different audio in digital output

[poriya]

Hello everyone..

I have question about blurays or cd players devices wich responsible for just having audio digital output (Not analoge)...The question is in term of digital signal are there any differences between devices where they just make digital audio out (and price tag shows yes there is)..because digital signals are unique (0 or 1) and all of them should do it flawless....

Thank you in advance

 

[manicm]

No real differences should be heard from the players if you're using A/V amps to decode the sound - in which case it would be down to the amplifier. If you're looking for true SACD playback these are usually only through HDMI, and ideally an amp which decodes DSD natively.

 

[mmg]

Well... yes and no: it's true that a £20 cd drive can read the 1s and 0s just as a £1000 drive can. One of this issues you can get is timing issues, which can cause jitter: if the transport doesn't supply the 1s and 0s fast enough, or if it supplies them too fast or a combination of both (and we're talking nanoseconds here), then the decoder will have to constantly re-adjust its internal clock, which will cause jitter. Here's an interesing article about this: http://www.madronadigital.com/Library/DigitalAudioJitter.html

The question remains if jitter is really audible. I think it can only be an issue on very high-end systems.

 

[MajorFubar]

I'm not suggesting jitter is all a load of pseudo-science, but I can't help but feel it's the word of the moment.

Back in the day, you apparently needed a £1,000+ CD transport because that plastic Saisho thing in Dixons with a digital output on the back wasn't reading all the data off the disc, or was reading it with billions of errors that had to be 'fudged' a bit by software (error correction), and so it couldn't possibly sound as good as a £1,000 CD transport even if you plugged it into the same DAC.

Then computer technology in the home exploded, CD ROMs drives and DVD ROMs drives came along, plummeted in price so much that they were almost given away in cereal packets, and showed that you could in fact read all the data off the disc bit-prefectly with a cheap boggo-standard flimsy drive made by the hundreds in a sweat-shop in China. And to prove it beyond doubt, they gave us EAC and XLD. Looks like that Saisho was very likely reading the disc perfectly after all...

I just can imagine the conversations down at Mega Expensive CD Transports Ltd: "Damn. Now what? How do we prove to the punters they still need to spend the price of a half-decent used car on a CD transport? Aha...Jitter! We can prove it exists, we can claim/prove that our £1,000+ drives are less prone to it than that bloody Saisho, and no one can prove that normally it's completely inaudible anyway. We're back in business boys!"

 

[andyjm]

Hello everyone..

I have question about blurays or cd players devices wich responsible for just having audio digital output (Not analoge)...The question is in term of digital signal are there any differences between devices where they just make digital audio out (and price tag shows yes there is)..because digital signals are unique (0 or 1) and all of them should do it flawless....

Thank you in advance

If your DAC / Processor is sensitive to clock jitter, then it is possible that the quality of the transport may matter. Jitter is a real effect, and the commonly used S/PDIF connection can make matters worse.

On the other hand, if your DAC / Processor has jitter mitigation circuitry (as many do these days), or uses an asynchronous interface like async USB then there should be no audible difference between a £20 drive and a £1000 shiny transport with a fancy name.

There have been many studies on the level at which jitter becomes audible. To complicate matters, jitter is a random process and not all jitter is created equal. The most easily detectable jitter is correlated in some way to the programme material. Unfortunately 'code correlated jitter' is just the type that the S/PDIF connection introduces. If you have the patience, then there are studies on the net that suggest that jitter is inaudible below 200nS rms, and others that suggest the jitter in the 10s of pS can be heard. I think a lot depends on the type of jitter being used for the study.

In an ideal world, the clock used to drive the D2A chip should be very stable, and stuck right next to the D2A chip on the circuit board. Anything else that relies on a transport in a different box, a 'sidecar' or whatever for a clock is always going to be a compromise.

 

[poriya]

Hello everyone..

I have question about blurays or cd players devices wich responsible for just having audio digital output (Not analoge)...The question is in term of digital signal are there any differences between devices where they just make digital audio out (and price tag shows yes there is)..because digital signals are unique (0 or 1) and all of them should do it flawless....

Thank you in advance

If your DAC / Processor is sensitive to clock jitter, then it is possible that the quality of the transport may matter. Jitter is a real effect, and the commonly used S/PDIF connection can make matters worse.

On the other hand, if your DAC / Processor has jitter mitigation circuitry (as many do these days), or uses an asynchronous interface like async USB then there should be no audible difference between a £20 drive and a £1000 shiny transport with a fancy name.

There have been many studies on the level at which jitter becomes audible. To complicate matters, jitter is a random process and not all jitter is created equal. The most easily detectable jitter is correlated in some way to the programme material. Unfortunately 'code correlated jitter' is just the type that the S/PDIF connection introduces. If you have the patience, then there are studies on the net that suggest that jitter is inaudible below 200nS rms, and others that suggest the jitter in the 10s of pS can be heard. I think a lot depends on the type of jitter being used for the study.

In an ideal world, the clock used to drive the D2A chip should be very stable, and stuck right next to the D2A chip on the circuit board. Anything else that relies on a transport in a different box, a 'sidecar' or whatever for a clock is always going to be a compromise.

So if we rip our albums and store it in hard drive then using usb sync,,, there is no issue at all?...save the money for decent DAC..

 

[mmg]

So if we rip our albums and store it in hard drive then using usb sync,,, there is no issue at all?...save the money for decent DAC..

Sure, but that would mean you need a PC each time you want to play music. AFAIK only PCs can use the async USB interface on a DAC.

 

[poriya]

So if we rip our albums and store it in hard drive then using usb sync,,, there is no issue at all?...save the money for decent DAC..

Sure, but that would mean you need a PC each time you want to play music. AFAIK only PCs can use the async USB interface on a DAC.

And As alternative it possible to connect the hard drive to usb port of CD-Blu ray player and get the digital output via optical port..

 

[mmg]

And As alternative it possible to connect the hard drive to usb port of CD-Blu ray player and get the digital output via optical port..

Sure that's possible but there's no advantage: you're using usb (non-async), and you're using the optical out of the Blu-Ray player. If the clock of the Blu-Ray is off you'll still have jitter issues.