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Is DoP such a bad thing?


Jabs1542

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I see that we tend to want direct DSD rather than the DoP implementation of DSD. I can listen to DSD64 and DSD128 in either mode (JRMC for DoP and HQP for direct - note, no up sampling involved). When comparing the SQ of these modes nothing is really jumping out at me. Investigation exactly what DoP is I came up with this as a good summary explanation:

 

DoP open Standard | DSD-Guide.com

 

So I ask, what is so heinous about DoP?

Analog: Koetsu Rosewood > VPI Aries 3 w/SDS > EAR 834P > EAR 834L: Audiodesk cleaner

Digital Fun: DAS > CAPS v3 w/LPS (JRMC) SOtM USB > Lynx Hilo > EAR 834L

Digital Serious: DAS > CAPS v3 w/LPS (HQPlayer) Ethernet > SMS-100 NAA > Lampi DSD L4 G5 > EAR 834L

Digital Disc: Oppo BDP 95 > EAR 834L

Output: EAR 834L > Xilica XP4080 DSP > Odessey Stratos Mono Extreme > Legacy Aeris

Phones: EAR 834L > Little Dot Mk ii > Senheiser HD 800

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Who said it was heinous? ... Someone who doesn't understand what it is.

 

DoP is DSD - the DSD isn't altered. It is just disguised in a 24/176 frame so it can be sent over USB to DSD DACs whose drivers only work with PCM. The actual playback by the DAC is the same as a non DoP DSD file.

 

It's not DSD converted to PCM.

 

An extremist/purist position would say that DoP playback entails a tiny amount of extra processing, ergo it is "bad". Can you (or anyone else) hear a difference? I doubt many/any can.

 

I see that we tend to want direct DSD rather than the DoP implementation of DSD. I can listen to DSD64 and DSD128 in either mode (JRMC for DoP and HQP for direct - note, no up sampling involved). When comparing the SQ of these modes nothing is really jumping out at me. Investigation exactly what DoP is I came up with this as a good summary explanation:

 

DoP open Standard | DSD-Guide.com

 

So I ask, what is so heinous about DoP?

Main listening (small home office):

Main setup: Surge protector +_iFi  AC iPurifiers >Isol-8 Mini sub Axis Power Conditioning+Isolation>QuietPC Low Noise Server>Roon (Audiolense DRC)>Stack Audio Link II>Kii Control>Kii Three >GIK Room Treatments.

Secondary Listening: Server with Audiolense RC>RPi4 or analog>Matrix Element i Streamer/DAC (XLR)+Schiit Freya>Kii Three .

Bedroom: SBTouch to Cambridge Soundworks Desktop Setup.
Living Room/Kitchen: Ropieee (RPi3b+ with touchscreen) + Schiit Modi3E to a pair of Morel Hogtalare. 

All absolute statements about audio are false :)

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Thank you, it seems to me like it should be pretty harmless - just wanted to check.

 

I see people stating that DoP is a deal breaker them, this is in the DAC forum and the Software forum.

Analog: Koetsu Rosewood > VPI Aries 3 w/SDS > EAR 834P > EAR 834L: Audiodesk cleaner

Digital Fun: DAS > CAPS v3 w/LPS (JRMC) SOtM USB > Lynx Hilo > EAR 834L

Digital Serious: DAS > CAPS v3 w/LPS (HQPlayer) Ethernet > SMS-100 NAA > Lampi DSD L4 G5 > EAR 834L

Digital Disc: Oppo BDP 95 > EAR 834L

Output: EAR 834L > Xilica XP4080 DSP > Odessey Stratos Mono Extreme > Legacy Aeris

Phones: EAR 834L > Little Dot Mk ii > Senheiser HD 800

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Anyone that says DoP is inferior to Native DSD does not understand how DoP works, and is getting scared by the "DSD over PCM" part.

It's exactly the same data, just packaged differently.

 

If anything, I would think that transmitting a 176kHz signal would be more reliable than 2.8MHz.

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A lot of DACs had/have trouble switching between DSD over DoP and other formats/resolutions without nasty artifacts like pops and clicks. Enough bad experiences with this that DoP is a dealbreaker for me.
Isn't that due to DSD's sensitivity to DC offset or bad rips rather than anything specific to DoP?
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A lot of DACs had/have trouble switching between DSD over DoP and other formats/resolutions without nasty artifacts like pops and clicks. Enough bad experiences with this that DoP is a dealbreaker for me.

 

Huh? Are you saying that those same DACs do just fine switching between ASIO DSD and PCM? I don't think DoP is the culprit, but instead the switching of formats and the dc offset issues, etc (as Skeptic has pointed out as well).

