I2S cabling
Jun 16, 2006 at 6:49 PM Thread Starter Post #1 of 10

studeb

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I want to run an I2S cable from my CD player to my DAC. Is there a preferred/recommended cable for this. One end will go straight on the chip (SAA7210) the other will be terminated in a 5pin mini DIN plug.

ta
 
Jun 17, 2006 at 12:59 AM Post #2 of 10

Nerull

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Garbz would be all over this.
biggrin.gif

But since he's not here (as of now) I'll say it.
He recommended I use coaxial cable with a seperate ground
for each data line. I2S probably would induce a lot of interference
if not properly shielded or grounded. It would also be a good idea
to keep this connection as short as possible (I heard the signal can degrade rather quickly over longer cables.)

Good luck though!

~Tom
 
Jun 17, 2006 at 1:17 AM Post #3 of 10

Garbz

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You're biggest problem is radiating RF. Ideally you want to transport I2S out especially if it's more then just a few cm I'd pick several coaxial connections.

If size is a problem canare sells minicoax cable where there's 5 coax cores per cable, and you could terminate them to the small N-type connectors.

Mind you feel free to use any method you want just remember that there's a chance with a longer cable at thoes frequencies (6.5mhz and up for BClk and MClk) you may get garbage out the other side if they aren't properly shielded. Also if MClk is 24Mhz and it's not shielded you'll loose CB radio channel 4 in Australia
very_evil_smiley.gif
 
Jun 17, 2006 at 3:34 AM Post #4 of 10

studeb

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Quote:

Originally Posted by Garbz
You're biggest problem is radiating RF. Ideally you want to transport I2S out especially if it's more then just a few cm I'd pick several coaxial connections.

If size is a problem canare sells minicoax cable where there's 5 coax cores per cable, and you could terminate them to the small N-type connectors.

Mind you feel free to use any method you want just remember that there's a chance with a longer cable at thoes frequencies (6.5mhz and up for BClk and MClk) you may get garbage out the other side if they aren't properly shielded. Also if MClk is 24Mhz and it's not shielded you'll loose CB radio channel 4 in Australia
very_evil_smiley.gif



Thanks for the advice. My wife is talking about moving to Melbourne, so must keep that in mind.
Hmm RF huh, that must be the new high pitch my CD player produces, or induces. i picked up some Cat5 from work, but when i got home i realised that it is not shielded. It works, but i will look for some shielded. i am not using MClk, just CLAB WSAB and DAAB and shield is ground. The DAC is a Perpetual Tech P-3A which has a mini 5 pin DIN jack, and i think i can keep length to 10 cm, less if i go straight up through the chassis.Would running MClk improve things noticably? If so then i how do i run it to the chip and remove the Xtal?
If anyone cares the player is a Magnavox CDB 650.
 
Jun 17, 2006 at 11:40 AM Post #5 of 10

Garbz

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! The DAC has an I2S in as factory standard? Id take care there's no clear standard to how this is done. I'd be interested what master clock the DAC runs off if not the one the cdplayer supplies.

And in any event I haven't heard of thoes lines. What do they stand for? We may be talking about entirely different things here.
 
Jun 17, 2006 at 3:29 PM Post #7 of 10

studeb

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Quote:

Originally Posted by Garbz
! The DAC has an I2S in as factory standard? Id take care there's no clear standard to how this is done. I'd be interested what master clock the DAC runs off if not the one the cdplayer supplies.

And in any event I haven't heard of thoes lines. What do they stand for? We may be talking about entirely different things here.



The lines off the chip i am using are word select (WSAB), data (DAAB) and clock (CLAB). They go to frame sync, data and ser clock on the DAC.
i thought I2S was a standard and wired them up this way. i get lock and it plays. i can send you pics of the board if you want. i was going to start a mod thread, just replacing caps and diodes like Edwood's DAC 2 thread.

The input is factory standard, i think the company founder was from Audio Alchemy, and has continued to use their I2S implementation. i believe there is a MClk out from the DAC, but haven't used that. Maybe i am wrong but i thought you did not need the MClk from the DAC to use I2S.
 
Jun 17, 2006 at 4:47 PM Post #8 of 10

00940

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If there's a MCLK out of the DAC (which implies a clock inside the DAC), wouldn't be just as easy to use feed it back to the transport and keep the spdif link ? It will actually be better than an I2S link from the transport.
 
Jun 17, 2006 at 4:58 PM Post #9 of 10

flecom

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Quote:

Originally Posted by Garbz
You're biggest problem is radiating RF. Ideally you want to transport I2S out especially if it's more then just a few cm I'd pick several coaxial connections.

If size is a problem canare sells minicoax cable where there's 5 coax cores per cable, and you could terminate them to the small N-type connectors.

Mind you feel free to use any method you want just remember that there's a chance with a longer cable at thoes frequencies (6.5mhz and up for BClk and MClk) you may get garbage out the other side if they aren't properly shielded. Also if MClk is 24Mhz and it's not shielded you'll loose CB radio channel 4 in Australia
very_evil_smiley.gif



N connectors are not small lol! three of them would be pretty huge too... maybe you should use DIN connectors? mmm, compression fittings are your friend! maybe you are thinking of TNC connectors? or BNC connectors?

how many ohms are those lines tho, would you want to use 75 ohm or 50 ohm coax?

if its 75 its easier to find 75 ohm BNC connectors (most TNC/N connectors are going to be 50ohm) and they are rated for v/uhf so 24mhz should be no issue
 
Jun 18, 2006 at 1:30 AM Post #10 of 10

Garbz

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Lol 75ohm bnc connectors are hens teeth around here which is why I recomended something else.

Anyway now I know which DAC you mean. I previously owned one curtosy of a friend leaving town for 3 months.

I2S is a method for serial data transmission. That's it. It's like LSB serial, or MSB serial. The fact is that the last DAC I used called the lines something else.

You could try running Shielded Twisted Pair. Grounding the shield and all but 3 signal wires. This would also have the bandwidth for this application, and provide shielding and hopefully data integrity.
 

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