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[flac.rules]

The sound seems to be pretty bass-heavy, so I checked if the LFE-channel has the right level. In the analyzer the LFE-part seems to have the same level as the rest. Is this compensated for the LFE-level-boost? So it is actually outputting LFE 10 dB lower as it should? Or is the LFE to high in my case? If so, how can i fix it?  (I mix everything to 5.1 inside 7.1 container, an have the subwoofer setting at 120 Hz crossover).

[Hendrik]

The analyzer shows the signal as its being output, as the final stage of DSP.

For LFE, its suppose to be output 10dB louder then its encoded in the file, not 10dB quieter, for what its worth. The purpose here is to have one channel that can hold its own volume wise against up to 7 channel of high frequencies, thats why it gets the volume boost - not a reduction.

[flac.rules]

The analyzer shows the signal as its being output, as the final stage of DSP.

For LFE, its suppose to be output 10dB louder then its encoded in the file, not 10dB quieter, for what its worth. The purpose here is to have one channel that can hold its own volume wise against up to 7 channel of high frequencies, thats why it gets the volume boost - not a reduction.

The output to the receiver should be 10 dB lower (with a flat frequency source), because it will boost the signal 10 dB. In other words, JRMCs output of the LFE-channel should be 10 dB lower. But if it is not, what might be the case?

[Hendrik]

It should not be lower then the main channels, it should if anything be equal, or higher if you output to a simple DAC instead of a receiver. Otherwise the entire boost by 10dB logic is useless. Why design it to be lower just so its boosted again? Instead its designed to be equal and boosted on top of that.

As mentioned above, the boost is designed to allow a single LFE channel to produce more volume then the main channel can, so that it has enough power to compete with the main channels. If multiple channel play the same sound, the volume increases, and a single LFE channel would never have enough power to compete with that - unless it gets extra boost.

A player like Media Center should never actually decrease LFE. It should either increase it by 10dB, or leave it alone if that increase is being performed somewhere else, but never decrease it.

[flac.rules]

It should not be lower then the main channels, it should if anything be equal, or higher if you output to a simple DAC instead of a receiver. Otherwise the entire boost by 10dB logic is useless. Why design it to be lower just so its boosted again? Instead its designed to be equal and boosted on top of that.

As mentioned above, the boost is designed to allow a single LFE channel to produce more volume then the main channel can, so that it has enough power to compete with the main channels. If multiple channel play the same sound, the volume increases, and a single LFE channel would never have enough power to compete with that - unless it gets extra boost.

A player like Media Center should never actually decrease LFE. It should either increase it by 10dB, or leave it alone if that increase is being performed somewhere else, but never decrease it.

It is designed to give higher headroom, so you can have a louder LFE channel, because LF is often loud, and noise is less of an issue. So it is a fair trade-off. One can discuss the logic in a digital setup, but it doesn't change the point, the receiver boosts the LFE-channel 10 dB no matter what one believes the original reason to be, so it should be output 10 dB less than it normally would.

If MC leaves the LF-data unchanged when it generates the LFE-channel, the volume will be wrong.

[mattkhan]

Some (many?) AV processors have a config option for whether it changes the lfe level or not.

Ultimately there is no one right setup for this as it depends on the entire playback chain.

[flac.rules]

Some (many?) AV processors have a config option for whether it changes the lfe level or not.

Ultimately there is no one right setup for this as it depends on the entire playback chain.

The majority do not, and all of them boost by 10 dB by default, since that is the standard used in all movies. There is one setup that is vastly more useful, and that is the standard movie-setup almost every single receiver adheres to.

[Hendrik]

In any case you can adjust every channels levels with room correction or PEQ, but I don't believe MC is doing anything wrong either way.

Search the forums, this has been discussed multiple times already. If MC is decoding a LFE channel from a file, its supposed to be 10dB quieter in the file already, and not be reduced in volume by the player. You don't get headroom from artificially creating it, its only useful if it exists in the file so it can already use it.

[flac.rules]

In any case you can adjust every channels levels with room correction or PEQ, but I don't believe MC is doing anything wrong either way.

Search the forums, this has been discussed multiple times already. If MC is decoding a LFE channel from a file, its supposed to be 10dB quieter in the file already, and not be reduced in volume by the player. You don't get headroom from artificially creating it, its only useful if it exists in the file so it can already use it.

Exactly, it is supposed to be 10 dB quieter in the file, which is why when MC generates the LFE-channel, it should do the same. If you ajust the channel, the "native" LFE-channels will be wrong.

[RD James]

Receivers are only supposed to amplify the LFE channel by 10dB if they are receiving an encoded format such as Dolby/DTS.
PCM inputs are not supposed to amplify the LFE channel by 10dB - though some receivers may optionally let you enable it.
 
Thus, if Media Center is decoding the signal to PCM, it should boost LFE by 10dB.
Well, it should really be reducing the gain of all the other channels by 10dB since boosting the signal by 10dB could potentially cause clipping.

[flac.rules]

Receivers are only supposed to amplify the LFE channel by 10dB if they are receiving an encoded format such as Dolby/DTS.
PCM inputs are not supposed to amplify the LFE channel by 10dB - though some receivers may optionally let you enable it.
 
Thus, if Media Center is decoding the signal to PCM, it should boost LFE by 10dB.
Well, it should really be reducing the gain of all the other channels by 10dB since boosting the signal by 10dB could potentially cause clipping.

Yeah, that is fair enough, because in PCM there is no standard that dictates that is should boot the LFE-channel. The point is that it should be consistent. The "generated LFE" should be the same level as a "native LFE" (that is -10 dB on the movie format, not -10dB if it is LPCM), but i got the answer i was looking for i guess. The analyzer shows the levels as they are output to the receiver.

[dtc]

If you bitstream a Dolby/DTS signal, presumably the LFE output is exactly as in the file.

Otherwise, I agree with RD. Undecoded Dolby/DTS signal should not have LFE boosted, decoded Dolby/DTS should be boosted.