Film-Tech Forum ARCHIVE: SMPTE RP200

This is topic SMPTE RP200 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=003373

Posted by Antonio Marcheselli (Member # 373) on 04-30-2002, 01:00 PM:

I had a talk with Karen few days ago about a DTS question and I found for the first time that from Jan, 1st 1999 all movie released have the subwoofer track to follow the SMPTE RP200 rules so that the subwoofer track has to be 10dB in-band gain compared to screen channels.

So I've discovered that previous movie has subwoofer track 3dB louder (in DTS). Is the same for all digital formats? In other words, all movies released before 1999 will have digital (DD,DTS,SDDS) subwoofer 3dB louder? Or each formats had their standards?

On the other side, a sound system that hasn't been recalibrated since 1998 is now playing subwoofer tracks at -3dB?

Can someone enlight me about rhis question?

Bye
Antonio

Posted by Gordon McLeod (Member # 33) on 04-30-2002, 01:05 PM:

DTS raide the sub level to match the SMPTE standard that the others already followed

Posted by Antonio Marcheselli (Member # 373) on 04-30-2002, 01:31 PM:

Gordon,

Can you quantify the differences? 3dB for DTS is correct?
DD and SDDS encoded movie before 1999 are *all* following SMPTE standards? It is only a DTS change?

Antonio

Posted by Karen Hultgren (Member # 395) on 04-30-2002, 02:04 PM:

Our recordings have always matched the master mix. The 3dB difference on **OLD** DTS unit refers to the playback level from the player. Remember when the spec was to set the DTS output for 85dB SPL on screen channels, 82dB SPL on the surrounds, and 88dB SPL on the sub?

Now, the spec is to set the sub for 10dB in-band gain as compared to the center channel. It is best to use a RTA for this adjustment. If you do not have a RTA, you will be in the ballpark by setting DTS sub output at 91dB SPL.

Karen at DTS
khultgren@dtsonline.com

Posted by Karen Hultgren (Member # 395) on 04-30-2002, 02:06 PM:

This change is NOT a "DTS only" change. It is standard for DD and SDDS too.

Karen at DTS

Posted by Antonio Marcheselli (Member # 373) on 04-30-2002, 02:15 PM:

Karen,

Thanks for your clarification. I had few unclear question but I didn't want to buggy you more...

So before 1999 the level were 85-82-88 for Dolby Digital/DTS/SDDS?

And now are 85-82 and 10db in-band gain for SW for ALL digital formats?

Thx!

Posted by Gordon McLeod (Member # 33) on 04-30-2002, 11:54 PM:

No SRD and SDDS were always 10 db above or 90db

Posted by Antonio Marcheselli (Member # 373) on 05-02-2002, 02:33 PM:

Karen/Gordon,

Do you mean that RP200 is a standard now for all formats but before 1999 both DD and SDDS were already obey that standard?

In other words, will a pre-1999 movie playing +3dB on subwoofer track only in DTS or in DD/SDDS too?

Bye
antonio

Posted by Karen Hultgren (Member # 395) on 05-02-2002, 04:03 PM:

Before 1999 there was no agreed industry standard. That is why RP200 came to pass. So, no one dis"obey"ed anything.

Karen at DTS

Posted by Antonio Marcheselli (Member # 373) on 05-02-2002, 06:10 PM:

Ok, so let me reassemble the question: pre-99 DD/SDDS movies had already SW channel set at 10db In-band gain or were different? If different, how they set their SW before 1999?

Antonio

Posted by Antonio Marcheselli (Member # 373) on 05-03-2002, 01:09 PM:

Another question.

Can someone explain to me into details what "RTA 10dB in-band gain" means exactly?

I understood that means that the subwoofer channel has to set 10dB louder than stage channels but...

I never made an EQ I just saw many times a tech making them.

Correct me if I'm wrong. The correct procedure is:

- Set the center channel with RTA means have the top "line" of the graph at 85dB?
- Set the subwoofer channel so that the top of the sw's limited-band is at 95dB?

it is very important for me, monday I'll have our tech re-eq (finally) the theater and I would like to understand the procedure before he cames!

Thanks

Antonio