Thanks guys! You answered my question. Interesting and most helpful.
HDMI cable for I2S
I’ve got an old Oppo DV-970HD I’m using as a transport into my Musician Pegasus R2R DAC in my headphone rig. The Oppo has an HDMI out (that does output 2-channel PCM) and the Pegasus has an HDMI I2S input, so I was wondering if any HDMI Cable will work for this? I recall someone saying you need to check with the DAC manufacturer to see which pins are live, but just wanted to check here to see if I’m missing something or if this can even work. I’m thinking of getting a 0.5m DH Labs Silversonic HDMI 2.1, so would this cable possibly work for this? It’s marketed as a video cable so not sure if that means anything or if HDMI is the same for audio or video. Thanks for any help/insights.
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The crux of the matter when connecting different brands via HDMI I2S is pinout matching since there is currently no standard. Assuming the output is in fact I2S since they HDMI terminals visually look similar. I'f I'm not mistaken the Pegasus has the ability to accommodate several options to match the I2S pinout of other equipment. Check with Musician or the web as I've seen a diagram posted.
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@auxinput is correct and the HDMI input on your DAC has nothing to do with the HDMI output on your Oppo. They are two different animals. They are the same physically but the type of signals they require are completely different. Do not plug one into the other. If you want to use the HDMI input on your DAC you need the Oppo I2s card, no ifs or buts or whatevers. The HDMI output on your Oppo transmits Video and Sound for watching movies and as Auxinput correctly said if you decode the sound from this HDMI cable it won't be better than COAX. |
yes, there is a difference (that is if you are actually using a real i2s output board on the Oppo). I2S is the native PCM bit information for each channel. There are two separate channels that require two different connection. S/PDIF will take the 2 channels of i2s data and encode it all into a single bitstream. It is clocked the same, but transmitted over a single wire. At the receiving end, the device has to decode the bitstream and separate the data out into two i2s channels again. This raw i2s data is what is sent to the DAC chip.
If you use the standard HDMI video output of the Oppo, you need to connect this to an A/V pre/pro or receiver. The Oppo will take the S/PDIF data and break it into HDMI data packets (essentiall de-clocking the S/PDIF signal because the data packets are merged into the HDMI audio/video data using HDMI clock signals). This is what is called PCM-over-HDMI. The pre/pro or receiver will have to extract the audio data packets and re-clock that into the proper PCM sampling rate before sending it to the DAC. If you compare PCM-over-HDMI with a normal S/PDIF coax connection, the S/PDIF coax will generally be superior and have much more dynamic range and better sound. |
I2s is another transmission method, an alternative to USB, SPDIF(AES & RCA COAX) or even TOSLINK. Currently I2s is usually transmitted using HDMI or RJ45 cables. PCM is a method of storing music and usually uses WAV or FLAC formats. DSD is the King of the Hill and is usually stored in DFF files, unless DSD is on a SACD. If your DAC cannot play DSD it will be converted to DOP, not quite as good but acceptable. There are also Apple formats, MQA and MP3. I don't know of any format or currently used frequency that I2s cannot transmit. |
I2s will give superior SQ to any other connection and using the Oppo Card above you'll get Native DSD into your DAC. You could also get Native DSD over USB but the Oppo doesn't output USB. I2S Card Upgrade - $220This is add on card which extracts the I2S signal from OPPO's internal digital audio data and transfers via HDMI to the I2S input of DAC's such as the PS Audio DAC. |
The HDMI output is PCM, same as what comes out of the SPDIF output. So I’m thinking there’s not much value in using an HDMI cable or if the I2S input on the Pegasus would even recognize it. Or, is the I2S PCM output the same as SPDIF and the difference is in the cable? |
Well, ‘no’ may not be the best answer to the question from soix. I2S most definitely will use any standard HDMI cable to transport the clock and data signals between two compatible I2S interfaces. I use I2S all the time with standard HDMI cables. The question should be, is the output from the OPPO truly I2S or standard HDMI? The specs I read indicate a standard HDMI audio/video out from the OPPO, no mention is made of I2S. So, while you certainly can use HDMI cables for I2S to I2S, you won’t get any signal from a standard HDMI out to I2S. Hope this helps.
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