What's the best DAC digital interface possible?

audio.bill

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It's my understanding that DSD via DoP using SPDIF connections (coaxial RCA/BNC, or AES/EBU) is limited to single rate DSD (DSD64), and that higher rate DSD via DoP requires USB transmission. There may be some implementations that are able to avoid this limitation, but it's the case for the majority of DACs. I'm sure someone here will correct me if I'm wrong!
 

cjf

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Nov 19, 2012
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I think the answer here other then SD Card within the DAC is Fiber Optic but I haven't seen anyone yet use it as an Input on the DAC end directly. The problem with SD direct is that you start to introduce more "stuff" into a component that is known to be sensitive to added noise and the additional activity that this "stuff" generates in terms of grunge.

Anytime time you can eliminate cables your doing yourself a favor for sure but if a cable is needed I would much rather have that cable be fiber then anything else. Maybe someday! The Holy Grail for me would be Fiber out from media server, Direct to fiber in on DAC.
 
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cjf

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Nov 19, 2012
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It's my understanding that DSD via DoP using SPDIF connections (coaxial RCA/BNC, or AES/EBU) is limited to single rate DSD (DSD64), and that higher rate DSD via DoP requires USB transmission. There may be some implementations that are able to avoid this limitation, but it's the case for the majority of DACs. I'm sure someone here will correct me if I'm wrong!

I wasn't aware that DOP was needed for an SPDIF connection. Thought is was for USB only but have been wrong before
 

audio.bill

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I didn't say that DoP was needed for DSD over an SPDIF connection, but that when it is used I believe it is limited to DSD64.
Update: Apparently according to Blizzard in post #28 DoP is required to transmit DSD64 via SPDIF. (I wasn't sure of that myself.)
 
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Blizzard

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Hi Blizzard,

Thank you for the reply. I've thought and continue to believe, perhaps...erroneosly, that DSD over PCM, i.e., DoP, is sort of a kludge. My preference is to see properly implemented SDIF-3 solutions for DSD signal exchange between DSD gear. I'm currently using a laptop with JRMC 21 to send DSD over PCM, via USB cable, to a Grace Design m905. I can lock onto DSD64, but
as yet cannot lock onto DSD128. The USB cable is ~15', perhaps too long? :confused:

Thanks for the link, too. :)

No problem. I'm not sure what the problem could be. I'm not familiar with that DAC. That is a pretty long cable though, I'd try a shorter one.
 

Blizzard

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It's my understanding that DSD via DoP using SPDIF connections (coaxial RCA/BNC, or AES/EBU) is limited to single rate DSD (DSD64), and that higher rate DSD via DoP requires USB transmission. There may be some implementations that are able to avoid this limitation, but it's the case for the majority of DACs. I'm sure someone here will correct me if I'm wrong!

Yes any higher would require too much bandwidth. So you need either USB, I2S/DSD over LVDS/CMOS, or an internal Ethernet renderer.
 

Blizzard

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I think the answer here other then SD Card within the DAC is Fiber Optic but I haven't seen anyone yet use it as an Input on the DAC end directly. The problem with SD direct is that you start to introduce more "stuff" into a component that is known to be sensitive to added noise and the additional activity that this "stuff" generates in terms of grunge.

Anytime time you can eliminate cables your doing yourself a favor for sure but if a cable is needed I would much rather have that cable be fiber then anything else. Maybe someday! The Holy Grail for me would be Fiber out from media server, Direct to fiber in on DAC.

You can do that today. You just need one of the dozens of DAC's on the market with internal Ethernet renderers.

Just use 1 of these on your router end, and another one at the receiving end right at the DAC Ethernet input. But I would power the one on the DAC end with a low noise linear supply. 70km without loss with single mode!

https://www.perle.com/products/gigabit-media-converters.shtml
 

Blizzard

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I wasn't aware that DOP was needed for an SPDIF connection. Thought is was for USB only but have been wrong before

It is if you want to send DSD 64 down it. That and a transport/DAC combo compatible.
 

cjf

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Nov 19, 2012
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You can do that today. You just need one of the dozens of DAC's on the market with internal Ethernet renderers.

Just use 1 of these on your router end, and another one at the receiving end right at the DAC Ethernet input. But I would power the one on the DAC end with a low noise linear supply. 70km without loss with single mode!

https://www.perle.com/products/gigabit-media-converters.shtml

Well this isn't exactly what I had in mind. Surely there are plenty of external doodads that one can buy and make something do what it wasn't intitialy intended to do but all your doing in the process is adding more things to the signal path.

I am talking about a native Fiber connection on the DAC Input coming from what could be a Fiber HBA card on the music server end. No external boxes, extra power supplies, battery packs or other crap needed along the way.
 

Blizzard

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Well this isn't exactly what I had in mind. Surely there are plenty of external doodads that one can buy and make something do what it wasn't intitialy intended to do but all your doing in the process is adding more things to the signal path.

I am talking about a native Fiber connection on the DAC Input coming from what could be a Fiber HBA card on the music server end. No external boxes, extra power supplies, battery packs or other crap needed along the way.

Well the signal needs to be converted back to copper at some point. It could be built into the box by the manufacturer, or external. Being external does isolate the circuitry from the sensitive internal DAC components. So probably even better. I can assure you that converters/transceivers create much more noise than a low profile SD card reader.
 

