Study: Is I²S interface better for DACs than S/PDIF or USB?

[sarumbear]

It's not a standard published by the IEC, IEEE, or similar organisation. It's still open and the de facto standard for interconnecting audio ICs.

I was talking about the use of I2S to transfer data between devices. I2S was never a standard for that whatever way you define the word. I2S is designed as an IC to IC communication method. There is no explanation how to implement buffers which you need to feed a cable. Nor there is a standard connector.

As clock and data are separate and distances involved are much larger than an IC to IC implantation, any delay difference between the two will cause issues. Nothing on Philips’ spec covers such transport issues.

It is a concoction of a few manufacturers.

 

[mansr]

I was talking about the use of I2S data transfer between devices. That was never a standard whatever way you define the word. I2S is designed as an IC to IC communication method. There is no explanation how to implant buffers which is required to feed cables. Nor there is a standard connector.

That's what I said.

 

[Veri]

Actually the only advantage of I2S and USB over SPDIF is the ability to carry DSD native and higher PCM resolution than 24/192.

An advantage yes, but nothing a straight USB connection couldn't do as well right?

 

[sarumbear]

That's what I said.

Which means I2S is not a standard to be used connecting devices as it is not a device interconnect standard.

 

[Veri]

Which means I2S is not a standard to be used connecting devices as it is not a device interconnect standard.

note that mansr is not against your stance/pov whatsoever

 

[mansr]

Which means I2S is not a standard to be used connecting devices as it is not a device interconnect standard.

Why are you so argumentative?

 

[Roland68]

Which means I2S is not a standard to be used connecting devices as it is not a device interconnect standard.

Of course, i2s is a globally recognized standard. It was introduced as a standard by Philips in 1986 and has established itself as the standard through its use in thousands or tens of thousands of CD players.

But the discussion in this thread is not about the normal i2s connection, but about the external connection via the LVDS industry standard.
LVDS is an interface standard for high-speed data transmission of the physical layer, in which neither cables nor connectors are specified. It was created, among other things, to transmit standardized connections between ICs (various standards or bus systems) on short cable routes.
Of course, a manufacturer can decide for himself which cable, connector and assignment to use. That is then its standard and it does not have to be compatible with anything.

I already have various source devices (CD player, USB-> i2s converter, etc.) and DACs (e.g. Gustard, SMSL, Topping, DIY DAC i2s boards, CD players DAC boards, etc.) with several i2s -> LVDS and LVDS -> i2s converters connected.
Therefore I can say that the manufacturers of the devices with external i2s over LVDS interfaces adhere to their respective standards.

 

[sarumbear]

Of course, i2s is a globally recognized standard. It was introduced as a standard by Philips in 1986 and has established itself as the standard through its use in thousands or tens of thousands of CD players.

But the discussion in this thread is not about the normal i2s connection, but about the external connection via the LVDS industry standard.
LVDS is an interface standard for high-speed data transmission of the physical layer, in which neither cables nor connectors are specified. It was created, among other things, to transmit standardized connections between ICs (various standards or bus systems) on short cable routes.
Of course, a manufacturer can decide for himself which cable, connector and assignment to use. That is then its standard and it does not have to be compatible with anything.

I already have various source devices (CD player, USB-> i2s converter, etc.) and DACs (e.g. Gustard, SMSL, Topping, DIY DAC i2s boards, CD players DAC boards, etc.) with several i2s -> LVDS and LVDS -> i2s converters connected.
Therefore I can say that the manufacturers of the devices with external i2s over LVDS interfaces adhere to their respective standards.

In other words those standards are a mess and shouldn’t be used. What type a standard LVDS is that it doesn’t even define a connector?

 

[mansr]

In other words those standards are a mess and shouldn’t be used. What type a standard LVDS is that it doesn’t even define a connector?

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[Roland68]

In other words those standards are a mess and shouldn’t be used. What type a standard LVDS is that it doesn’t even define a connector?

Again, the LVDS standard is a purely physical transmission layer! It is only responsible for the standardized transmission, not for the cables or plugs used.

Standards have always been used to exclude "others" or to establish one's own, or both. Unfortunately, this is not very customer-friendly, but unfortunately it is also common practice.
Many devices follow the standards that Topping, Gustard, SMSL (Sabaj, Loxjie), Xingser and Audio-GD also use, or can be switched accordingly (most devices can be switched between 4-6 standards). LKS, Holo and PS Audio can also usually be operated.
Devices that do not follow any of these connector / assignment standards can usually be connected with special cables, but they can also simply be ignored.

For the fact that it is not an officially standardized standard, it works very well. It's just a very direct connection that leaves a lot of possibilities open (also for future devices) and is very little regulated.
With appropriate background knowledge, you can tap the i2s signal directly on the board of a player and transfer it to a DAC with an LVDS converter, just one of many examples.

And if one does not like this standard or is too "non-standardized", simply do not use it.
I think the possibilities of i2s over LVDS are great, precisely because it is so open and I like to use it.

 

[sarumbear]

Again, the LVDS standard is a purely physical transmission layer! It is only responsible for the standardized transmission, not for the cables or plugs used.

