I2S - SPDIF - Clock Jitter

[Maximiliano2]

My questions concern the I2S. I tried to find some answers, but it seems so obvious to those who speak it is impossible to see it in black and white. Throughout my readings on this forum and elsewhere is what I understood:

• The I2S is a standard digital transmission of sound, just like the popular S / PDIF and noble DSD.
• But it seems that I2S is greater than the S / PDIF in particular with respect to jitter, which seems eliminated. Why?
• The I2S is a synchronous link (no need to regenerate the PLL clock, or need a second clock ...)
• In the very high end, we preferred to use a master clock that synchronizes all (synchronous digital link is and it is unnecessary to reconstruct the clock)

It seems clear that enable I2S happened inconvenience mismatches and thus jitter clocks. But then ... I again have some queries :

• Why I2S is not THE standard?
• What transport today "issue" in I2S?
• What are the bits and frequencies supported?
• Which includes I2S DAC?
• What connections are necessary?

Please try to explain me in details.

[Abigail101]

It seems that the I2S provides a clock signal in parallel data. I understand that it is necessary to synchronize various elements in the studio but for restitution where there is only one element involved, ie the source or the DAC, what is the value of the clock "perfect"? And our ears can detect it a few nanoseconds desynchronizations .... ? As for the perception ... Is it the absence of jitter which is about + clarity and depth, ventilation and microinformation.

[Maximiliano2]

My obsession (shared by many) for zero jitter may be unfounded. But I say: Let us solve the problem of jitter, to be sure, we will tackle the rest later. For if the search does nothing, we can say that it can not degrade the sound. And I go back to I2S, do you know a little more? Until now I thought that I had perhaps a SPDIF DAC coupled to a clock in space to remove Jitter. Or it might just be the standard I2S. In fact I read that the next transport PSAudio would connect with the next DAC in I2S the same brand "which is jitter free" (and HDMI to boot!). Then suddenly an alternative point the tip of its nose, and I'd like to know if this is an effect of marketing or a real solution.

[Umberto-Micro]

The I2S format is an audio data transport between internal components in a device (stereo, TV, etc.). It is never (or very rarely) used between two devices. The I2S has at least one thread with the data (audio pin Data # 3 above) and a clock (I'm not sure what clock among the pine trees # 1, # 2 or # 4). Thus 2 son more mass (neutral). This internal standard is less easy to convey that the S / PDIF him, consists of only a single thread + 1 mass. (Impedance 75ohm coax cable is a single, very simple to this fact). Since I have a cable connection and this couple with i2s, suddenly I do not know if it's the cable that is my HS or connectors. Here is the connector:

[Daniela007]

In the case of S / PDIF the clock must be extracted from the data stream since there is no specific signal. PLL (Phase Lock Loop) circuit DAC is responsible mining that job. Depending on the quality of the PLL, the accuracy of the extracted clock is more or less good ... With the I2S clock is independent but if it is of poor quality, not better or worse in fact. I2S flow is not free of jitter as any digital signal has jitter. Jitter is a time shift at the rising edge (or lowering) the digital signal. So the 0 or 1 arrive a bit early or a tad late. It is clear that an external clock (if it is, itself, very clean with low intrinsic jitter) will be beneficial to put all data on exactly the right timing. But a good DAC which uses an input buffer sophisticated as my Lavry DA10 will also be able to do an excellent job on the signal S / PDIF and compensate for the jitter of the digital stream. More reasons to have / create jitter will also play in the internal device (do not forget that we are talking about pico second, the worst of nano seconds ...). The I2S is not a panacea (if the pros would use). And it requires a clock signal of HIGH quality between devices. It can be so easy to degrade a signal (a simple mismatch of impedance ...). That is why it is confined internally or all of transmission remains more controllable by the designer / manufacturer.