Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Using an HD621 with a 4K screen

Hi Marcus

Yes, you are right from my experience at least

The audio settings in the TV will also affect what audio signals get sent via ARC/eARC...

Yes TOSLINK is preferable to ARC, as is getting a Bluray player that has two HDMI outputs.

Microsoft in their wisdom, decided to remove a TOSLINK output on the new Xbox's, I imagine others will follow suite.

Best regards,
Frank

I have incorporated this device and split the signal from my Apple TV.

One feed to the projector and one to the HD621. You can set the output on the splitter to 5.1 on the feed to the HD621 which essentially tells the AppleTv to send 5.1 PCM audio out. The AppleTV then converts all audio output to 2 or 5.1 PCM audio output.

The input stream from the HD621 shows as PCM Movie6 96k with 5.1 content and PCM Movie2 96k with 2 channel content. I'm looking to eventually use an HDFury box to handle switching and audio extraction since I have more than one source without optical or digital output. For now, the ATV is the primary source (other than the UHD BD player) which has 2 HDMI outputs.

Nick

Hi

I solved a similar issue with a Vertex FuryHD. All of my sources plug into the vertex box, and then I run a HDMI cable into the HD621 for the audio (and onwards into a G68 processor) and another HDMI into the display.

Unfortunately my combination of sources (FireStick, Panasonic plasma, Bluray player, Humax PVR) and my desire to operate the "TV" as a TV (i.e. no surround sound for regular TV watching) means the Vertex can't auto detect the right source (it needs a certain type of signal on the input cable that one of the devices can't provide) and obviously doesn't know my intentions as it can't mind read, and so after some excellent support from Vertex themselves, I then got a 2nd hand Logitech Harmony remote.

Once I'd spent ages programming that (and still a few details to perfect) I now "just" need to select what activity I want e.g. Humax - TV, Firestick-TV, Firestick-Movie etc etc and these profiles boot up the relevant devices and then switch the vertex to the right source and audio output format (5.1 or 2 channel).

I've a few gremlins to sort out (firestick and multichannel needs another manual command as I've picked the wrong one in the script) but it can be used by the kids and wife so is fairly simple - turn on what you need to + choose what source and if it's TV or surround sound, and then you're good to go.

Of course, a modern screen and processor would "just work" but where's the hours of frustration and effort in that :-)

Not quite. With LPCM discrete channels, there is no encoding/decoding of various Dolby type formats. It’s pure SPDIF. The 861 does ZERO decoding. It reads stereo SPDIF pairs, and outputs the channels as defined. In this scenario, all the 861 DSP capability is used for upsampling/apodizing, room correction, et al…

The decoding MUST happen within the source device. In the case of ARC/eARC, it’s possible that the TV does decoding, but more likely it’s the source device (BR player, XBox, ATV, etc, …).

I noticed that the HD621 will upsample everything to 88.1/96Khz (or downsample to 44.1/48kHz) depending on the settings. We're using the 861v4 display of 96kHz as confirmation that it's receiving HD audio, but there's a chance it's being upsampled by the HD621. Is there a way to confirm that the 861v4 is actually getting uncompressed HD audio vs upsampled 48kHz compressed DD/DTS?

I'd be impressed if the HD621 was really a solution to get HD audio on my 861v4!

Thanks,
Chris

I recently connected an HDFury Vertex2 which shows the audio output format being sent to the HD621. It has varied depending on source content. The Amazon and Netflix streamed content has been 16 and 24 bit with both resolutions coming in with a 48k sample rate. I have yet to see anything greater from a multichannel audio stream. The audio output on my BD players is PCM converted from Dolby TrueHD or DTSMA and is often 24/96 out. The HD621 processes the 24/96 multichannel 5.1 (I have an 861v4) PCM audio wonderfully.

Nick

That’s great, thanks Nick!

As I only stream, I wonder if it’ll be worth it for me since I’m already getting 5.1@48kHz. Anyone seen higher bitrates while streaming on an AppleTV 4K? I’m expecting to see 96kHz if we’re really streaming HD audio?

Thanks,
Chris

Hi Chris ,

I need to make a correction ... I went and played through a few BD discs and realize that they are all 48kHz ... in fact, only some DVDA content I have is encoded with 24/96 content. So the 96Khz from the Bluray player is indeed upconverted through the HD621.

From the streaming realm, below is a screenshot of the AppleTV output from Disney+. This is from an episode of the Mandalorian. As you can see, even with the latest greatest streams the resolution is still 48Khz. Since the discs are not even using 96kHz resolution I doubt streaming will. Here is an interesting article about the new "high-quality" audio streams Netflix is using with....wait for it... up to a whopping 768kbs




Nick

Ah, interesting. So it seems that for streaming from an Apple TV 4K, it will output 5.1 LPCM at 48kHz which an optical connection should be able to handle. So no advantage using an HD621 over optical for streaming from an Apple TV 4K?

Optical is limited to 2ch 24/96, so HDMI is a must if you ask me for multichannel pcm.

About streaming, I think the highest they offer is dd+ with atmos, so nowhere near lossless high quality.

ATV4K does not have optical output.

Sorry, to clarify I’m using an Apple TV 4K with HDMI to an LG G1 TV, then optical from TV to 861v4. I’m assuming there is some degradation in quality when the TV converts from HDMI to optical, maybe the signal even gets compressed to fit 5.1 into optical?

ATV4K -> LPCM over HDMI -> LG G1 (passthru) -> optical -> 861v4

Thanks,
Chris