I think the possibilities of i2s over LVDS are great, precisely because it is so open and I like to use it.

Physical surely should include the connector.

What is closed about SPDIF or USB?

 

[sarumbear]

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It just proves that it is a not a complete standard.

It is intended that this Standard will be referenced by other standards that specify the complete interface (i.e., connector, pin assignments, function)

 

[sq225917]

I2s is not an external device connection standard, it's merely an on-pcb data transmission protocol. Connections aren't specified because it was intended to be done across pcb traces only, not connectors and not as an external interface.

Any i2s across connectors or external plugs is beyond the scope of the original protocol.

 

[Roland68]

I2s is not an external device connection standard, it's merely an on-pcb data transmission protocol. Connections aren't specified because it was intended to be done across pcb traces only, not connectors and not as an external interface.

Any i2s across connectors or external plugs is beyond the scope of the original protocol.

You are absolutely right, I am not aware of any devices that transmit the normal i2s signals (4 - 5 contacts) externally.

 

[sarumbear]

I2s is not an external device connection standard, it's merely an on-pcb data transmission protocol. Connections aren't specified because it was intended to be done across pcb traces only, not connectors and not as an external interface.

Any i2s across connectors or external plugs is beyond the scope of the original protocol.

Then saying and labelling it on top of a socket as I2S is plain wrong. Cables, connectors and buffers are not defined but the data happens to obey an inter IC protocol that was once designed by a chip manufacturer. It is not a standard it is "look what a concocted if you also concoct we may communicate". One may argue that this is how open standards develop, but that is not the case here. There is no agreement of buffers, cable type, sockets, etc. written down and agreed by more than one manufacturer. Everyone use a different method.

Once again: I2S is not a device to device connection standard. What we see on some devices are custom implementations of "a" protocol. Nobody should care nor rely on it.

 

[mansr]

Then saying and labelling it on top of a socket as I2S is plain wrong.

Exactly that. One might just as well put that label on an S/PDIF input. They both use a receiver chip that converts whatever is on the wire into I2S, after all.

 

[Roland68]

Then saying and labelling it on top of a socket as I2S is plain wrong. Cables, connectors and buffers are not defined but the data happens to obey an inter IC protocol that was once designed by a manufacturer. It is not a standard it is "look what a concocted if you also concoct we may communicate". One may argue that this is how open standards develop, but that is not the case here. There is no agreement of buffers, cable type, sockets, etc. written down and agreed by more than one manufacturer. Everyone use a different method.

Once again: I2S is not a device to device connection standard. What we see on some devices are custom implementations of "a" protocol. Nobody should care nor rely on it.

Much too late; o)
There are thousands of satisfied users of i2s over LVDS worldwide. Alone the whole users of the digital USB converters from Gustard, Xingser, Audio GD etc., plus many streamers and DAP with this interface (and there are more and more).
In addition, there are now thousands of i2s -> HDMI (LVDS) and HDMI (LVDS) -> i2s modules from the DIY sector that have been sold. The number of available modules has increased tenfold in the last 2 years. There are also many special modules for individual solutions.

And yes, i2s is only intended for internal data transmission and is not used in any other way.
And LVDS is the standard that was developed precisely for such applications to enable external data transmission over short cable routes.
And LVDS is also the world's most common standard for this type of data transmission, both in industry and in computer technology and consumer electronics.

I understand from your signature that you should be familiar with the layer models. The LVDS standard works on the physical layer and therefore allows cable connections where only short connections via conductor paths are actually possible. These LVDS connections are "invisible" to the application and that is the trick. Therefore nothing else is required, not even buffers.
It should also be clear why the LVDS standard may not contain any specifications about cables or plugs, because it would then be unusable and superfluous.

With LVDS, audio manufacturers have chosen exactly the standard that was created to enable external transmission for standards such as i2s.
Over 95% of the devices on the market with this interface can be connected and operated with a standard HDMI 2.0 cable.
This is also no worse than USB 3.0 when it was first introduced, where, despite the extremely high level of standardization, there were problems with almost every second device at the beginning.

 

[mansr]

There are thousands of satisfied users of i2s over LVDS worldwide.

I prefer I2S over USB.

 

[pkane]

Once again: I2S is not a device to device connection standard. What we see on some devices are custom implementations of "a" protocol. Nobody should care nor rely on it.

One of the earliest examples of external I2S I know of (and had used) was in Audio Alchemy gear in mid 90's. It was on a mini-DIN type connector (diagram from Sonore's Jesus Rodriguez spreadsheet of known I2S connectors). This format made into a few products by other companies, as well, and even inspired some "improved audiophile" versions of I2S silver cables, IIRC:

 

[Roland68]

Exactly that. One might just as well put that label on an S/PDIF input. They both use a receiver chip that converts whatever is on the wire into I2S, after all.

The i2s signal is not changed or interleaved during transmission, all channels are retained. Only a differential signal is generated in order to minimize errors in the transmission.
In addition, there is the transmission of a maximum of PCM 1536KHz and DSD1024.