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Denafrips DACs might not actually be NOS?


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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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Hi @The Computer Audiophile, it's just you've always seemed reasonable on the forum and I had seemed to wind you up - like I say, I had no idea at the time you had reviewed it. You're absolutely right not to revise your opinion on how this pairing sounds, 

You're absolutely right to try and avoid "gotcha" moments to embarass manufacturers, but there certainly is something that isn't quite as described here. The thing I'm finding interesting is that people are so set against a certain design - so e.g. R2R NOS people who hate D/S, but then use a PC to increase sample rate and reduce word depth to improve linearity... which is exactly what most D/S designs do...

I've been very careful to try and talk in general terms, rather than specific products, so I'm hoping to be a positive rather than a negative

 

your friendly neighbourhood idiot

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@The Computer AudiophileSorry but you keep repeating as if this could be some NOS/OS grey area. It is clearly OS, as confirmed by others based on all the evidence presented. 

If you think it isn't or have doubts, feel free to explain. 

 

A NOS DAC always plays exactly what you feed it without digital processing, be that hi res, red book or OS data at any sample rate, this is how every early Multibit dac chip operated and is where the definition came from.

 A grey area would be others forms of DSP like equalisation,

OS, that is a process that increases the sample rate of the input and adds new samples, is obviously not one.

 

 

 

 

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@semente - to clarify, it was asked if this product was a NOS or not. This had led us to two entirely separate users of NOS:

Type A: This user wants to leverage the processing of a PC to do filtering and noise shaping to present very high rate processed data to the DAC, with as little DSP inside the DAC as possible to interfere with the PC processing ( so. e.g. The Computer Audiophile )

Type B: This user wants the original samples from the source presented directly to a simple DAC at the original sample rate, usually because the claim is this is "purer" or they just prefer the sound ( e.g. etane )

 

Both want a "NOS" DAC, but for entirely different reasons. The denafrips DACs *appear* to be doing a linear interpolate ( or average ) for sample rates below it's internal processing.

 

This is probably ideologically incompatible with Type B, and the frequency response is (measurably) poorer than an already droopy NOS ( so exactly twice as droopy for point of reference - a "real" NOS is about 3dB down at 20kHz, a linear interpolate about 6 for red book )

For Type A users, however, they are probably feeding it at it's native sample rate, or at a rate where the linear interpolate is effectively not worth worrying about, so is completely OK.

 

It's entirely possible that this linear interpolate thing could be corrected by a firmware update in the future, I have no idea if these units can be updated in the field, however as it stands it's a peculiarity that is definitely there, and we have had no response from the manufacturer.

 

Does this make sense?

 

your friendly neighbourhood idiot

 

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3 hours ago, semente said:

Are there different kinds of NoOverSampling?

 

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.

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12 minutes ago, idiot_savant said:

Type A: This user wants to leverage the processing of a PC to do filtering and noise shaping to present very high rate processed data to the DAC, with as little DSP inside the DAC as possible to interfere with the PC processing

 

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.

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2 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.

To make things clearer what we are all  discussing here is upsampling incorrectly named oversampling or OS , would that be right? Oversampling wouldn't be something you see ever in PCM dacs?

 

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2 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.

Agreed, this is simply not NOS. no such thing as 'little bit NOS'

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Oversampling is exactly the same as upsampling. It means that by some algoritme the sample rate is increased. Often in combination with an low pass filter like Sinc, FIR of even IIR. Oversampling by linear interpolation is a very crude way oversampling and should be avoided for hifi.

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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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HQPlayer Desktop / Mac mini → Intona 7054 → RME ADI-2 DAC FS (DSD256)

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1 minute ago, numlog said:

Oversampling wouldn't be something you see ever in PCM dacs?

 

This is something I am not good at, but I would say that this can exist, BUT then it is not a NOS DAC. Thus, PCM is not equal to NOS.

The other day I mentioned the PCM1792 ad a hybrid D/A chip. IIRC it can upsample (???) and use its filters from there, or it may not upsample, but still the filter behind it can't be shut off. It would be a PCM DAC, that upsamples.

