LtRt louder than 5.1???

[emilano]

Hey guys,

I'm using the surcode minnetonka dolby pro logic II encoder for a documentary film mix that will be going to theaters and broadcast. I'm a/b'ing between the 5.1 mix, the decoded LtRt and the encoded stereo LtRt. The stereo sounds a few db hotter than the 5.1. The decoded LtRt sounds a couple db softer than the 5.1. This is pretty consistent throughout. Is this common? Is there a way people typically correct for it?

Best,
E

[Postman]

That doesn't seem right, unless you have a whole lot of sound from the surround channels. Theater surrounds are set 3 db lower in playback level than the fronts, so surround channels would sound louder in the LtRt by 3db. The fronts, especially L and R, should be the same.

The stereo sounds a few db hotter than the 5.1. The decoded LtRt sounds a couple db softer than the 5.1.

When you say "stereo" do you mean the encoded LtRt, that you are playing through your left and right speakers? There really should not be a difference in overall volume when you switch between discrete 5.1, LtRt, or decoded LtRt (with the exception of the surround information as I just said). Have you checked levels to/from the LtRt using a sinetone. Something seems out of whack. A -20dbfs tone in the center channel of your 5.1 (nothing else playing) should make an LtRt that reads -23dbfs on each channel. That LtRt should decode up to a -20dbfs center channel again. If that is happening, there is something wrong about the way you are monitoring.

[rbeggs]

Your right about the levels. The decode function is 3dB short of providing unity output. It's now an acknowledged bug and will be fixed very soon. Your recorded LtRt is fine. Raising the gain after the decode output 3dB will make things right until the fix is in.

[rbeggs]

whoa,

Phone just rang and it was Minnetonka saying that the level fix update is on the way. So hang on, the fix is right around the corner.

[emilano]

Thanks rbeggs. What's strange is I think the surcode plug in has had this bug for years. Strange no one reported it earlier... So I assume the fix will make all 3 sound relatively similar (5.1 vs ltrt encoded vs ltrt decoded).

[Postman]

It's now an acknowledged bug and will be fixed very soon.

Strange no one reported it earlier...

My jaw hit the floor when I read rbeggs post that it is a bug. It must have been introduced in an update? How could no one have noticed for all these years? (I've never used Minnetonka's software!)

[emilano]

No, its something I've noticed for years. I don't mix very often (more lately) and have only used it a few times on mixes that were pretty low budget. Given my inexperience with LtRt's I didn't report it myself until now even though I've always noticed it with the Surcode plug. I thought that's how it was supposed to be... !

[philper]

I use the stand alone Minne PL II encoder all the time (PC), and have for for years, and have never noticed this. If I set the level of the C channel to tone to what I mixed as in the DAW (-20), and make sure the other channels are at the same level in the encoder then I get an LtRt that plays at the same average level as the 5.1 mix it came from. Or am I missing something? I assume you guys are talking about the RTAS version of the encoder?

Philip Perkins

[rhumphries]

I think it's the decoded LCRS that is off, not the encoded LtRt. I noticed this a couple weeks ago on a project, but though I was doing something wrong. I hadn't had a chance to check into it, so I'm glad this was brought up.

-Richard

[hef]

I have noticed this as well.