Reply To: SupTronic WX6000 Multifunction Expansion Shield 7.1 Channel Surround Audio Syste

22. Mai 2019 at 14:58 #45474

Dear all,
This is about the add-on sound module for the RPi. It is sold as the X6000 by SupTronics OR the ST6000 sold by Audiophonics in France. The boards are identical and even have the same photos of the inputs and outputs especially the 4 x 3.5mm analogue outputs.

If one shops around, the X6000 can be purchased for AU $64 from dx.com. For the purposes of the discussion, when I refer to the X6000 or ST6000, I shall for simplicity refer to the X6000.

For your information, the board is sold as an add-on for the RPi. Apart from the mechanical footprint/form, the X6000 does not need the RPi. There is nothing from the RPi’s GPIO that interacts electronically with the X6000.

Thus you can connect anything to the X6000’s hdmi input. In my situation, I have connected a blu-ray player’s hdmi output to the X6000’s hdmi input. Of course I connected a 5V(dc) 5A supply which is located at the front – either via two pins or a 4.75mm outer-diameter barrel supply or soldering two wires to a 5.5mm outer-diameter socket to the 5.5mm outer-diameter plug from the power supply.

You may ask: how does it apply to the RPi? My answer is that once you know how the X6000 handles signals, you will know what signals from the RPi’s hdmi output are needed.

This report is based on my experiments with my blu-ray player. The great bulk of my analysis is found at https://yabb.jriver.com/interact/index. … c=115052.0 under the name „Anthony The Koala“, also at https://www.diyaudio.com/forums/digital … video.html under the name „Anthony The Koala“, 5th November 2018.

Here is a summary of the facts from my experiments:
* The X6000’s 3.5mm analogue outputs are decoded LPCM signals. I will return to this.
* The X6000’s optical SPDIF will pass to a maximum of 5.1 channels .lossy versions of Dolby and DTS.
* The X6000’s hdmi output will pass all variants of 1/2/5.1/7.1 lossless (1/2/5.1.7.1) variants of Dolby-HD and DTS-MA and LPCM and lossy variants (1/2/5.1) Dolby and DTS variants. To decode these signals you will need an HDMI processor or a/v receiver with hdmi connections that decodes these signals.

Recall that the X6000’s 3.5mm analogue outputs are decoded LPCM signals. What does this mean?
* The X6000 does not decode lossless Dolby-HD and DTS-MA signals. NOR does the X6000 decode the lossy versions of Dolby and DTS.
* the hdmi source signals must be LPCM. If the source signals were bitstreamed lossy or lossless variants of Dolby and DTS signals, YOU WILL HEAR NOISE AND BUZZING on the 3.5mm analogue outputs.

What is bitstreamed? When the blu-ray player’s hdmi audio output to ‚bitstream‘, your player will send the lossy and lossless versions of Dolby and DTS as well as LPCM. Yes there are some rare occasions where the audio on a blu-ray is LPCM.

What happens when I set my blu-ray player’s hdmi audio output to ‚LPCM‘, it converts the lossy and lossess Dolby and DTS signals to LPCM. IT IS WHAT IS NEEDED IN ORDER FOR THE X6000 TO DECODE.

Do all blu-ray players allow conversion of variants of Dolby and DTS signals to multichannel LPCM? NO! Some players such as LG’s BP125, BP240, BP420 and BP450 will downmix all signals to two channel PCM. Other players such as Panasonic’s DMP-BT370 and Laser’s BD3000 have the facility to convert any multi-channel audio signal to multi-channel LPCM.
Lesson: CHECK YOUR PLAYER’s MANUAL

Now:
* we know that to decode the the audio output at the 3.5mm analogue outputs, the X6000’s hdmi input audio signal must be LPCM. Hence the source signal from the blu-ray player, media player and RPi must have its hdmi audio output set to LPCM.
* we know that the X6000’s hdmi output will pass any signal that is at the hdmi input. That is any lossy and lossless variants of Dolby and DTS even Atmos and X respectively. NOTE: that only occurs if the source signals from a blu-ray player, media player and RPi is bitstreamed. BUT you won’t hear audio at the 3.5mm analogue output.
* we know that the X6000’s optical/spdif will only pass lossy variants of Dolby and DTS to a maximum of 5.1 channels.

Now that we know the hdmi’s audio signal input and outputs are for the X6000 will decode ONLY LPCM for the 3.5mm analogue outputs and pass lossy signals through the SPDIF (optical) while the hdmi output will pass lossy and lossless signals.

How does that apply for one’s RPi? Since the X6000 only decodes LPCM to the 3.5mm analogue outputs, it follows that the RPi’s hdmi output must output its audio signal to the X6000’s hdmi input in LPCM! This is because LPCM is the only kind of audio signal that is decoded by the X6000!

What does it tell me about the X6000/ST6000?` It tells you that they both come under the same family as other HDMI LPCM audio extractors such as Cypress’s CLUX-11SA and A3080 sold by Altronics. The list is not exhaustive, with a lot of the units looking the same but with different ‚brands‘. They all do the same thing at the analogue 3.5mm outputs – they only decode LPCM.

But my RPi may handle all the lossy and lossless variants of Dolby and DTS! That may be true especially where there are software packages that decode blu-ray, DVD and other multimedia files Maybe the software does not explicitly inform the user that the lossy and lossless signals are converted to LPCM, the audio signal at the RPi’s hdmi output must be in LPCM otherwise the audio at the X6000/ST6000’s 3.5 analogue outputs will sound noisy and buzzy.

SUMMARY
* The X6000/ST6000 is a form of hdmi lpcm audio extractor. Though it has the same mechanical form/footprint as the RPi, any kind of player with an hdmi output can be connected to the X6000/ST6000.
* The X6000/ST6000 only decodes LPCM at the 3.5mm analogue outputs. Regardless of blu-ray player, media player or RPi with appropriate software, the source hdmi signals must be in LPCM.
* Once you understand the signal systems of the X6000/ST6000, the performance exceeds those other hdmi lpcm audio extractor. Furthermore if you shop around, the X6000/ST6000 can be lower in price than other hdmi LPCM audio extractors.
* The X6000/ST6000 will pass at the hdmi output any lossless and lossy signals to a maximum of 7.1 channels or more such as Atmos and X while the SPDIF will only pass lossy signals
* Of course if you are running the X6000/ST6000, you will still need to connect it to a 5V(dc) 5A supply which can be connected to either two pins or a 4.75mm barrel socket or wiring in a 5.5mm barrel socket.

I hope that clarifies the issue of using the X6000/ST6000. I am impressed with the sound quality.