 

BTW, Stereolab, this next comment is not pointed at you: but I continue to be amazed how many folks in the computer audio hobby, on these threads, have no idea what DoP is (and then spread that ignorance/misconception...most calling it a PCM conversion, some calling it a USB only vehicle, etc), even though it has been explained hundreds of times over the 3 years it has been in existence.

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Isn't that due to DSD's sensitivity to DC offset or bad rips rather than anything specific to DoP?

 

No, it is because DAC needs to maintain fairly long look-ahead buffer so that it knows well in advance when switch between DSD and PCM is going to happen. Otherwise it is caught pants-down. And it doesn't know what is going to come before data starts flowing. In some cases this is not implemented very well and as a result the DAC will play some amount of PCM as DSD or some amount of DSD as PCM, or doesn't engage output mute properly when switching between the two modes. Many DAC chips WILL output spurious noises during the switch so the output MUST be muted during the switch (it is like DAC chip reboot).

 

Native ASIO DSD makes this much simpler, because there the DAC can already know what is going to come before any audio data begins to flow.

 

Second reason to prefer ASIO DSD over DoP is that ASIO driver can clearly tell whether the DAC supports PCM or DSD and which rates are supported for each. The two rate sets are completely independent. So it allows you to design a DSD-only DAC and the player application would immediately know that there's no support for PCM at all. With DoP, there's only information about PCM capabilities, but nothing that would tell anything about DSD capabilities. For example if you have a DAC that can support max 192 kHz sampling rate with PCM, but can support DSD256 with DSD, there's no problem of telling this to the player application on ASIO. But with DoP you need DAC to support 705.6/768k "PCM" in order to support DSD256, but nothing tells that the DAC can only accept 192 kHz PCM.

 

Third reason for pro-ASIO is when you would like to do recording. With DoP there's no standard mechanism to tell the ADC that it should send PCM or DSD. While with ASIO again you can tell the ADC which one you want, before any audio data is moved.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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Huh? Are you saying that those same DACs do just fine switching between ASIO DSD and PCM? I don't think DoP is the culprit, but instead the switching of formats and the dc offset issues, etc (as Skeptic has pointed out as well).

 

I don't think there are DC offset issues, or the same issues can naturally happen with PCM too. It is just about having the DAC engage it's mute circuitry before switching the mode, waiting for the output to settle and then disengaging the mute circuitry after the switch.

 

If DC is an issue, then the output should have DC-blocking capacitors or a DC-servo to deal with it, and have long enough mute period. SACD specification recommends about 200 ms.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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What I am getting out of this is that no one is challenging the SQ of the music itself, it seems that some have had bad experiences with pops and clicks and THAT'S their DoP deal breaker.

 

Miska - thanks for the insight from an implementor's point of view. When I read the summary explanation provided above it seemed like the "DoP mask" was a very simple and light implementation. Your insight explains some of the devilish details as well as why some people are getting pops and clicks.

 

I guess the real concern to look for is a native DSD ASIO driver (which both my DACs have thus the reason I've never experienced clicks and pops and can play native DSD or DoP). Seems like anyone looking to purchase a DSD compatible DAC should investigate the manufacturer's drivers prior to purchase.

Analog: Koetsu Rosewood > VPI Aries 3 w/SDS > EAR 834P > EAR 834L: Audiodesk cleaner

Digital Fun: DAS > CAPS v3 w/LPS (JRMC) SOtM USB > Lynx Hilo > EAR 834L

Digital Serious: DAS > CAPS v3 w/LPS (HQPlayer) Ethernet > SMS-100 NAA > Lampi DSD L4 G5 > EAR 834L

Digital Disc: Oppo BDP 95 > EAR 834L

Output: EAR 834L > Xilica XP4080 DSP > Odessey Stratos Mono Extreme > Legacy Aeris

Phones: EAR 834L > Little Dot Mk ii > Senheiser HD 800

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Miska, Your explanations are very good, thanks. I will reiterate though, that Dop vs ASIO is not a differentiator for the aforementioned format switching POP...it is about the DAC not muting enough (or what I referred to as format changes). So you don't think dc offset is involved in DSD playback? I've had more than one DSD dac that let a LOT of dc through, shutting down my amps (Modwright amps do not block dc but are brutally protected). One was a modification, one was a chipless design.

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Since Apple does not allow anything but PCM to go through it's CoreAudio, DoP was invented to trick the OS that PCM data is being used. Now that Apple allows ASIO like drives to pass native DSD, DoP will eventually die. With a properly designed DAC and audio player, no pops should be audible.

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Since Apple does not allow anything but PCM to go through it's CoreAudio, DoP was invented to trick the OS that PCM data is being used. Now that Apple allows ASIO like drives to pass native DSD, DoP will eventually die. With a properly designed DAC and audio player, no pops should be audible.

 

There are some popular DACs like the Luxman DA-06, Grace Design m930 that I can think of top of my head that only accept DSD via DoP. There would be more. Auralic Aries, and the Aurender X series media servers outputs only DSD via DoP.

