutes ago, davide256 said:

The OP is a Youtube audio reviewer with 12K subscribers... they have a venue thats more suited to attract a manufacturers attention. There is also a review of the Pontus on this site... comments there are more likely to get a response as prospective purchasers will be affected. A random forum discussion... not  likely to get a response

 

The post that you quoted does not appear to be engaging Denafrips in the discussion.

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16 minutes ago, The Computer Audiophile said:

I think the issue is that we are missing a bunch of information and people are just speculating. That’s only slightly interesting to most people. 

 

And it upsets fanboys...

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VW brought us the emissions-gate. And now we have the NOS-gate.

 

What a strange world.

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2 minutes ago, idiot_savant said:

@GoldenOne you are, of course correct, in that filters should have less effect the higher in sample rate you go, so that brings us back to what is the point of a NOS mode at lower sample rates?

do you happen to know anything about the Holo analogue reconstruction filter? I can’t see it doing much good unless matched with an OS filter?

 

your friendly neighbourhood idiot 

 

It doesn't seem to be doing much:

 

HoloAudio May, NOS mode, wideband spectrum of white noise at –4dBFS (left channel red, right magenta) and 19.1kHz tone at 0dBFS (left blue, right cyan) into 100k ohms with data sampled at 44.1kHz (20dB/vertical div.).

https://www.stereophile.com/content/holoaudio-may-level-3-da-processor-measurements

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7 hours ago, The Computer Audiophile said:

But using HQP you can take this DAC way farther than any internal filtering and over sampling could do. The horsepower in any DAC is just too weak to do what HQP does. That’s why people like NOS type DACs. 

 

Some people like NOS DACs with Redbook too, often driven by CD transports. It's easy to forget that files are not the only format, perhaps not even the most common.

Several NOS DACs are limited to 16-bit and 44.1/48kHz. Philips' entry-level TDA1543 D/A chip is a favourite for its low price and if I'm not mistaken ease of implementation.

I tried NOS with CD for a while back in the day, with a Shigaraki transport+DAC combo.

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7 hours ago, botrytis said:

 

Mercedes, Audi, BMW, GM, and Ford were all caught in the emissions-gate also - VW was the the tip......

 

I know that.

It was supposed to be a joke, but if you and @The Computer Audiophile didn't get it then maybe I should have added a cheeky smiley face.

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3 hours ago, idiot_savant said:

Is an R2R NOS DAC still "pure" if you have a PC doing OS & noise shaping to help linearise it?

 

If you are performing OS & noise shaping using software and a computer then ideally your DAC should be just a D/AC (no internal SRC, no filtering).

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23 minutes ago, idiot_savant said:

I mean if the concepts aren't defined properly then implementations are irrelevant? I'm talking about thought experiments. If you posit that by using more horsepower for a task in a PC you can get a measurable parameter that is better than doing it internally, that must be quantifiable?

 

This post could help (compares NOS, internal SRC and filtering, external SRC and filtering) but the formating has gone bad (maybe @The Computer Audiophile can sort it?):

 

Also this topic: https://tinyurl.com/n8epw24r

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Just now, idiot_savant said:

 

But using HQP you can take this DAC way farther than any internal filtering and over sampling could do. The horsepower in any DAC is just too weak to do what HQP does. That’s why people like NOS type DACs. 

 

Yes, some people like NOS DACs (a list here) so that they can feed them previously upsampled and filtered and noise-shaped Redbook.

 

But other people like NOS DACs with Redbook. People using Audio Note, Lampizator, Border Patrol, AMR, 47Labs, Zanden, etc. DACs.

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35 minutes ago, PeterSt said:

I would say that there's not a single soul any more who uses a DAC without the filtering in advance of it. Thus, everybody uses some kind of in-PC filtering.

 

Peter, how long have you been in self isolation for? I am a member of other forums and most people there do not use a computer, nor a streamer.

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I wonder if this can shed some light:

 

PHILIPS OVERSAMPLING SYSTEM FOR COMPACT DISC DECODING

April 1984 
The sampling process which converts a digital audio signal from binary numbers back to its original analog form generates spurious frequencies, which must be filtered out of the final wave form. Most brands of Compact Disc players use analog filters for this, usually in a system consisting of a 16 -bit D/A converter, a sample -and -hold circuit, and an analog low-pass filter (Fig. 1).

 

 

This, however, can be difficult to do accurately. First, the D/A converter must be linear to within one-half the value of the least significant bit (LSB). However, '/2-LSB accuracy of the dividing steps becomes more and more difficult to achieve as the number of such steps, or bits, increases. For 16 -bit D/A converters, low yield and high cost can easily be obstacles to practical manufacture.

 

"By oversampling at fourtimes the original sampling frequency, the original noise energy is now spread over a band four times as wide."

