Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems 568 for stereo mixdown

Hello folks,

Its been a while since I've been here. I used to run an M system but currently I'm not. I decided to downsize from 5.1 to 2.1 and am currently running a Lyngdorf 2170 which works well and has really good room correction. However, I still watch the TV and films through this system via an optical cable into my Lyngdorf and I rely on the source or TV to do the stereo mixdown. This of course works, but I lose the LFE channel as the mixdown algorithm used in every (non-surround sound) device drops the LFE channel for fear of distorting the small little TV speakers. I do have a sub and I'm thinking of getting a more impressive one, but I want it to be used properly.

I had been wondering whether it was possible to buy a device which in and outputs digital audio and does a custom mixdown but then it occurred to me... I may actually already own a device which allows me to do custom mixdowns, in the shape of a 568.1 processor I never got round to selling (or 3 DSP33's but that's another story). It has an optical input I could take from the TV, and a digital co-ax out which would usually be to a pair of DSP speakers but which could go into the lyngdorf. it'll output at full volume with no volume control as the DSP's would do the volume control and I could configure the 568 for 2 full size speakers, each a metre away and with no sub so it should mix the LFE channel into the stereo output.

Would that work? That sounds to me like it would pass through a simple stereo signal and "pre-process" a Dolby Digital or DTS signal into a stereo signal but with LFE included. would I also be able to boost mixdown audio too as it's always quieter than plain old stereo?

I'm not quite ready to try it out yet as I'm in the middle of a few other things, so this is just thought engineering at the moment, but I'd be interested in what people think. is this a ridiculous idea?

Cheers

I have just inserted my old 565z3 between a Sky+HD receiver and an 818v3 to achieve a similar thing.

There are a number of operational issues such as Controller status, delay and synchronising inputs to be solved but it works well and sounds good.

I configured the 565 for a two-channel large digital set-up: Type 3, Layout M, No Surrounds.

Needs some extended listening and tweaking to decide if it is a keeper set-up.

You’ll have to set the output to HS=N or the output will be encoded.

interesting that someone else has done this too. in my use case, I don't think that there would ben a problem with controller status or sync'ing inputs as the device would be standalone. it would stay on a single input and not change anything in use. delay is an interesting one and I'd not considered that.


Hmm... I'd forgotten that.
Will it also encode the output of high res stereo input too, or just decoded surround sound? I mean I don't see it being a problem TBH, it would be between the TV and the DAC, my audio streamer feeds into my amp via USB anyway

I believe with HS set to N, the output is never encoded; I once ran a 568 through a 518 (as a volume control) to a DSP crossover, amps and ‘speakers and it all worked, albeit at 44.1 / 48kHz rather than 88.2 / 96kHz.

All the best,

Steve

Spent a few hours listening and tweaking...

Speakers are DSP7200.1 for left and right. The 565z3 feeds a digital co-axial input on the 818v3. Pre-sets are Digital for DD and Direct for PCM. Lip-sync is set to 0µs in both the Sky+HD box and the 818v3.

Caveat - my comparison use-cases are swapping from DD to PCM on the Sky+HD box rather than swapping to a PCM stream input direct to the 818v3.

The DD sound quality seemed better (actually really good) through the 565 with bass being deeper and punchier and musical soundtracks being more separated. I do however remember that when I put the 565 into my 5 channel system (after blowing up a G68) the bass was stronger.

The big problem is lip-sync. DD 5.1 and 2.0 soundtracks (via Sky+HD) are fine but PCM channels are way behind the picture. This suggests that whatever DSP (Trifield, etc.) processing is applied to PCM streams is also applied to the Direct pre-set for PCM streams. And it suggests that no processing is applied to the Digital pre-set for DD 5.1 streams and the Direct pre-set for DD 2.0 streams. I have not checked the speaker distances but assume that they would affect PCM and DD streams equally.

Does the 565 have a tape bypass? Would that be unprocessed and therefor faster do you think? Of course I don’t know what would come out of it if there was a dd or dis signal but it could go to a different input on your pre maybe?

The 565 does have a digital bypass but that would be of no use since the 818v3 cannot process a DD/DTS signal.

The Sky+HD box has both digital optical and co-axial outputs but they both deliver the same stream type. Setting the box to PCM makes it output stereo PCM (which I believe is broadcast as a separate stream from the DD and not mixed down on board - I don't know how terrestrial TV is broadcast or how TVs do things) for all channels. Setting the box to DD outputs DD 5.1 or DD 2.0 for channels with those streams and stereo PCM for those channels which do not.

I would be interested to hear your results if you do try this out.

How does the 818 deal with dd or dts material? Does it recognise that it can’t decide it and stays silent, or does it spray white noise over your speakers? If the latter then it’s clearly not a go-er but if it’s the former then it could be a separate input which you might choose to switch to when there’s a pcm stream?

I’ll have to find some time to test this myself, but it would be easier if the TV had 2 optical outs and then when my wife switches the tv on, everything is fine and this would just be for me to play with

Just a question but why not run the 565 into D2 on the 7200's? That way latency and lip sync are minimalized.

Yes I realise that This is a learning exercise. Though hopefully the 818v3 is adding some special sauce.

I would however have to change the speaker wiring from star to daisy-chain and configure the master speaker for the relevant input(s).

Gianni,

I can tell you from recently running the 565 Z3 V6.0 for a couple of months that they do affect them equally. The time alignment done in configuration is applied to the output of Discrete Digital, Analog Stereo and Analog Surround material out of the 565.

FWIW, I experienced no such time alignment issues watching TV receiving PCM or DD via the Optical Output from my Smart TV. The Cable Box is hooked up via HDMI directly to the TV and I use the TV's SPDIF Optical output into the 565.

Perhaps try doing the same on your 565 if you are plugging it in directly from your Sky STB's Optical/Dig Coax SPDIF out... assuming it has an HDMI output to send to your TV and if your TV has an Optical out. I'm not familiar with Sky boxes since I'm not from the UK but I'd imagine most of them have similar connectivity to US digital cable boxes.

If you can do this, just make sure you set your TV's digital output settings to output all compressed audio without change (aka DD 2/0 or 3/2.1) otherwise it will by default convert everything to Lt/Rt PCM 16/48 which you don't want as you want the 565 doing the Lt/Rt downmix.

That's a pretty neat idea you came up with to use your 565 again. It's an awesome sounding processor for any use and I think it will serve you well in this re purposed usage.