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Digital transport brawler

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paulkebab

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is gonna have a hard time now, proving his technical knowledge into something tangible. And audible. Bring it on.
 

Strictly Stereo

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Jan 29, 2018
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andyjm said:
Just to clarify the discussion, a synchronous DAC slaved in some way to the previous device in the chain is a bad engineering idea.

An async DAC with its own internal clock, using some form of flow control to regulate the data fed to it is a good engineering idea.

That doesn't mean all async DACs are good, and all synchronous DACs are bad, but all other things being equal, an async DAC is certainly a better bet.

The other point to clarify, as it seems to have got a few confused, is that jitter is not cumulative in a digital system. A moments thought would point this out. Is the quality of the music downloaded from a server in Cupertino dependent on the jitter of the data server? Of course not. The jitter that matters is the jitter of the A2D converter at the start of the chain, and the jitter of the D2A converter at the end of the chain. The rest in between is irrelevant.

Which gets back to an earlier point, that with a decent async DAC, a RasPi for £35 is just as good as a Whiz Bang streamer for £10,000.
I am not arguing which type of DAC design is best here (synchronous, fully asynchronous, asynchronous USB). I have a decent grasp of the pros and cons of each design, but I know that there are fine sounding examples of each design available. I certainly understand that an asynchronous DAC (or input) will be much more forgiving of a lower quality source. However, this is about what sounds best, which will always be subjective, and so I leave room for the possibility that someone might prefer the combination of a high quality source and a synchronous DAC.

You are quite right about the regenerative nature of digital signal transmission. Cumulative was a poor choice of word. However, in your S/PDIF example, unless the DAC is fully asynchronous, jitter induced by the transport and interconnect is also going to be a factor and therefore the quality of the transport does matter. I just cannot see why you are sticking rigidly to the idea that jitter only matters inside the DA and AD converters.
 

insider9

Well-known member
Sep 20, 2016
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andyjm said:
Just to clarify the discussion, a synchronous DAC slaved in some way to the previous device in the chain is a bad engineering idea.

An async DAC with its own internal clock, using some form of flow control to regulate the data fed to it is a good engineering idea.

That doesn't mean all async DACs are good, and all synchronous DACs are bad, but all other things being equal, an async DAC is certainly a better bet.
Ok

andyjm said:
The other point to clarify, as it seems to have got a few confused, is that jitter is not cumulative in a digital system. A moments thought would point this out. Is the quality of the music downloaded from a server in Cupertino dependent on the jitter of the data server? Of course not.
So far so good.

andyjm said:
The jitter that matters is the jitter of the A2D converter at the start of the chain, and the jitter of the D2A converter at the end of the chain. The rest in between is irrelevant.
Bit in bold is dependent on data stream to DAC. Right? If so that dependecy extends to transport.

andyjm said:
Which gets back to an earlier point, that with a decent async DAC, a RasPi for £35 is just as good as a Whiz Bang streamer for £10,000.
Doesn't RasPi have a common bus for USB and Ethernet? Which from desing perspective is a bad engineering idea? ;)

Also how much does one have to spend for a decent async DAC referred to here? I understand we're talking galvanic isolation too?

By the way, Andy I'm just debating and have no agenda. I'm in fact considering building an all-in-one class D (amp/dac/streamer) and RasPi is one of the options. Any decent async balanced DAC boards that you could suggest for RasPi?
 

cheeseboy

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Jul 17, 2012
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insider9 said:
By the way, Andy I'm just debating and have no agenda. I'm in fact considering building an all-in-one class D (amp/dac/streamer) and RasPi is one of the options. Any decent async balanced DAC boards that you could suggest for RasPi?
you could do it all in one - https://www.audiophonics.fr/en/diy-dac/audiophonics-i-sabre-amp-dac-es9023-class-d-amplifier-2x30w-tpa3118-p-11800.html
 

lpv

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Mar 14, 2013
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Strictly Stereo said:
Successive studies have demonstrated that human beings can detect lower levels of jitter than previously thought.
I would be interested to see links/ references to these studies.
 

insider9

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Sep 20, 2016
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cheeseboy said:
insider9 said:
By the way, Andy I'm just debating and have no agenda. I'm in fact considering building an all-in-one class D (amp/dac/streamer) and RasPi is one of the options. Any decent async balanced DAC boards that you could suggest for RasPi?
you could do it all in one - https://www.audiophonics.fr/en/diy-dac/audiophonics-i-sabre-amp-dac-es9023-class-d-amplifier-2x30w-tpa3118-p-11800.html
Thanks for the link, but that's not much fun it's almost built :)

I'll probably start a separate thread. I'm at a research stage at present.
 

cheeseboy

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Jul 17, 2012
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insider9 said:
cheeseboy said:
insider9 said:
By the way, Andy I'm just debating and have no agenda. I'm in fact considering building an all-in-one class D (amp/dac/streamer) and RasPi is one of the options. Any decent async balanced DAC boards that you could suggest for RasPi?
you could do it all in one - https://www.audiophonics.fr/en/diy-dac/audiophonics-i-sabre-amp-dac-es9023-class-d-amplifier-2x30w-tpa3118-p-11800.html
Thanks for the link, but that's not much fun it's almost built :)

I'll probably start a separate thread. I'm at a research stage at present.
have a futher dig in to that site, they do diy kits :)
 

Strictly Stereo

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Jan 29, 2018
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paulkebab said:
is gonna have a hard time now, proving his technical knowledge into something tangible. And audible. Bring it on.
I think we are actually on the same page with the technical stuff. Andy says that asynchronous DACs are best and from an engineering standpoint and I am inclined to agree. With a fully asynchronous DAC, his statement that jitter only matters in practical (rather than theoretical) terms during the AD and DA steps is correct. However, not every DAC (or input) is asynchronous and being asynchronous is not in itself a guarantee of great sound quality or even accurate conversion. There are some very fine sounding DACs available which are synchronous or have asynchronous USB but synchronous S/PDIF inputs. Such products could be affected by jitter from the transport itself or even an incorrectly specced interconnect.

As to audibility, that is a whole other can of worms. Successive studies have demonstrated that human beings can detect lower levels of jitter than previously thought. I say try things for yourself. If you cannot hear an improvement and you have no other reason to change, stick with what you have. This applies to every component, not just to digital transports and DACs. However, when it comes to choosing transports and DACs, I do think they should be considered together, for the reasons set out above.
 

insider9

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Sep 20, 2016
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cheeseboy said:
insider9 said:
cheeseboy said:
insider9 said:
By the way, Andy I'm just debating and have no agenda. I'm in fact considering building an all-in-one class D (amp/dac/streamer) and RasPi is one of the options. Any decent async balanced DAC boards that you could suggest for RasPi?
you could do it all in one - https://www.audiophonics.fr/en/diy-dac/audiophonics-i-sabre-amp-dac-es9023-class-d-amplifier-2x30w-tpa3118-p-11800.html
Thanks for the link, but that's not much fun it's almost built :)

I'll probably start a separate thread. I'm at a research stage at present.
have a futher dig in to that site, they do diy kits :)
I know their website. Have a look at my thread. Be interested to hear your thoughts. Thanks
 

lpv

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Mar 14, 2013
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ellisdj said:
do the bits all sound the same - if they come off a cd, usb drive, hard drive nas drive or the cloud into the same dac - does it all sound the same - nope not in my experience so jitter before the dac must matter
can you also hear any of the following:

whispers

voices telling you what to do

baby crying

laughter when there is no one around

steps
 

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