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Discussion Starter · #1 · (Edited)
I thought this may be of interest.

I now have both DVE(HD DVD/DVD combo) and AVIA. So I was able to load them both into Sound Forge and check the dBFS levels. I did some more reading on Sound Forge and found a more precise way to check the dBFS levels using the Normalization feature where I can select a section to process and Sound Forge will tell me the 'Average RMS Level' in dBFS.

I used an Audio Extractor program to digitally transfer the DD 5.1 channel audio to 6 separate wave files at 24bit/48kHz and discarded the unneeded channels(this ensures no mixing has taken place).
The only thing I don't know is if the Dolby Dialog Normalization has any effect on this process, if it does then these figures may be after the offset is applied(but I can't confirm that)
FYI, my 3805 shows:
AVIA Dialog Norm OFFSET -4dB
DVE Dialog Norm OFFSET 0dB


I then loaded them into Sound Forge and used the Normalization function to read the RMS dBFS level of the selection(as seen in the timestamps)


AVIA
Left channel.....-23.6 dBFS (1-2sec) 1 second long
.......................-23.2 dBFS (1-59sec) 58 seconds long

Left ch HF........-23.6 dBFS (1-2sec) 1 second long
............LF........-25.5 dBFS (4-5sec) 1 second long

DVE
Left channel.....-36.4 dBFS (1-2sec) 1 second long
.......................-36.0 dBFS (1-9sec) 8 seconds long

LFE channel.....-32.8 dBFS (1-2sec) 1 second long
.......................-30.3 dBFS (8-9sec) 1 second long
.......................-30.9 dBFS (1-9sec) 8 seconds long

Just for reference,
Avia says the Main Channel tests should read 85db(C) on a SPL meter(the redirected sub tests are meant to read at equal levels and can be checked with level anywhere above 70dB),
DVE menu states that the 5.1 Multichannel levels are -30dBFS

cheers :)
Mods, please let me know if you would like anything changed in this post
 

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Discussion Starter · #2 ·
Over the weekend I did some thorough testing. I turned off the room EQ and used the receivers tones to set all channels to 75dBC. I then used AVIA and DVE tests and wrote down the dBC measurements for all the tests.

The BLUE dB levels are 'expected levels' worked out by taking the dBFS figures away from the in-room max SPL(105dB for mains and 115dB for the LFE). I actually worked these out after I did the testing.
The RED dBC levels are the actual measured levels after setting 75dBC with the receiver internal test tones

AVIA
Left channel.....-23.6 dBFS (1-2sec) 1 second long, 81.4dB, 81dBC
.......................-23.2 dBFS (1-59sec) 58 seconds long, 81.8dB

Left ch HF........-23.6 dBFS (1-2sec) 1 second long, 81.4dB, 81dBC
............LF........-25.5 dBFS (4-5sec) 1 second long, 79.5dB, 80dBC

DVE
Left channel.....-36.4 dBFS (1-2sec) 1 second long, 68.6dB, 72dBC
.......................-36.0 dBFS (1-9sec) 8 seconds long, 69dB

LFE channel.....-32.8 dBFS (1-2sec) 1 second long, 82.8dB, 83dBC
.......................-30.3 dBFS (8-9sec) 1 second long, 84.7dB
.......................-30.9 dBFS (1-9sec) 8 seconds long, 84.1dB

Everything seems close except for the 'DVE left channel' I re-checked the dBFS figures with the files on the PC and they came back with the same -36dBFS figure, and when I did the in-room tests they were definitely reading 72dBC. I might re-extract the files to the PC and see if there is a variation later.

The other thing is it seems that AVIA's dBFS figures are in fact post Dialog Normalization, so they seem to be mastered on the disc at the correct -20dBFS.

FYI, if you're trying to set/check the sub channel with AVIA's redirected bass tests you're better off using the bass component in the surround channels since the LF tones cover 35Hz-80Hz and if you have towers you will get some bass in the mains which will affect the SPL reading.

cheers :)
 
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