So DoP will stay around for a while yet.

AS Profile Equipment List        Say NO to MQA

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There are some popular DACs like the Luxman DA-06, Grace Design m930 that I can think of top of my head that only accept DSD via DoP. There would be more. Auralic Aries, and the Aurender X series media servers outputs only DSD via DoP.

So DoP will stay around for a while yet.

 

And these cannot be changed with updated software? That seems quite a pity. ASIO wasn't born yesterday. I'm not saying writing an ASIO driver for a given device is easy, but that it should have been anticipated. ASIO does work well in demanding environments; a few days with Samplitude will illustrate how well recording and mastering software can work.

 

I heard somewhere that DoP extracts a heavy computational penalty in some cases. It seems that it shouldn't take too much power to pack and unpack DSD information in PCM frames (if that's what the units are called), but could someone remind us? Thanks.

Mac Mini 2012 with 2.3 GHz i5 CPU and 16GB RAM running newest OS10.9x and Signalyst HQ Player software (occasionally JRMC), ethernet to Cisco SG100-08 GigE switch, ethernet to SOtM SMS100 Miniserver in audio room, sending via short 1/2 meter AQ Cinnamon USB to Oppo 105D, feeding balanced outputs to 2x Bel Canto S300 amps which vertically biamp ATC SCM20SL speakers, 2x Velodyne DD12+ subs. Each side is mounted vertically on 3-tiered Sound Anchor ADJ2 stands: ATC (top), amp (middle), sub (bottom), Mogami, Koala, Nordost, Mosaic cables, split at the preamp outputs with splitters. All transducers are thoroughly and lovingly time aligned for the listening position.

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I heard somewhere that DoP extracts a heavy computational penalty in some cases. It seems that it shouldn't take too much power to pack and unpack DSD information in PCM frames (if that's what the units are called), but could someone remind us? Thanks.

 

I'm not doubting your claim but if you read what DoP actually is (posted at the top of this thread) you would have to question why it is CPU intensive. It's not even multiplication or division, mere less some complex algorithm, it's just simple addition and subtraction (add DSD markers, which are just markers, no dependency on the music - or subtract said markers).

Analog: Koetsu Rosewood > VPI Aries 3 w/SDS > EAR 834P > EAR 834L: Audiodesk cleaner

Digital Fun: DAS > CAPS v3 w/LPS (JRMC) SOtM USB > Lynx Hilo > EAR 834L

Digital Serious: DAS > CAPS v3 w/LPS (HQPlayer) Ethernet > SMS-100 NAA > Lampi DSD L4 G5 > EAR 834L

Digital Disc: Oppo BDP 95 > EAR 834L

Output: EAR 834L > Xilica XP4080 DSP > Odessey Stratos Mono Extreme > Legacy Aeris

Phones: EAR 834L > Little Dot Mk ii > Senheiser HD 800

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Miska, Your explanations are very good, thanks. I will reiterate though, that Dop vs ASIO is not a differentiator for the aforementioned format switching POP...it is about the DAC not muting enough (or what I referred to as format changes). So you don't think dc offset is involved in DSD playback? I've had more than one DSD dac that let a LOT of dc through, shutting down my amps (Modwright amps do not block dc but are brutally protected). One was a modification, one was a chipless design.

 

So it's more than just the driver. It appears that you are basically rolling dice (gambling) unless you hear the DAC you are interested in in your home - good luck with that. I had heard my Lampi at a show, but that was HIS setup and I have no idea what it took to get it there. I guess I am VERY LUCKY that my DAC doesn't have the pops and clicks - that's quite a gamble considering the price - whew.

 

Perhaps we should so a service for all CA members and post results for pops and clicks (brand |model | pop (yes or no) | click (yes or no)) - as a warning to others.

Analog: Koetsu Rosewood > VPI Aries 3 w/SDS > EAR 834P > EAR 834L: Audiodesk cleaner

Digital Fun: DAS > CAPS v3 w/LPS (JRMC) SOtM USB > Lynx Hilo > EAR 834L

Digital Serious: DAS > CAPS v3 w/LPS (HQPlayer) Ethernet > SMS-100 NAA > Lampi DSD L4 G5 > EAR 834L

Digital Disc: Oppo BDP 95 > EAR 834L

Output: EAR 834L > Xilica XP4080 DSP > Odessey Stratos Mono Extreme > Legacy Aeris

Phones: EAR 834L > Little Dot Mk ii > Senheiser HD 800

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With my Mytek 192 DSD DAC over USB, it seems to definitely be a driver issue (Windows 7/JRiver/ ASIO). Some driver updates I get the clicks when the format changes between tracks, and the next update it goes away. Or vice versa. Changing the various settings in JRiver doesn't seem to have any effect.

