Quick 5.1 to 2.0 (LoRo) Crash Mix Question...

[sunman]

Hey Sound Gurus,

I've got a 5.1 Comp of a 35mm film project, that I need to convert to a LoRo stereo file to be plopped in to FCP, for output to DVCAM.

You might be wondering, Why not make an LtRt (matrixed encoded)?. Well, don't have the SRS or other plug-ins. And no money in the budget to buy any auto-downmix plug-in tools.

My question is this. I have read many posts, on various forums, and cannot seem to find a concessus on the right levels to set for a Crash mix from 5.1 to LoRo.

If I bus my 5.1 mix, to MONO auxs inputs, then bus the MONO AUX inputs to a Stereo Bus output. How much lower must the CENTER channel be set at? What about the surrounds? and are the LEFT and RIGHT channels meant to be PANNED left and right, at full volume to their corresponding Stereo Bus outputs?

I'd really appreciate it, if someone could map out a NON PLUG-IN route for accomplishing a decent CRASH DOWN.

Thanks, you guys ROCK

Sunman

[georgia]

There are a couple discussions on this topic already on the DUC, but basically take your 5.1 MIX
and do the following:

L buss to L
C buss to L and R with a -3 db drop
R buss to R
Ls buss to L with a -3 db or -6 db drop ( depending on taste )
Rs buss to R with a -3 db or -6 db drop ( depending on taste )
LFE buss to L and R with a -9db drop ( you can also just turn this track off )( again its a taste thing and a technical decision based on your expected delivery( TV, beta tape, DVD ) and just how much LFE you are using. You don't want to blow the TV speakers up, or end up with a significant amount of energy in your mix that will never be heard.

Double check your mix if you've got any seriously out of phase stuff going to the rears that might now impact your folddown mix.

This will give you an LtRt mix. But it'll do. A real LoRo Mix is just that. a Stereo mix. You'll need to go back in a re-mix in stereo. I do this for any broadvast projects since the majority of the world is still listening to stereo on TV sets, and I want them to hear what I really meant.

cheers
geo

[sunman]

Hey Geo,

Thanks for the info. The reason I posted is that in the various previous discussions on the DUC
there seemed to be conflicting advice regarding this procedure. Here's an excerpt of a post on this bulletin
by a mixer from Los Angeles:

"I would set the LCR inputs at zero of course, with the surround channels at -6db to start and the LFE at zero to start (remember, it's already down -10 because of the gain at the LFE amp) and adjust by ear to taste. You also might need a limiter on the LtRt, but you'll have to determine that. "

I realize that there is a certain element of subjectivity (taste) to this, that is why I was trying to see if there was some kind
of a concessus (or mathematical reasoning) for dropping the Center channel, and dropping the LFE in particular.

Peace,

Sunman

[minister]

one reason for dropping the center is pan law.

one reason for dropping the LFE is headroom.

you are cramming 6 channels into 2.

there are no RULES.

start with geo's or filmmixer's advice and then use your ears and GO GO GO!

[airon]

I'd like to chip in a question here too.

Are TV versions sometimes 5.1 DD decoded with normal dyanamic compression to Dolby Surround ?

I listened to a few TV broadcasts of films recently, and it sounds like they did exactly that. Does this happen a lot, or am I totally mistaken?

[minister]

Are TV versions sometimes 5.1 DD decoded with normal dyanamic compression to Dolby Surround ?

not sure i understand the question.

by Dolby Surround, you mean LtRt=LCRS=Pro Logic?

the LtRt (or 2) is derived from the 6, and, yes, sometimes dynamic compression is applied to make the LtRt. but this is pre-decode.

if you mean dynamic compression on decode, then no. dialogue normalization may lower the volume of the audio, depending on how it was encoded.

sometimes a separate TV and/or DVD mix is made to fit those mediums and playback requirements.

[airon]

Indeed, I meant LtRt. Thanks.

[D_Whiz]

Geo and Tom have summed up the basic setup for you.

From there its completely down to the dynamics or the average level that the soundtrack of the film is following and how your ears like it? There is no fixed rule when it comes to liking what you hear !

[TLmix]

one note...

A stereo panner in PT will lower the level -3db, so you should not have to pull down the center channel.

[minister]

one note...

A stereo panner in PT will lower the level -3db, so you should not have to pull down the center channel.

it is 2.5