Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Why are cinema surround speakers set to -3Db?
#1
Is it to compensate for the fact that the front 3 speakers are behind the screen? And if so, is the intention that the audience perceives the levels as the same?

If this is true then the accepted wisdom that cinema DTS rips need to have their surround channels attenuated by -3Db for home viewing would be wrong.

It's interesting when looking at home mixes that are close to their theatrical counterparts as some apply the attenuation and some don't.
Reply
Thanks given by:
#2
In the theatrical environment the surround speakers are set to an acoustic sum to match each front speaker, this corresponds to -3dB. In the home environment speakers are all set to the same level so the incoming surround level should be attenuated. If I'm wrong please correct me
Reply
Thanks given by:
#3
I guess the pertinent question is how does the audience perceive the sound in the theater? Do the surrounds actually sound quieter than the fronts? Because at home a -3Db drop is going to be quite noticeable.
Reply
Thanks given by:
#4
Well the studio in which the audio is mixed is set to the same level so the audience hears what the mix engineers hear
Reply
Thanks given by:
#5
I guess that settles it then. Thanks for your insight. Smile
Reply
Thanks given by:
#6
IIRC the surround channel(s) is(are) set -3dB to compensate the fact there are many speakers for each channel(s) instead one for each in the front, so to let each speaker sounds a bit lower - think about viewers very close to side or back speaker - while when heard all together the summed level lead to the right one.

At home (if I'm not mistaken) it *should* be set 3dB higher than theater becasue any channel has its own speaker - unless we are talking about Dolby Surround (the original)/Pro Logic or EX or DTS-ES when a single channel pilots two speakers...

About the wrong level on some Cinema DTS (and subsequently laserdisc, where DVD were corrected AFAIK) it was one of the two, I can't remember which though:

- at the beginning studios sent mixes with same levels set, hence subwoofer 3dB and LFE 10db hotter
- first APT-X100 decoded (at home) decoded levels in the wrong way, then new versions corrected it
Sadly my projects are lost due to an HDD crash... Sad
Fundamental Collection | Vimeo channel | My blog
Reply
Thanks given by:
#7
It's 82db per channel, not per speaker. The left and right surround channels acoustically sum up to 85dB, it goes back to when surrounds were mono and carried over into the discrete age. Also room calibration almost invariably is based on an optimal listening position somewhere in the middle so viewers too far front/back/to either side will hear a less balanced mix.
Reply
Thanks given by:


Possibly Related Threads…
Thread Author Replies Views Last Post
  Cinema DTS - main thread spoRv 42 6,279 2021-11-21, 07:00 PM
Last Post: spoRv
  Dolby Surround decoding tests junh1024 13 358 2021-11-17, 01:24 PM
Last Post: spoRv
  The Myth of the Speakers: A Critical Reexamination of Dolby History spoRv 4 438 2021-07-18, 09:28 PM
Last Post: zoidberg
  What the hell is "2.0 Surround" anyway? pipefan413 31 3,332 2020-12-13, 11:31 AM
Last Post: zoidberg
  What is Cinema DTS? Hitcher 7 1,791 2020-05-28, 09:30 PM
Last Post: allldu
  CDS (Cinema Digital Sound) system overview spoRv 5 3,609 2019-11-28, 10:33 PM
Last Post: BDgeek
  Releases with theatrical surround-sound? deblock 8 3,136 2019-01-15, 08:17 PM
Last Post: spoRv
  [Help] Cinema DTS locomotive-like noise after 2 minutes? TomArrow 6 3,698 2017-12-12, 02:30 AM
Last Post: TomArrow
  The Past, Present & Future of Home Cinema. CSchmidlapp 26 15,767 2017-08-27, 03:46 AM
Last Post: captainsolo

Forum Jump:


Users browsing this thread: 1 Guest(s)