Main listening (small home office):

Main setup: Surge protector +_iFi  AC iPurifiers >Isol-8 Mini sub Axis Power Conditioning+Isolation>QuietPC Low Noise Server>Roon (Audiolense DRC)>Stack Audio Link II>Kii Control>Kii Three >GIK Room Treatments.

Secondary Listening: Server with Audiolense RC>RPi4 or analog>Matrix Element i Streamer/DAC (XLR)+Schiit Freya>Kii Three .

Bedroom: SBTouch to Cambridge Soundworks Desktop Setup.
Living Room/Kitchen: Ropieee (RPi3b+ with touchscreen) + Schiit Modi3E to a pair of Morel Hogtalare. 

All absolute statements about audio are false :)

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There are some popular DACs like the Luxman DA-06, Grace Design m930 that I can think of top of my head that only accept DSD via DoP. There would be more. Auralic Aries, and the Aurender X series media servers outputs only DSD via DoP.

So DoP will stay around for a while yet.

 

I'm sure DoP will be around for awhile, but some of the manufacturers are moving ahead with options. Folks like Auralic will have an ALSA capability in the Aries somewhere down the road, so DoP will not be their only choice. I'm sure the smart folks at Aurender can do the same (I have their X100L and will ask).

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I heard somewhere that DoP extracts a heavy computational penalty in some cases. It seems that it shouldn't take too much power to pack and unpack DSD information in PCM frames (if that's what the units are called), but could someone remind us? Thanks.

There is no heavy penalty for computation, but the packaging of DSD within PCM frames does create an overhead in terms of data usage/transfer especially where an interface is limited to 32bit.

 

If you read the DoP on Standard guide, you can see that for DSD64 for every 16 bits of data, another 8 bits need to be transferred. Each time you increase the DSD rate this is doubled - so for DSD128 its 32bits of data and 16bits of headers (requiring 24/352.8 PCM), DSD256 would require PCM rate of 24/705.6; and for DSD512 you would have to support 24/1411.2

 

With Navive DSD the transfer rates are much lower (by 1/3).

 

As Mbits/sec...

DSD rate   Bitrate (M)     DoP Bitrate (Mbits/sec)
DSD64   -  2.8224          4.2336
DSD128  -  5.6448          8.4672
DSD256  - 11.2896         16.9344
DSD512  - 22.5792         33.8688

 

Eloise

 

PS. thats my armchair engineering hat on... I'm sure the explanation isn't perfect but hopefully you get the idea!

Eloise

---

...in my opinion / experience...

While I agree "Everything may matter" working out what actually affects the sound is a trickier thing.

And I agree "Trust your ears" but equally don't allow them to fool you - trust them with a bit of skepticism.

keep your mind open... But mind your brain doesn't fall out.

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There are some popular DACs like the Luxman DA-06, Grace Design m930 that I can think of top of my head that only accept DSD via DoP.

 

That is incorrect for the Luxman. The Luxman DA-06 comes with an ASIO driver for Windows and is intended for use with ASIO and direct DSD.

 

In his review of the DA-06, Chris C wrote, "It's also possible to use JRiver Media Center's WASAPI output mode with DoP rather than the ASIO driver". However, I don't know why one would choose to do so.

"Relax, it's only hi-fi. There's never been a hi-fi emergency." - Roy Hall

"Not everything that can be counted counts, and not everything that counts can be counted." - William Bruce Cameron

 

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I'm sure DoP will be around for awhile, but some of the manufacturers are moving ahead with options. Folks like Auralic will have an ALSA capability in the Aries somewhere down the road, so DoP will not be their only choice. I'm sure the smart folks at Aurender can do the same (I have their X100L and will ask).

 

If the DAC has support for UAC2, then it will be supported by ALSA. Sending DSD as DoP is relevant to the application (audio player), not the kernel. Since ARIES runs Linux and ALSA, the support is inherited in the design.

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If the DAC has support for UAC2, then it will be supported by ALSA. Sending DSD as DoP is relevant to the application (audio player), not the kernel. Since ARIES runs Linux and ALSA, the support is inherited in the design.

Does not the DAC need a specific DSD capable ALAC driver rather than a generic UAC2 driver to support "native" DSD via ALAC?

Eloise

---

...in my opinion / experience...

While I agree "Everything may matter" working out what actually affects the sound is a trickier thing.

And I agree "Trust your ears" but equally don't allow them to fool you - trust them with a bit of skepticism.

keep your mind open... But mind your brain doesn't fall out.

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Your post does not make sense. There is no such thing as ALAC driver. ALAC is a PCM format like FLAC, WAV, APE, etc... When you play a dsf file, you can either use DoP or send it native, it all depends on the application you use to play music. On the DAC side, you need to ensure that it will support whatever format you send to it. A DAC that supports DoP not necessarily will support native.

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