I2S RJ45 cable type

[otec]

Hi

I have LKS audio mh-da003 DAC and decided to connect a second PC to it. I bought XMOS U8 device from aliexpress that supports (DSD64, DSD128, DSD256 (2.822, 3.072, 5.644, 6.144, 11.2896 and 12.288MHz)).

I'm connecting XMOS U8 to DAC via I2S ethernet socket using a standard off the shelf Cat5 network cable. When I play music from foobar in DSD256 I hear a lot of noise.


A question, can I use unmodified Cat 5e network cable for this connection ? Or do I need to re-wire it according to I2S spec of XMOS/DAC ?

ps.

XMOS that I have is
Upgraded version XMOS U8 + TCXO 0.1PPM USB Digital Interface 32Bit / 384K Support DSD PCM I2S AES EBU Coaxial Optical Output -in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group

Sorry for a newbie question.

 

[DF96]

I'm no expert on these things, but I think you will find that I2S is not Ethernet and so you should not expect an Ethernet cable to work. I2S is for local connections between chips on the same PCB; Ethernet (in its various forms) is for connecting different equipment which may be 10's or 100's of metres apart.

 

[Eldam]

If DF96 is not an expert, few can help you....

The fragile I2S signal is not designed to be transported on long distance (more than few cm into a device) as writted.

Some thoughts :

- cheap ALLI is not a guaranty of good designs, better to look at this : http://www.twistedpearaudio.com/digital/teleporter.aspx ; https://www.minidsp.com/products/network-audio

But it will be always with a waste of the signal... if transported in I2S protocol on long distance (If I understound the general idea of the concept)

I2S signal should be transported with the same impedance between source and destination as it's a fragile signal. Most of the time this is the 50 ohms of the pcb (DF96 will correct me if I'm wrong with all these inputs) impedance with dac pcbs. Cat5e is 100 ohms impedance if I remember, you can always try it on few cm (less than 10 cm), but better result will be comming from 50 ohms interconnexion. Sometimes the rest of the dac or whole hifi can not be good enough in this context for you to hear a difference !

But if noise, you simply buy a crap device.

But being not an expert into the clan of "non-experts", I don't know if it that can helps !

 

[otec]

Thanks! That's what I thought. I studied pin layout of DAC and XMOS interface and they are a bit different. On one pin DAC expects DSD/PCM signal switch, which XMOS doesn't provide.

Looks like I will have to use other type of cabling

Sent from my Nexus 6P using Tapatalk

 

[DF96]

I think for I2S short distance is the key, not cable type. I seem to recall that in another thread someone said that I2S does not have a defined impedance, as it is only used over such short distances that the cable does not need to be considered as a transmission line.

 

[canvas]

Most I2S output I 've seen is driven by buffer/transmitter, like AM26C31 or HDMI buffer. Without them, long transmission is a problem. You can try a really short CAT6A/CAT7 cable. No more than 30CM, perhaps 20CM.

 

[otec]

Got it.

First thing first, I would need to re-wire RJ45 on DAC and XMOS U8 sides to match the pin layout. I will let you guys know how it went.

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