I hope someone corrects me here.

 

Possibly all DACs using PCMxxxxx chips should be called PCM DAC's. But this is then only because it is not an SDM based DAC.

I should be looking in the datasheet for this ...

The difference would be "no modulator" involved with the PCM based DAC.

 

There is (was) only one chip which was able to "be" NOS at 24 bits, and this is the PCM1704. Officially that one was to be used with the filter chip behind it (DF1704 or something like that). Here the "trick" was that the PCM1704 was UPsampled towards that filtering chip, BUT that we could leave out that filtering chip and apply the upsampling IN ADVANCE. This is how the NOS1 emerged and how it can do 24/768. And the by now known specialty, do the upsampling/filtering in-PC.

 

To be not too much confusing, I should emphasize that both Miska and me were working on the very same principle, say from of 15 years ago : overrule what the DAC does with PC software. And the nice division: I do it with PCM and he does it with DSD (or makes it that). This makes the target DACs inherently different (PCM vs SDM based, respectively).

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43 minutes ago, idiot_savant said:

The thing I'm finding interesting is that people are so set against a certain design - so e.g. R2R NOS people who hate D/S, but then use a PC to increase sample rate and reduce word depth to improve linearity... which is exactly what most D/S designs do...


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. 

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37 minutes ago, numlog said:

@The Computer AudiophileSorry but you keep repeating as if this could be some NOS/OS grey area. It is clearly OS, as confirmed by others based on all the evidence presented. 

If you think it isn't or have doubts, feel free to explain. 

 

A NOS DAC always plays exactly what you feed it without digital processing, be that hi res, red book or OS data at any sample rate, this is how every early Multibit dac chip operated and is where the definition came from.

 A grey area would be others forms of DSP like equalisation,

OS, that is a process that increases the sample rate of the input and adds new samples, is obviously not one.

 

 

 

 

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?

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6 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?

No, that is only speculation. We have no idea if it overrides internal OS at 1.5Mhz, and if it does then it would also do so in OS mode.

Perhaps they should they rename the OS mode to 'NOS mode 2',

or more accurately rename NOS mode to 'OS mode 2'

 

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You can dive endlessly in the specs of this chip and still end up with not what you want:

 

image.png.bd8977203b5f94ed0b4ac0af968b03f0.png

 

 

But look at the 8x oversampling digital filter.

Nobody (datasheets) calls that upsampling.

 

Now look at my or anyone's playback software. Nobody calls that oversampling.

 

The PCM1792 is natively 768 (see above last line). The 8x oversampling exists outside of that. Does this make the 1792 a 6144K sampling chip ? no. Instead the 768 is "re-sampled" (hey !) and the result is for the filter (or it *is* that right away).

 

Often the oversampling is related to the native sampling rate of the chip. For example, it can take 768, and o.s. 8x but if it is fed with 384 it may o.s. 16x.

 

PS: While this is from 2006 edit 2003, the 1704 is from 1996 or whatever exactly. Still this 1792 is worthless for NOS. It is good for DSD, however (no 1704 can do that).

 

Blurp.

 

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3 minutes ago, PeterSt said:

The PCM1792 is natively 768 (see above last line).

 

This is probably not correct and officially it is 192. Apologies.

Similar (but other way around) with the 1704. This is officially 96 but can do 768.

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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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39 minutes ago, PeterSt said:

 

I understand. If I would have one other example, I would have used that definitely. But I know of no other example. I will also 100% definitely know about my own product.

 

I'll be extra careful. Thank you for the warning.

 

Thank you for that. I appreciate manufacturers, like you, who do try to play fair.

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Quoting from a very good post:

 

11 minutes ago, idiot_savant said:

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.

 

I wonder whether you/someone noticed this from the  Stereophile measurements:

 

image.png.ce5964dd6279a06aea44d7f8dbfa023d.png

The early roll of (L/R) is from the 192KHz sampling rate. The later (but still strangely early) roll of is from 96KHz.

So again I just see a bug in the (FPGA) software somewhere.

 

But otherwise, I.S., maybe this gives you a clue somewhere ?

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