OK, I keep getting asked so here it goes.
To set your system up for the recommended DD theatrical range you just follow the prompts on the DVD. Forget anything you read anywhere else about compensation, 75dBSPL, and anything else.
This will give you a max of 115dB from the LFE at 0dBFS, and 105dB from all the other speakers individually.DTS is not recorded "HOT," neither are any DVDs. Most DVDs are dropped by -4dB. The ones that seem "Hotter" are just not as limited. There is no limiting on DTS (unless your processor does something funny.) Either way it is not "Hot," it just isn't attenuated by default.
Yes, some AVRs say +2 or -3 for DialNorm. These are setup where 0 on the screen(or no DialNorm screen in some cases) is actually -4dB below 0dBFS. In this case +4 is actually 0dBFS, and full loudness(DNR.) If you notice my DVD will pull up as +4. This is because there is no signal attenuation with my disk.
If you turn on Bass Management of any kind, and set at least one speaker to small you could get peaks above 115dB from your subwoofer. This is where it gets complicated.
If the sounds are not exactly the same this is called incoherent sound. There is a formula to figure it out but lets skip it. Lets assume this are 0dBFS level sounds;
If they are exactly the same they are coherent, and are a pain to sum, but here it is.
Now before you get too worried this is unlikely to ever happen. Why would you have full signal bass on every channel at the same time? There is also one other hurdle to clear, that never seems to get talked about.
Most people seem to know that the LFE channel is boosted +10dB. This is why 0dBFS is set at 115dBSPL on the LFE channel. What is mostly unknown is that before the crossover section in the process the LFE is digitally lowered -5dBFS, and is then boosted up to +15dB in an analogue output section to the RCA. All Bass Managed sound from the mains/surrounds are added in after the -5dBFS LFE step, and they are lowered by -15dBSF before being summed in with the LFE signal. (It is supposed to be boosted ~+15dB, but it isn't always.
What this means is that if a sound on the Front Right speaker was supposed to play back at 105dB, it will still be output at 105dB. The thing that is missed is that there is only enough digital headroom left on the LFE channel for +5dB. Anything over that will clip the DSP. This means the max signal from the LFE should be 120dBSPL. Anything else is clipped off. The mastering process should have fixed any gross offenders, so around +5dB plus an extra dB should be it. See below for the extra dB.
There is the problem of Digital to Analogue conversion where the DAC can create a signal higher in dBV than the dBFS. This is known as 0dBFS+. If this perfect storm of chance were to happen you could end up with a peak higher than 120dBSPL. This shouldn't happen with commercially produced products, but it could happen. (Sound guys are human too, and forget the lessons from the analogue world still carry over.) It would be an abnormal situation though.
For more info:
Dolby Section 3.5:http://www.dolby.com/uploadedFiles/z...Guidelines.pdf