Film-Tech Forum ARCHIVE: CP650 SPL settings

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Posted by Nathan Tarpley (Member # 4476) on 02-05-2008, 09:13 PM:

I did a search and, while I did find information on setting surround SPLs with a 650, I could not find an answer to this specific scenario.

I have a CP650 with a Cat790 board installed. The board is primarily there for the digital inputs, so EX is just along for the ride, however, the auditorium itself has no rear-wall surrounds and thus no BSL and BSR output. The question is this: Do I still set SL and SR to 82dBC, even though the BSL and BSR will not be contributing to overall SPL in 5.1 mode? Or do I perhaps add 1-2dB to these settings to compensate?

Thanks in advance.

Nathan

Posted by Louis Bornwasser (Member # 3063) on 02-06-2008, 06:13 AM:

The quick answer is yes and yes. After "readings" are taken, you should listen to a known print and make SUBTLE adjustments as you describe. The only constant is that L-C-R should be the same level, and L & R should have the same EQ.

Anyone who leaves the room without actually listening to what he has done is inexperienced. Louis

Posted by Nathan Tarpley (Member # 4476) on 02-06-2008, 09:35 PM:

I didn't want to give the impression that I didn't listen to house after an EQ, thus exposing my "inexperience." I certainly agree that listening to familiar material (ideally some 5.1 film as well as non-sync music) is an important part of the process. However, given that this is a digital only house, it can be difficult to find familiar "prints" with valid KDMs [Wink]

. Maybe using a familiar 5.1 DVD (via Dolby format 80) would be the best solution to this, but DVD soundtracks are usually remixed for home so maybe not.....

Thoughts?

Nathan

Posted by Ron Funderburg (Member # 4561) on 02-06-2008, 10:03 PM:

I have a real bug a boo about techs that never go in an auditorium and rely only on the test material levels! Louis is absolute right that you need to listen to how it sounds! The meters are great and the scope tells you a lot especially on optical but nothing replaces your ears!

Okay moving soap box back to under the chair!

Dolby Digital sound levels are remixed but not necessarily different enough to make it where you can't use it. You are listening to see that the output sounds right!

I had a friend in the business that had installed DTS with ES in it and the tech had finished the work. He asked me to come for a visit and hear his new system. Well were in their and something happened where a car run off the left side of the screen and you hear crashing sound only problem it was off the right side wall not the left. The left and right out got inverted when they came out of the DTS ex unit and the Tech hadn't actually put his head in and re-checked it when installed the unit!

Posted by Brad Miller (Member # 2) on 02-06-2008, 10:10 PM:

This is an interesting point. I have a compilation reel that I run at the completion of each tuning which permits me to further fine tune things just a bit. What are the D-cinema installers using? Surely they aren't using trailers.

Posted by Ron Funderburg (Member # 4561) on 02-06-2008, 10:34 PM:

Brad I to have a made up reel of trailers that I can put on a platter and run though to hear something I know. I have a DTS disk I keep to load in with the current stuff when I do that has the stuff on it!

I would think they could use some digital trailers not sure how those are delivered to the theaters for certain. I guess a DVD makes sense. I have a friend that lives a long way off that installs home theater systems he told me he has a special DVD disk to tweak the projectors and sound systems with!