 

A second problem is caused by analog filtering. A filter steep enough to adequately remove residual components above the audio band must inevitably be a complex one, degrading the signal accuracy and introducing phase distortion. Even an active lowpass filter has a large amount of phases shift near its cut off frequency. Such a filter also generates noise and requires high-speed operational amplifiers, which have high power dissipation and require tight component tolerances to maintain low ripple in their pass -band. Temperature changes and component aging of such filters also affect performance adversely.

 

Philips engineers have found a way to carry out most of the essential filtering process digitally. This approach is used in the players sold by Philips under its own name and under its U.S. brand names of Magnavox and Sylvania. It has also been adopted, in whole or in part, by some other manufacturers.

 

continues here -> https://www.dutchaudioclassics.nl/Philips-oversampling-system-for-compact-disc-decoding/

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4 minutes ago, etane said:

I can't directly answer your question as I am not technically inclined.  I drank 47lab's koolaid and understood the reason why NOS dacs are the only digital source I could effortless listen to is because it lacks brick filter, O/S, PLL and such.  Whether the source hardware is PC or software is not redbook, I don't think it matters.  I think it does matter that additional processing is added to the DAC chip.  To some, it's like adding ketchup to sushi.

 

 

 

You need to cut down on the koolaid, the additional processing results in a more accurate reproduction of the signal.

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36 minutes ago, manueljenkin said:

The last sentence is just your assumption.

 

Is a wrong assumption?

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12 minutes ago, numlog said:

 

On paper, same as how on paper most Delta Sigma dac is unquestionably superior to most Multibit dac when in the real world many would not agree. Or how, on paper, any effect of a computer on DAC output must be imaginary since bits are bits. The list goes on and on.

 

In my view more accurate reproduction is not a matter of opinion or of taste.

People like what they like, that is preference.

Accuracy is measurable performance.

I can't say if it is possible measure everything that we can hear but to my knowledge OS measures better in most parameters.

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42 minutes ago, etane said:

You sound like you're from ASR.  But, yes there's more than one way to skin a cat.  But, what I was driving at is how NOS is defined and that's as much as I could do with a technical definition.

 

There are many ways to skin a file (let's leave the cat out of this), but some produce more a accurate reconstruction of the original signal than others.

Which "sounds better" depends on personal preference, on taste, on who you ask.

It sometimes happens that accurate "sounds better", other times it does not.

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15 minutes ago, numlog said:

Nor mine, if only all aspects of accurate reproduction were understood and measured.

The problem with OS and NOS debate in my opinion is the disconnect between the digital realm and analog realm, digital realm is represented by electrical signals in analog realm, digital is purely mathematical and 'perfect' but we listen in the analog realm, where these 'perfect' rules dont apply and evidently there are some very complex and poorly understood interactions taking place.

 

I am conscious of my limited understanding.

I am also conscious that "sound quality" is a matter of preference. If that were not the case there wouldn't be any of the valves vs. transistors, vinyl vs. digital, omni vs. monopole vs. dipole, NOS vs. OS, DSD vs. PCM debates.

 

The problem with these debates in my opinion is the disconnect between "sound quality" and accuracy or measured performance. How can accuracy be better if it doesn't "sound better"? Except that it does, to some people. And there we go, round and round.

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1 hour ago, idiot_savant said:

@jventer - hi, it’s gotten a bit off topic, but at standard sample rates at least ( so we have measurements at 44, 96 & 192 ) the denafrips DACs are not NOS, but this *may* not matter depending on what kind of NOS you want

 

@sdolezalek - actually, this isn’t really a subjectivist vs objectivist test - we don’t know how the combination ( HQPlayer and denafrips ) measures, and ( just now ) reading the review we don’t know how the denafrips sounds on its own

 

@The Computer Audiophile - I didn’t actually realise you had reviewed this pair, and perhaps were taking my comments as a negative against you, which I really wasn’t - I’ve never said anything about how I thought the pair would sound, and have been trying to distance the discussion from particular implementations. In this case, I’m willing to bet that HQPlayer is turning off a number of LSBs and using this to noise shape the MSBs. Probably worth pointing out that noise shaping is tricky in terms of maths but easy peasy in terms of resource - I’ve seen 30 year old ADCs that can do this, at lower rates admittedly

It just ( again ) brings into focus the obsession with architectures - what do you call a D/S OS ( R2R NOS )  thing?

 

your friendly neighbourhood idiot

 

Are there different kinds of NoOverSampling?

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1 hour ago, idiot_savant said:

Well, if you’re feeding it 1.5MHz it probably is NOS. 

If you’re a red book NOS user it isn’t really

 

your friendly neighbourhood idiot 

 

Sorry, you've lost me there. Are you referring to the Denafrips or to NOS in general which was what I was asking about?

