I2S over HDMI vs. Cat-5 and "Native Mode"

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davidR

  • Jr. Member
  • Posts: 18
I2S over HDMI vs. Cat-5 and "Native Mode"
« on: 12 May 2009, 09:07 pm »
Hey Steve, I post over on Computer Audiophile. I was doing some reading on the PS Audio PerfectWave DAC today. I was surprised to find out it provides I2S inputs, but interested in the fact they are doing it over HDMI connection. This is directly from the PS Audio website:

"PS Audio has searched for a long time for the perfect cable to transfer I2S data. Some manufacturers use CAT-5 which is the cable your computer connects up to the internet. We took one look at this method and rejected it out of hand. The best solution we found was HDMI (High Definition Multi-media Interface). An HDMI cable is the best multi-conductor digital cable made today and it was the obvious choice for the PWT."

What is your take on this approach? Is there even a real advantage to HDMI vs. Cat-5 or are they simply turned off by the idea of an "internet computer cable" for fear of turning away audiophiles? They also talk about using the I2S input as "Native Mode" which bypasses the SRC. The other options include switching between 44, 88, 96, 176, and 192khz SRC with all options being inferior to running in Native Mode, which is only available using I2S. I interpreted their statement as due to the decreased amount jitter and superior data transport via I2S the SRC isn't necessary; but I'm not clear on how this exactly works. Can you further elaborate? Maybe I'm making this more complicated in my head than it really is. I really appreciate your time and thoughts.  -David

audioengr

Re: I2S over HDMI vs. Cat-5 and "Native Mode"
« Reply #1 on: 13 May 2009, 06:41 pm »
Hey Steve, I post over on Computer Audiophile. I was doing some reading on the PS Audio PerfectWave DAC today. I was surprised to find out it provides I2S inputs, but interested in the fact they are doing it over HDMI connection. This is directly from the PS Audio website:

"PS Audio has searched for a long time for the perfect cable to transfer I2S data. Some manufacturers use CAT-5 which is the cable your computer connects up to the internet. We took one look at this method and rejected it out of hand. The best solution we found was HDMI (High Definition Multi-media Interface). An HDMI cable is the best multi-conductor digital cable made today and it was the obvious choice for the PWT."

What is your take on this approach? Is there even a real advantage to HDMI vs. Cat-5 or are they simply turned off by the idea of an "internet computer cable" for fear of turning away audiophiles? They also talk about using the I2S input as "Native Mode" which bypasses the SRC. The other options include switching between 44, 88, 96, 176, and 192khz SRC with all options being inferior to running in Native Mode, which is only available using I2S. I interpreted their statement as due to the decreased amount jitter and superior data transport via I2S the SRC isn't necessary; but I'm not clear on how this exactly works. Can you further elaborate? Maybe I'm making this more complicated in my head than it really is. I really appreciate your time and thoughts.  -David

First of all, we dont use "Cat-5" cabling.  The cables we sell and provide are much higher quality, such as the Revelation Cryo-Silver I2S cable.  I dont know if there is an equivalent HDMI cable to compete with this.  The Revelation cable is also a "nice" impedance to work with - 120 ohms.

Usually I2S is a direct connection (with buffering) to the D/A chip.  The reason for doing it is not only lower jitter, but a method to bypass SRC.

The PSAudio interface is differential (signal and inverted signal), meaning that the receiver will have some amount of common-mode noise rejection.  The problem with this is the limited number and quality of buffers that are available.  Most of them are too slow compared to the single-ended buffers (signal and ground-return), and therefore introduce more jitter than the single-ended buffers.

This is why I use single-ended buffers.  They are faster and add less jitter.  It's not about the cable or connector, it's about the electrical interface.

Steve N.
« Last Edit: 14 May 2009, 01:06 am by audioengr »

GreenLeo

  • Jr. Member
  • Posts: 6
Re: I2S over HDMI vs. Cat-5 and "Native Mode"
« Reply #2 on: 13 May 2009, 11:38 pm »
Can you explain what is SRC?

audioengr

Re: I2S over HDMI vs. Cat-5 and "Native Mode"
« Reply #3 on: 14 May 2009, 01:05 am »
Can you explain what is SRC?

Sample-Rate-Conversion - Many DACs have hardware upsamplers to reduce jitter.  Many do 44.1 to 96 or 192.

Steve N.

HiroPro

  • Jr. Member
  • Posts: 20
Re: I2S over HDMI vs. Cat-5 and "Native Mode"
« Reply #4 on: 25 Mar 2013, 08:23 pm »
Hey Steve, I post over on Computer Audiophile. I was doing some reading on the PS Audio PerfectWave DAC today. I was surprised to find out it provides I2S inputs, but interested in the fact they are doing it over HDMI connection. This is directly from the PS Audio website:

"PS Audio has searched for a long time for the perfect cable to transfer I2S data. Some manufacturers use CAT-5 which is the cable your computer connects up to the internet. We took one look at this method and rejected it out of hand. The best solution we found was HDMI (High Definition Multi-media Interface). An HDMI cable is the best multi-conductor digital cable made today and it was the obvious choice for the PWT."

What is your take on this approach? Is there even a real advantage to HDMI vs. Cat-5 or are they simply turned off by the idea of an "internet computer cable" for fear of turning away audiophiles? They also talk about using the I2S input as "Native Mode" which bypasses the SRC. The other options include switching between 44, 88, 96, 176, and 192khz SRC with all options being inferior to running in Native Mode, which is only available using I2S. I interpreted their statement as due to the decreased amount jitter and superior data transport via I2S the SRC isn't necessary; but I'm not clear on how this exactly works. Can you further elaborate? Maybe I'm making this more complicated in my head than it really is. I really appreciate your time and thoughts.  -David

They did it so they can sell you an expensive HDMI cable. That same outfit has $800 power cords for god's sake. I'm not saying their DAC isn't any good or anything but man... if the outfit sells $800 power cords I question their ethics.