Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems HD621 or G68 5.1 downmix to 2.0

Hi - please see equipment in my sig...I recently acquired G68SL and HD621 but have for now only 2 speakers.

The only way I seem to be able to get movie dialog at acceptable volume is by configuring the HD621 type to 2 channel PCM.

I had been hoping I could send 5.1 channels from HD621 over MHR to the G68SL and have the G68 downmix to 2.0, but with the HD621 configured for 5.1 there is no DSP selection on the G68SL that gives clear dialog, so I assume I am missing the center channel info altogether. This was with DTS-MA on Blu-Ray, but I think its probably the same on DVD.

I have
- G68 configured with only 2 large (L/R) speakers
- Oppo set for 5.1 (vs 7.1) output (but not sure that this affects HDMI output at all or only the analog outputs)
- Oppo decoding to LPCM
- HD621 sending high sample rate (88/96 kHz) over MHR (3 blue cables)

Is there any another way that would allow the 5.1 to get to the G68SL ? Am I right to assume the G68SL would be better at downmixing?

many thanks for any tips
Sanjay

Hi Sanjay,

Have you tried outputting non-decoded from the Oppo?
Your info above suggests you are wanting the G68 to downmix BUT giving it LPCM to process in order to achieve that.

I wonder if giving it native DD/DTS will make any difference. Maybe decoding and downmixing are best handled together?

Are you playing DVD or Bluray source ? This may impact the above.

Just ideas but worth testing in your config.

Cheers

He says he is playing DTS MA on BD, so the Oppo has to be set to output LPCM.

I think you need to check your connections between the HD621 and G68. I don't have this setup but seem to remember there being isues about how the non-MMHR outputs of the HD621 were labelled i.e. which outputs go where for your 3 blue cables.

Thanks Asa. I am using MD1 as follows which I believe to be correct based on other posts here.

HD621 > G68
1/2 > D1=L/R,
3/4 > D3=C/LFE,
5/6 > D5=SURR

Sanjay

ncpl, I'll try non-decoded from Oppo to G68 using DVD with HD621 set for multichannel and see if that's different - this may be instructive, but as Asa says it wouldn't work for Bluray DTA-MA or Dolby TruHD

Sanjay

Anyone else tried this? How well does G68 downmix 5.1 LPCM to 2.0 and are there any config tricks for this?

Certainly with properly authored MLP as used with DVD-A and the basis of Dolby TrueHD, the 2 channel mix is stored and the multi channel is derived from this by applying delta changes for surround info. This is a design feature in MLP that allows a track to be played even on simple 2 channel devices.

If it is the norm that discs do indeed follow this method, then having the basic 2 channel mix extracted by the source must be the most pure method. Purporting a multi channel mix would involve the source taking the 2 channel mix, adding the multi channel delta info, sending the multi channel mix to processor which then needs to fold the multi channel mix back in to the original 2 channel mix.

Certainly with MLP based discs, outputting as 2 channel would to ke seem the best method and also the simplest.

I have at least one disc (Harnoncourt Matthew Passion) where DVDA-Explore extracts a stereo mix which as a weird channel imbalance. Anyone else found that?

Ian - thanks & most interesting. What is working now is Oppo outputs multichannel LPCM over HDMI to HD621 which is typed for 2 channels that it sends it over MHR to G68SL.

I can set Oppo for 2.0 but I have a feeling this affects the analog Oppo outs which I am not using and not the HDMI output - does anyone know more about this?

At least the G68SL apodizes my Squeezebox (SPDIF input).

By the way I also notice that DVD-A through the Oppo BDP-93 HDMI/HD621 does not reach the audio heights of my previous setup which was G91 stereo analog output direct to the G57. Although I also added a PS Audio Quintet power center, so other things changed too and I no longer have the G91.

This might seem a daft question, but presumably you have checked that you've set the G68 to only have two speakers in the speaker choice menu in the wizard accessed from the front panel (at least thats what I use - I've never braved Mconfig)? If you have, then no matter what it is fed from the HD621 it should surely mix everything to the only two speakers it thinks it has ? If you've done it right, the only DSP modes you can get will be those like direct, mono, Trifield and none of the multi channel ones.

I wonder why the processors 568, G61, G68, 861 can't do a proper downmix when the HD621 is set to 6ch?

Are we certain that we get True-HD/DTS-MA when the HD621 is set to 2ch? I'm afraid that we get the core-track, which is a lossy format. (This is what you get out of the SPDIF)

I have been playing with this kind of 2 channel config for the past two years and despite what all the manuals say and with everything I read about setting the player to LPCM, I get a far better sound out of DVD and Bluray by sending Bitstream to my HD621/G61RSL. When I send LPCM I get a standard stereo sound but when I send Bitsream I get a true Movie sound, meaning super Dynamics and clear voices. It's like adding a sub and is no contest sonically. There is no difference in configuring the HD621 from 6 ch to 2 ch when sending Bitstream that I have heard. I suspect I may be getting a DTS signal that the G61 is mixing to 2 channel. It sounds so much better that for the first six months while my source was set to LPCM I had no real base or significant dynamics. I even bought a sub because of it. Then I changed my player to Bitstream and didn't need my sub any more. Dialog is also great.
I have searched the forums for what the HD621 'Types' mean, thinking that maybe I need to choose a type and then will be able hear the High Def Codecs like True HD but still have not found anything. I don't believe I am getting them set up with 2 channel.

This LPCM topic makes sense on paper but there is no way I will watch a movie with my source set to LPCM. It does not sound as good.

I would love some feedback.