 

I had a 47Labs DAC once. I used the TDA1543 and it only allowed Redbook input over coaxial, it didn't oversample and it didn't filter (no digital filter), not sure if it had an analogue low-pass.

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9 minutes ago, PeterSt said:

 

With discrete ladder DACs, I am afraid the answer can be Yes, although this will probably not be what you mean (to ask).

 

... I am pretty sure that this boils down to what Oversampling actually is, and this is not the same as Upsampling. Examples:

 

Suppose I have that discrete DAC and it is 17 bits at least, then I would be able to UPsample the data in advance of the D/A, so 16/44.1 would become 17/88.2. The DAC would be NOS because, well, it is not OVERsampling.

Technically there would be no difference with the in-DAC solution vs the outboard (PC playback software) solution, and the sound will depend of the kind of filtering used. Also notice that leaving out reconstruction filtering will make no sense.

 

When I have an SDM (chip) based DAC and I feed that 16/44.1, it may OVERsample to whatever idiot rate, so the modulator works with decent feedback. The number of bits is not importance any more because that is how the modulator works (with 1 bit, or a few bits, whatever, but not 16 or 17 or 24 or 32). Although it may be hard to find proper definitions, I myself regard oversampling as a kind of sampling the samples (again). This should be done at a (way) higher rate than the original is.

Also, from an SDM based DAC it will generally not be known what its sampling rate is, because it is unimportant.

Notice that this is different from the INPUT rate of a DSD DAC. And as far as I can tell, that too can still oversample.

 

Do I make sense ?

Completely incorrect ?

 

PCM-me.

 

I get the distinction that you are trying to make in regard to PCM -> R2R vs. PCM -> SDM.

 

But why is one called UP and the other OVER?

 

I can upconvert Redbook to PCM705.6 and the result can be fed to either a R2R D/A or an SDM D/A. The difference is that the latter will run the signal through the modulator.

Is this process why you call feeding an RME PCM705.6 Oversampling and feeding a Holo PCM705.6 Upsampling?

 

Also many SDM DACs will as far as I know Upsample PCM to the maximum admissible rate and then feed the modulator. Should I have written Oversample?

 

And what the modulator does, is it Up-sampling, Over-sampling, of Modulating?

 

Yes, I'm confused Peter... 🤔

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13 minutes ago, PeterSt said:

 

I am sorry, but it this is the way NOS is explained, than about everything is OS, if only "as little as possible DSP" is performed.

So No, no DSP at all.

 

One thing could be excluded, and this is volume control. That is, if we regard that DSP too. But on top of it all, the volume control, thus proposed as digital, should be lossless.

 

I myself would not even incorporate dither.

 

In other words NOS is pass-through from input to D/A chip?

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34 minutes ago, The Computer Audiophile said:

This hobby, like most, is full of people along a continuum. If you look hard enough you’ll find people doing just about everything, even when it seems quite nonsensical. 
 

I don’t think it makes much sense to be against a design in general. It’s all about implementation and the end result. That’s just me though. 

 

29 minutes ago, The Computer Audiophile said:

No. 
 

its NOS at 1536 kHz, which is how I use it. 
 

The world is full of gray areas. As much as you try to put everything in a black or white box, this doesn’t make it so. 
 

I don’t understand your push to be so rigid. We don’t have a category for this DAC. Can you be OK that, or must you call it OS which it clearly isn’t?

 

I think that for the die-hard "bit-perfect" NOS fan wishing to playback his CDs or Redbook files the Denafrips should not be advertised as a NOS DAC if it is indeed doing interpolation or sample-hold or whatever.

 

For someone like myself who uses HQP into a NOS DAC at its highest admissible rate Denafrips' DACs were strong candidates on my shopping list.

So I would like to know if Denafrips' NOS mode is really NOS as in no processing is being done.

 

From that perspective, which I am sure many will share, it doesn't matter whether or not the DAC sounds good, be that to you, me or anyone else.

 

In other words, does it do what it says in the tin?

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11 minutes ago, idiot_savant said:

Hi,

 

linear interpolation doesn’t add *any* delay - in the Chord, it will be the FIR filtering adding the delay. In a NOS DAC, what processing is going on?

 

It *looks* like a FIFO, which is why we’re trying to look at what’s going on. A FIFO is generally a good thing, but adds delay, so the question is why so much delay, and so variable?

 

 

your friendly neighbourhood idiot 

Is theFIFO used as buffer before reclocking?

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On 7/21/2021 at 4:28 PM, Blake said:

Anecdotally, it seems that in some instances better measurements don't necessarily correlate to subjective listener perceptions of a better sounding product.

The problem is that it depends on the listener, it's a matter of personal preference.

In other words, not everyone likes the same "presentation".

 

Ultimately each individual will have to go the extra mile and learn how to correlate his preferences with measurements. Easier said than done, particularly with electronics.