Downmix 5.1 stereo question


I did mix for documentaries in stereo for years. I’m trying 5.1 working on some projects (that still want just stereo so far…) and want to downmix 5.1 to stereo.
So i have all dialogues in C music in quadro, ambiances in quadro etc on some folley in the C when they follow action on screen. all these kind of things.
My speakers are calibrated 78db (following the broadcast recommendation i’m working for now) although… -23lufs for dial is quite loud I have to lower my monitoring to be comfortable.

I’m using the Downmix Presets from the Control Room to switch from 5.1 to stereo.
When I do so i feel a boost in overall loudness. So i set the “MixConvert” for stereo at -3db Global Gain. When I do so, the Dialogues in C feel at better loudness when sent to LR for the stereo downmix. But then I have the feeling the M&E a bit behind like 3db.
I wonder if i’m not doing anything wrong ?

Another way to see it is when i set the mixconvert for stereo downmix to these settings I feel switching from 5.1 to stereo is not ideal but closer :
center -6
Lfe -3
Surround -6
side 0
global gain 0

Why do i feel better with this -6 in center… i’m concern i’m doing something wrong somewhere. -3 seems the rule everyhwer i read.
how do you guys deal with this ?
do you mix in 5.1 and downmix in stereo directly with that preset or do you adapt the stereo version of your 5.1 mix.

I never used a straight downmix preset for any real delivery. In my world every project seems to need its own settings.

I simply adjust the tool used for the downmix (which is a dedicated mix bus in most of my setups, or sometimes just a matrix mixer) manually, using the instruments and speakers (and ears :wink: …) that I use for any “conventional” stereo mix

… but then, I mix music exclusively, not audio for media any more, so “dialogue” is not an issue for me.

Yeah I guess dialogue makes a big difference as intelligibility is key here. And psycho-acoustic perception can be different from mono C to stereo even if the rule of -3db should apply.

I think that the standard, if it exists, is probably Dolby’s;

Module 7.4 – Renderer Trim and Downmix Controls – Dolby Professional Support Learning

It has 5.1 to 2.0 in the LoRo preset as:

So that downmix seems like it would be closer to what you’d want. Last time I did an automatic downmix I too found it to be a bit ‘off’ with -6 from the surrounds, just a bit ‘weak’.

advanced link :stuck_out_tongue:
Yeah it could be something like that.
C at -3 is good of course else the -23lufs is lost on dialogues. Adding a bit more of the surround could be a good thing… but it’s not enough for the experience I have.
So I ended up doing a stereo version of the mix rather then a mixdown… but in the end just pushing the M&E by 3 dB in the stereo version and it sounds better with not much trouble.

If you find the time (and budget) to do so, it’s the best way to do it in any case. :slight_smile: That’s what I meant to say when I wrote that I feed a dedicated stereo-bus during my mixes.

I run all my sessions in a 5.1-bus with a second 2-buss and all tracks direct routed to both. I also have setup two “Monitor Sources” in the Control Room for 5.1 and 2ch (using same main L & R speakers). Most times, I bounce the mixes in 2ch, but like having a 5.1 mix ready if I want it. I toggle between the 5.1 and 2-bus as well as the Monitor Sources when mixing to make sure they sound the same - and mostly they do which is good because I don’t want to do two mixes. Mostly I’m mixing in 5.1 except to spot check the stereo mix.

This setup up also makes it easy to bounce a 5.1 mix and Stereo mix simultaneously. These are music sessions with all tracks recorded in mono or stereo.

I have been doing this for a long time and used to feel there was an issue with downmix.

One day I dug into it to see why the differences just in case I was doing something wrong, which is easy to do, and here’s what I found:

  • different dynamics or limiter settings on the 5.1-bus versus 2-bus - and this is tricky if you have your fav 5.1 limiter that has no 2-bus equivalent or vice versa (WAVES). I try to use the Steinberg dynamics lately since they’ll do either and can be setup the same.

  • panners - I like some of the other surround panners, but some can cause odd results if I recall correctly, so my default is the VST Multipanner. They also can freak out my RME using ADM.

So, check those things and make sure everything looks right and behaves as you like.

It can be useful to start with a very simple project with test tones to find out why Downmix is not doing what you expect. And if you still don’t like it, then customize it. I have not needed to change the default downmix settings since a good while. But I also have not used the “Mix6to2” plugin on the 5.1 bus explicitly in a long time either.

thanks for all that. Good to know you feel downmix is mostly correct.

yes, you’r right as I tested my speakers for 78dBc but I should also send test tone and compare it through the downmix… The dynamics and vsts i’m using are all 5.1 and there’s nothing after the downmix that would make a difference but you’r right i’ll double check that too.
also I wonder as you and Dietz are talking more about music (if I understood correctly ?) if having dialogues in the center is not part of my question here. making sure it’s -23lufs +/-1db but still intelligible might require some adjustments that are not the same as music (?) really not sure.