Groucho

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Aug 18, 2012
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...all your doing in the process is adding more things to the signal path.

An interesting concept in the context of digital audio. If you are streaming over the internet, you have no way of knowing how many hundreds of switches, routers, converters, junctions there are. They are not made of audiophile-approved materials. Their power supplies are probably switched mode and maybe don't even have gold connections. The routing is probably changing dynamically all the time. The data may even have been beamed into space and back. Is anyone arguing that 10 "doodads" (I like that word) in the digital path are inaudible, but that 100 are audible? How about 1000? Or 10,000? Surely at times, internet streaming would be unlistenably bad.

In fact, we will never know how many doodads there are, and we will never be able to hear, or measure a difference. When it comes to packet-based digital audio, there is no "signal path". This only applies in the analogue world. The digital stream is completely different. It is not in the signal path. Sure there may be analogue noise etc. induced after the final node, but it is basic engineering to solve this (not that all DACs will be perfect in this regard).
 

Blizzard

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An interesting concept in the context of digital audio. If you are streaming over the internet, you have no way of knowing how many hundreds of switches, routers, converters, junctions there are. They are not made of audiophile-approved materials. Their power supplies are probably switched mode and maybe don't even have gold connections. The routing is probably changing dynamically all the time. The data may even have been beamed into space and back. Is anyone arguing that 10 "doodads" (I like that word) in the digital path are inaudible, but that 100 are audible? How about 1000? Or 10,000? Surely at times, internet streaming would be unlistenably bad.

In fact, we will never know how many doodads there are, and we will never be able to hear, or measure a difference. When it comes to packet-based digital audio, there is no "signal path". This only applies in the analogue world. The digital stream is completely different. It is not in the signal path. Sure there may be analogue noise etc. induced after the final node, but it is basic engineering to solve this (not that all DACs will be perfect in this regard).

It doesn't matter as long as the data is intact once it arrives in your transport. There's no clock being sent when it's just a data file, so no jitter can be introduced. However it does matter in the process of sending it from your transport to your DAC chip. Unless you don't believe jitter and noise is real. DAC's with internal Ethernet renderers have the advantage that it's still un-clocked data until it arrives at the renderer chip in the DAC. However you still need to worry about transmitting noise from any device in the signal path that's physically connected to the DAC.
 

Blizzard

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Blizzard

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Unfortunately this is the only way. SDIF/3 -> ST-optical

I'll be working on something similar for audiophile grade Ethernet transmission. Does a clock PLL get sent over the ST fiber, or is it sent over a separate connection?
 

ack

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May 6, 2010
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Hi Guys,


I've posted on a few other threads a few of my thoughts on DAC interfaces. This topic has been of particular interest to me over the last year. I have extensively researched most known protocols. I've learn't a lot along this journey. I used to think that USB was the holy grail. But to my surprise, it can actually one of the worst. As of today, this is how I have it figured from best to worst of the most common protocols. Yes I know, how each protocol is implemented is extremely important. But what I'm referring to is if cost was no object, and the finest implementations of each protocol were built.

1: Internal SD card interface.
2: Internal Ethernet renderer
3: I2S/DSD over LVDS or CMOS over short distances.
4: AES/EBU
5: Coaxial SPDIF
6: USB
7: Toslink

I have also heard ST fibre like Bel Canto uses can also be great. But I don't know enough about it now to include on the list.

If anyone agrees or disagrees with my findings, please chime in. Then we can start diving into details of each protocol.

Thanks,
Blizzard.

I just read the whole thread; you have summed it up pretty well above. I hope people will realize how bad USB - even Async - really is for audio. Thankfully, there are devices like the Berkeley Alpha USB to alleviate the pain, but it's still not the same. From a technical perspective, I really like the Baetis Reference server which bypasses USB to give you AES/ABU from the S/PDIF stream. If it only were priced reasonably...
 

Blizzard

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I just read the whole thread; you have summed it up pretty well above. I hope people will realize how bad USB - even Async - really is for audio. Thankfully, there are devices like the Berkeley Alpha USB to alleviate the pain, but it's still not the same. From a technical perspective, I really like the Baetis Reference server which bypasses USB to give you AES/ABU from the S/PDIF stream. If it only were priced reasonably...

Yes many better alternatives out there to USB. Not sure why everyone has such a hard time realizing it.
 

Mike Lavigne

Member Sponsor & WBF Founding Member
Apr 25, 2010
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Yes many better alternatives out there to USB. Not sure why everyone has such a hard time realizing it.

when alternative digital interfaces are in the best sounding dacs then the market will go there. users are not driving this, dac makers are.

I'm interface agnostic. but if my Trinity and GG are the best sounding dacs, and they use USB, then I'm using USB. let my ears hear better, i'll be drawn to that better sound with whatever interface it has. my 17 terabytes of music don't care the path they take to the dac.

I'm speaking at the tip top dac performance of the market here. I know that there are all kinds of dacs and all sorts of interfaces.
 

Blizzard

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Reading the white paper on the Bel Canto Black system, it appears the ST fiber does send a clock. However they reclock the signal on the DAC/amp end. This shows that jitter is introduced by the transceivers. It's great that all of the DSP engine and I/O is isolated in a seperate box, but I do think only having 1 clock in the system has advantages still.

http://www.belcantodesign.com/black/downloads/Bel Canto BLACK White Paper.pdf
 

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