Originally Posted by G1Nger
I ran the test as you asked - used Transformers (lots of LFE) and your observation is correct. There was a noticable lower audio level all around not just with the SW when outputting PCM as compared to DD. I have no idea if this is normal when the PS3 outputs PCM or not. Perhaps others can comment? I normally watch TV, DVD and BD around -34.5. I had to turn it up to about -25 or so with the PCM output. Hope that helps.
LFE was developed for early film multi-channel implementations (Dolby 70mm, etc) to get a lot more oomph for some sounds (explosions, etc.) in movie theaters. The idea was to dedicate a single channel, to be serviced by a dedicated subwoofer, to handle only these sounds (up to 150 Hz).
That's how we get mind numbing rumble or explosions from movies. This dedicated channel was meant to go 10 db higher than the other channels which topped off at 105 db; this means the high end of the LFE channel is 115 db.
To avoid overloading anything along the way, it was decided to make it the responsibility of the receiver to know ahead of time that the LFE channel is meant to be 10db higher than the other channels. This means that, although the LFE range is up to 115 db, it is actually delivered at the same levels as the other channels, or 105db tops to the receiver. It is up to the receiver to make that final 10 db boost once it sees that the signal is an LFE signal.
In the case of bitstream, that boost is handled automatically, which is why you see bitstreamed explosions sounding "right". In the case of PCM, that boost may not be happening unless you explicitly go in and tell the receiver that the LFE signal is coming in low. You can look at the LFE channel settings in the 1019 (or 919) - --> Audio Parameter --> LFE and see if changing the setting to -10db fixes the issue.
In some cases, the receiver may lower all signals by 5db to give itself more headroom, in which case the right setting may be -15db.
There's also some impact of these settings if you're playing SACD disks, but let's get to that later. Anyways, this is why I prefer bitstream if possible.