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

[chris719]

I read two of you post not still don't understand what the issue

There's no issue. Some guy tried to turn fact into a philosophical argument.

 

[sumpao]

There's no issue. Some guy tried to turn fact into a philosophical argument.

Ok out of curiosity did I2S D2D converter make a different to a dac when connect with HDMI cable ?

like Gustard U16 or Singxer

 

[chris719]

Second (remember I'm coming from a cost-aware perspective), if I'm looking specifically at various R-pi HAT configurations, wouldn't a DAC HAT, sitting on the R-pi I2S, outputting directly to the amplifier, be the shortest path? Why get into further translations, S/PDIF, TOSLINK, any of that, if not necessary?

I2S is the best choice for an "intra-box" interconnect. So, yes, in most cases with a board-to-board connection like a hat, you would want to use I2S. The reason people often don't use I2S with the RPi is more of an RPi specific issue as far as I understand. There's no real downside to using another interface like USB out only to go back to I2S in terms of audio quality, it's just a kludgy solution for a one-box device.

 

[Veri]

only to go back to I2S in terms of audio quality

This entire thread posits that I2S has zero "audio quality" benefits...

 

[chris719]

This entire thread posits that I2S has zero "audio quality" benefits...

Right. k9gardner just asked why not use I2S for a RPi hat instead of some other interface. It would be perfectly suited for that application if there weren't constraints on I2S on some versions of the RPi that some designers don't like. The full sentence is describing that there are no issues "converting" between I2S and anything else.

 

[mansr]

I read your posts in this thread, thus I can firmly conclude that you have no idea what you are talking about. I'm not trying to insult you, you just don't.

Quite so. Since the I2S standard doesn't specify a cable, an "I2S cable" could refer to anything with a sufficient number of wires. There really isn't anything to argue over.

 

[chris719]

Quite so. Since the I2S standard doesn't specify a cable, an "I2S cable" could refer to anything with a sufficient number of wires. There really isn't anything to argue over.

Yeah. I almost hate referring to what PSAudio has done as I2S. It's not even electrically compatible with what is defined in the standard. I think sending it via LVDS and shielded twisted pair is perfectly fine, but look at the confusion this whole thing creates. Not that I'd be bringing I2S outside of a box in most cases, but if I did, I would have labeled it as a proprietary interface and not used HDMI cables.

 

[mansr]

Yeah. I almost hate referring to what PSAudio has done as I2S. It's not even electrically compatible with what is defined in the standard. I think sending it via LVDS and shielded twisted pair is perfectly fine, but look at the confusion this whole thing creates. Not that I'd be bringing I2S outside of a box in most cases, but if I did, I would have labeled it as a proprietary interface and not used HDMI cables.

Using HDMI cables makes sense, insofar the scheme has any sense at all (which it doesn't), since both connectors and cable assemblies are readily available at low cost. USB Type C would have been another option today. It's not unusual to repurpose existing cables for non-standard connections. As long as everything is clearly marked and mutually non-destructive if connected to standard devices, there's no problem.

 

[chris719]

Using HDMI cables makes sense, insofar the scheme has any sense at all (which it doesn't), since both connectors and cable assemblies are readily available at low cost. USB Type C would have been another option today. It's not unusual to repurpose existing cables for non-standard connections. As long as everything is clearly marked and mutually non-destructive if connected to standard devices, there's no problem.

It's not the craziest choice, but I'd probably have tried to avoid something that carries audio normally. As you say, the problem is really the entire scheme.

 

[musicapristina]

Here are the results with GPLL bypassed:

View attachment 23913

While not audible either way, jitter is worse with S/PDIF when you turn off GPLL.

I see this is listed in a comment, but not in the actual article.

 

[sumpao]

This entire thread posits that I2S has zero "audio quality" benefits...

it has

 

[NTK]

it has

Uh-huh

 

[Veri]

it has

Why would it? If for example the USB input works properly, why would you buy something to put in between just to use that I2S input? I don't see the appeal or benefit, nope.

 

[sumpao]

Why would it? If for example the USB input works properly, why would you buy something to put in between just to use that I2S input? I don't see the appeal or benefit, nope.

because it sound different

 

[Veri]

because it sound different

Right..

 

[Zog]

Why would it? If for example the USB input works properly, why would you buy something to put in between just to use that I2S input? I don't see the appeal or benefit, nope.

If you plonk a USB to I2S converter between your USB output (on your PC, say) and connect to your I2S input on your DAC then I agree that cannot have a benefit. However it is possible to have an I2S output from your PC. It requires an aftermarket product, for example the Pink Faun Audio Bridge.

 

[somebodyelse]

If you plonk a USB to I2S converter between your USB output (on your PC, say) and connect to your I2S input on your DAC then I agree that cannot have a benefit. However it is possible to have an I2S output from your PC. It requires an aftermarket product, for example the Pink Faun Audio Bridge.

If that's your intention you'll have to be careful that the PCIe card isn't using USB internally between chips. The EVGA NU Audio cards are an example of that approach.

 

[mansr]

But what if PCIe is worse than USB, and having a USB link in between actually acts to clean it up? When you start believing things like this, where do you stop?

 

[sumpao]

If you guy believe bit are bit so USB to DDC and DDC to dac by i2s the bit should be the same right?

 

[Veri]

so USB to DDC and DDC to dac by i2s the bit should be the same right?

That's what we're saying yeah.