The only company that uses I2S over HDMI is PS Audio. |
Most I2S is not over HDMI (except as Kr4 pointed out, for PS Audio), but there are several different I2S interfaces. The difference between the I2S and the common s/pdif is that the I2S includes the word clock communication, allowing a DAC to sync with a transport, minimizing jitter.
Coax (s/pdif) is superior to toslink (optical) in almost all applications (due to lower jitter amongst other things). AT&T is superior to s/pdif in most applications...
USB... can be a good interface, but many times, not very well executed. HDMI, potentially a very good interface, but contains all kinds of copy right protection which can screw up the sound... |
I2S is also used in the Wyred4sound dac2. |
That's 2. Not as many as the original I2S and not standard HDMI either so that's a consideration. |
Given that the system does not have significant ground-loop noise, the coax interface will outperform the Toslink, If you use a decent coax cable that is. The Optical conversions add jitter. If the system has a lot of ground-loop noise, the Toslink will be better simply because it breaks the ground loop.
I2S is the native interface to most D/A chips. Because there is no need to encode the clock and data into a single signal, this makes it superior technically to S/PDIF coax. Termination and handling of the transmission-lines of I2S is non-trivial however and many of the early implementations were not very good. I2S consists of 4 signal lines: MCLK, SDATA, L/RCLK and SCLK (aka BITCLK). The HDMI connector used with the differential version of I2S was chosen by PSAudio and adopted by Wyred 4 Sound and Empirical Audio, who also uses RJ-45. I2S has been used in single ended version with DIN and RJ-45 connectors for about 10 years. The earliest was Audio Alchemy. Differential version has 8 signal lines and ground. Single ended has 4 signal lines and 4 return lines (grounds).
Steve N.
Empirical Audio |
I2S is also available on North Star as RJ-45, which I am using.
It certainly is the best connection. |
I wish to thank all for their response. Are there no USB/SPDIF converters that output I2S to any of the aforementioned DACS? |
Dunno but it is doable. I wrote a pair of articles many years back (1995-7) about how to do this. They appeared in Audio Amateur which has morphed into AudioXpress. The articles were called "Get on the Bus" parts 1 and 2. While the specific devices referred to are a bit dated, the general principles are the same. |
Mesch- the Empirical Audio Off-Ramp 5 outputs both differential HDMI I2S and single-ended RJ-45 I2S. it works with W4S DAC2, PS Audio PWD, Northstar, Stello, Empirical Audio, Perpetual Technologies, Buffalo and others.
Steve N.
Empirical Audio |
Steve, please consider including a coax input on the Offramp 5 so that I can buy one to put between my Squeezebox Touch and my W4S DAC2. I would really like to try feeding the DAC2 via I2S. |
Cymbop - It has Coax. The OR5 has BNC coax (with RCA adapter), AES/EBU, RJ-45 I2S and HDMI differential I2S. All active at once.
The OR5 USB interface does not currently support Linux without a special driver. OR6 will be XMOS, so it will work. OR5 is upgradable.
Steve N.
Empirical Audio |
did some extensive testing of the I2S connection when i got my PS Audio PWT/PWD back in 2009. all three listeners easily preferred the I2S connection....and i stress the "easily" part as it was obvious to us. we went on to compare the set-up to higher priced gear and the I2S connection held its own...besting transport/dac combo's that cost considerably more. the same was *not* true when we used rca or xlr with the PWT/PWD.
i walked away thinking I2S was the difference maker when properly implemented/executed. i still believe that today.
just my 2 cents though. your mileage could vary. |
Steve, the only _input_ on the OR5 seems to be USB. And there's no USB Out from a Squeezebox Touch. |
Again, I wish to thank all for their comments. When I upgrade I wish to take advantage of the I2S interface.
Steve, I must add that I very much appreciate the Empirical Audio Web page information. |
Steve, Cymbob is asking for coax INPUT, not output. |
Cymbop - Actually you can stream USB output from SB Touch, but it requires a USB converter with Linux driver compatibility. The HiFace2 will work.
If you wanted to reduce jitter from S/PDIF coax or Toslink, this can be done with a reclocker like the Synchro-Mesh. Unfortunately, there are none with I2S outputs .... yet.
Steve N.
Empirical Audio |
Quick update on this. Reassuringly I2s is really catching on. These manufacturers (at least) offer I2S inputs or converters:
- Pink Faun
- Sonore
- Wyred4Sound
- PS Audio
- K&K Audio
- Audiobyte / Rockna
- Wadia
- Love Harmony
- MSB Technology
- Empirical Audio
- Northstar Design
- LKS Audio
- Ayon
- Stello
- Audio Alchemy
- Perpetual Audio
- Camolot
- Aquasound
- Audio-GD
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Way, way back I used I2S cables on Audio Alchemy gear.
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AES/EBU is the best short of IP audio.
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Interesting thread. I am currently connecting my Apple TV to my DAC (Cambridge Audio Azur 851 D) via toslink. I was advised that this was a better route than coax.
I'm thinking of replacing the Apple TV with a Bluesound Node 2. Based on the opinions on this thread, it seems coax is a better alternative if ground loop noise is not a factor. |
