I2S Cable length?


#1

Hi

Does anyone know what cable length is recommended for a I2S HDMI cable between transport and dac. I was thinking of 1.0mtr. Is this length OK or would a 0.5mtr make any difference?

Thanks.


#2

Search the forum threads. This has been discussed a lot.


#3

Sorta usually driven by how close they are on the shelves. If they’re close enough, and you don’t think you will ever want them further apart, get a half. I think one consensus is not to stack them just so you can use a shorter cable - the potential interference is likely worse than any difference between .5m and 1m.


#4

Here is one brief previous discussion which may be of help: clicky


#5

Ok, here’s what I found just recently:

  1. Started with stock, supplied in the box PS Audio cable. Good, clear, neutral sound
  2. Moved DMP 20 ft away using a cheap hdmi BlueJeans/Belden. Sounded cloudy, dull.
  3. Moved the DMP closer and used a 9ft PS Audio AC12 (no longer available). Indisputably the best sound.

#6

I would be concerned with that 9 ft. length. it is funny that you prefer the AC-12 to the stock cable they supply with the DMP. Both Arnie and Paul prefer the new cable to the AC-12.


#7

I confess I don’t like the new supplied cable. No cable has displaced the HDMI AC-12 in my system.


#8

funny? It’s a laugh riot! All seriousness aside, I didn’t say I’m right. I just stated my experiences and taste.


#9

Yes that is true. Everyone’s systems and tastes are different. Just look at the reactions to the various DMP software releases.


#10

It’s been stated in the past that the I2S cable should be a maximum of 3M, so it’s not surprising a 20’ length didn’t sound good.


#11

I’ve found lots of opinions and even equivocations by those who we might expect to “know”, but no useful rule.
If asked, I would recommend one just use what came in the box and spend the rest of the money on music or a night out.


#12

There isn’t a rule as such.
I2S was developed as a chip to chip bus for PCB’s and as such was only good for a few inches. To transmit from box to box in a hifi situation the source component has a line driver stage to allow this. The distance that this will cover depends on the line stage design.

They should all be good for several meters though.

If you want more info, check out the i2s interface design PS Audio published on the web for anyone to use commercially and the TI line driver chip it used. The TI data sheet will probably give more on what that particular item is capable of doing. It was a smart move by PSA offering a HDMI pin out scheme and line driver schematic. Several manufacturers have adopted this pin out which makes them compatible with PSA equipment, Audio GD for one. The latter sell a line driver board with this HDMI socket pin out, which can be connected to a SBC like the Raspberry Pi. This can then be plugged into a Stellar GCD etc. I will get around to playing with one of these soon I hope.
The i2S output on SBC’s is not the best, Allo make the “kali” which is an i2S re-clocker that sits between the SBC and the line driver for better i2S output.
Sorry for the additional waffle, some folks might be interested in this aspect, and unaware of the possibilities.

My intention is to build a music streamer/server based on a SBC. This will be hard wired to my Routter/hub using Gigabit Ethernet cable and a NAS drive attached to the HUB for file storage. the SBC will be connected to the Stellar GCD using i2S. So not a USB or SPDIF item in the chain. My CD transport has i2S, but on a 5 pin mini XLR, I am considering converting this to HDMI socketry. Then it should be possible to adapt an HDMI switcher (with remote) to go between the CD and File sources to feed one or the other to the single i2S input on the Stellar GCD.


#13

Thanks!


#14

badbeef wrote: “Sorta usually driven by how close they are on the shelves… I think one consensus is not to stack them just so you can use a shorter cable - the potential interference is likely worse than any difference between .5m and 1m.”

Is there a discussion reference on the interference issue? Anything short of moving components to mitigate whatever effect there is? I’ve got a three shelf unit with an Oppo 203 sitting on a DirectStream dac on the middle shelf, with a 0.5m I2S-12 run between them (Oppomod HDMI/I2S card). Not much flexibility, as on top is an HDTV and on the bottom are a PS Audio PowerBase and a P15.


#15

Personally, I wouldn’t sweat it. But yes, there is a lot of discussion about it on the forums. Many seem to feel that having the units stacked on top of one another is a significant negative. I don’t personally have any experience with it one way or another… I have everything on separate shelves.


#16

Thanks. Right now I’m hunting around for an HDMI cable that’s on the warm side, if there is such a thing.


#17

That’s a darn good question. Preferences on HDMI cables from DMP to DSD has been discussed here somewhere quite a bit (forget where exactly). I found that it does make a difference what you use, but “warm” in the sense you would use it with ICs or speaker cables was not a descriptor that came to mind in trying the 4 or so different cables I’ve tried. Seemed to me to be more a matter of “more” or “less” information getting through.


#18

Yes, I think the closest to “warm” in HDMI cable differences I’ve encountered I would call more “full” than “thin” . . . . The PS Audio HDMI-AC-12 that I use is the most full and tonally pleasant I’ve used. I’ve tried a half a dozen cables but I haven’t tried the really expensive WireWord and am still not ready to spend that much on an HDMI cable, especially as I need a meter length.

I find that the SACD playback with this HDMI cable is excellent. Redbook lags just a hair behind. . .and I’ve actually decided to try an AES/EBU cable for Redbook playback from the DMP, I’m having the excellent (imo) ArcticCables build me one with higher grade Van De Hull wire. I have headphone cables from Roy at ArcticCables that I love, he does great and relatively inexpensive work. I’ve never tried AES/EBU so it will be a fun experiment.


#19

lonson, I suspect you’re correct about full vs thin. That is, HDMI cables, perhaps because of their dual purpose, are not being designed with the same tonal thought in mind as other types. Even PAD, which designed what everyone is saying is a warm and lush coax, describes its HDMI cable as neutral. You mistyped the PS Audio HDMI, as it’s an I2S-12, not AC-12, which is the power cord. I didn’t say, but the I2S-12 is what I’m using right now (actually the AC-12 too). But the Oppomod board is more on the neutral side, as was Ric Schultz’s power supply mod to my Oppo, so I’m poking around for a countereffect. It may be, as someone suggested in a related discussion on Audiogon, that the answer will be to change the fuses in my ATC SCM19A actives from the wonderful AM Ultimate beeswax to the HiFi Tuning Supreme CU, which is said to be the warm version. I’d prefer a solution that allows me to use I2S because it seems clearly superior to coax, at least short of spending a lot more for something like the aforementioned PAD Neptune.


#20

Actually when I bought my HDMI cable it was denoted an AC-12, and there was an AC-10, it was not called an IS-12. And it went away, which is too bad, really good cable. In a few weeks I’ll be trying out an AES/EBU. (I’m using the optical input on my DSD DAC for the DVR and the coaxial for my UDP-205). I think there’s a little superiority with the HDMI compared to coax with hi-res content, but with Redbook less so (the UDP-205 as a transport via coax, which I have a very good cable for, is nearly as good sound in my system, and coincidentally “warmer.”)