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[mwillems]

So I read through some previous discussions about this issue, but I'm not sure I found the answer to my specific question.  When outputting to 5.1 or 7.1 or any other output with an LFE channel, does JRiver discriminate between LFE information and bass information re-rerouted from other speakers (bass management), and make sure that LFE information is 10 dB up over redirected bass?  If so, when does that happen in the signal chain?

I'm using a sub for extremely low bass reinforcement and LFE almost exclusively (my mains are 3 dB down at 25 Hz).  So my setup is (functionally) a 2.1 setup, but I also need two extra channels for bi-amping.  So, I'm currently outputting in "stereo in a 5.1 wrapper," and "creating" a sub channel for myself in PEQ by copying the mains and using high and low pass filters to create the appropriate frequency response characteristics.  And that all works great frequency-wise, but I'm trying to do volume calibration for the sub and am confused.

Three questions:

1) When downmixing surround content to stereo what happens?  Is the LFE mixed in at a higher volume so that the 10 dB gain for LFE information is "baked in" to the stereo signal? 

2) Assuming that the situation I've described in 1) is correct, what baseline do the calibration clips use?  For example if I'm using the stereo calibration clip with -20dB pink noise, do I want my sub to be at the same RTA single octave reference level as the speakers?  Or do I want it to be showing 10 dB up?  I understand that sub calibration is more complex than all that, but I'm just looking for a rough sense of what level I'm even shooting for at step one. 

3) If I find a way to re-rig my setup so that I'm using an output format that includes an LFE channel (I think 2.1 has some extra blank channels?), and use the band limited pink noise calibration clip for the sub channel do I want the sub even with the other channels or 10 dB up?

Basically I'm just trying to get a grip on what gain (if any) JRiver applies to the LFE information and at what step in the signal path that gain is applied (at output format, by room correction, not at all, etc.).

Thanks in advance for any info/advice.

[Matt]

does JRiver discriminate between LFE information and bass information re-rerouted from other speakers (bass management), and make sure that LFE information is 10 dB up over redirected bass?

Absolutely.  It wouldn't work right otherwise!

1) When downmixing surround content to stereo what happens?  Is the LFE mixed in at a higher volume so that the 10 dB gain for LFE information is "baked in" to the stereo signal?

Yes.  The proper +10dB calibration is preserved.

3) If I find a way to re-rig my setup so that I'm using an output format that includes an LFE channel (I think 2.1 has some extra blank channels?), and use the band limited pink noise calibration clip for the sub channel do I want the sub even with the other channels or 10 dB up?

For relative levels, try the 'Level' checkboxes in DSP Studio > Room Correction and get all the speakers to play at the same level.  It works for the subwoofer as well, but as you said, subwoofer levels can get more complicated if you're picky since you really only want something coming out the subwoofer if it's not coming out the mains (so you don't double-up).

For reference volume, use the 'Volume calibration' clip you're using.

[mojave]

So, I'm currently outputting in "stereo in a 5.1 wrapper," and "creating" a sub channel for myself in PEQ by copying the mains and using high and low pass filters to create the appropriate frequency response characteristics.  And that all works great frequency-wise, but I'm trying to do volume calibration for the sub and am confused.

You can mix the LFE into the mains using 2 channels (in a 5.1 container) or you can mix the rear surrounds into the mains using just a straight 5.1 output. Either way, I would recommend using Room Correction for bass management since it is a lot easier. Use the PEQ for the active crossovers for the mains. Here is how the second method would work:

Output Format
     -Channels:  5.1 channels (or you could even use 7.1 if you have 7.1 audio tracks)
     -Mixing:  JRSS with both options checked (for stereo sources, only mix to 2.1) and (move center to front L/R)
     -Subwoofer:  Silent
     -Note:  With both options selected, you will get now get either 2.1 or 4.1

Room Correction
     -Set your crossover for Left, Right, SL, SR with the appropriate frequency and high/low pass slopes. They aren't labeled, but the top slope is for the speaker and the bottom one is for the sub. I also would suggest you use "Move bass to subwoofer."
     -Use the distance and levels for Left, Right, Sub, SL, SR making sure the SL and SR are the same as the Left and Right. This is because you will later mix the left and right surrounds (or even rear surrounds if using 7.1) in the mains and you don't want to change anything between them.

Parametric Equalizer
     -Add Mix Channels and then add the left surround to the left speaker and the right surround to the right speaker
   
At this point you now have a 2.1 setup with the original LFE and rerouted bass from other channels all at the proper level. You have also mixed the side (and possibly rear) channels into the front channels. Now you can continue to use PEQ or PEQ2 to setup your active crossovers by copying channels, etc.

Make sure that your DSP chain has Room Correction first followed by PEQ and PEQ2. You can drag them around to change the order.

For strictly 2 channel sources you could make a different zone and use ZoneSwitch to switch to it. Matt feels that creating the subwoofer channel in Output Format is a little better for two channel than using Room Correction.

Now that I've typed all this, I'm not sure in reality if it will sound any different than just downmixing to stereo and starting from there. One thing you might experiment with, though, is not mixing the surrounds into the mains. The above allows you to easy check/uncheck the surround mixing in PEQ. Since the surround effects are supposed to be to the side and rear, I have found it distracting when they come out of the mains. This is especially noticeable when watching football or a concert and the crowd noise is coming out the front channels. The front 3 channels and LFE plus the redirected bass (using room correction) from the surrounds is sufficient most of the time and, to me, the dialogue and other front channel content is clearer and sounds better.

[mwillems]

Thanks a billion Matt for the quick response.  I think I've got it now.  I just wanted to be sure I understood because my sub is sealed and I'm pouring power into it to get decent low-frequency response. I've got plenty of power, but I'm xmax/displacement limited on the lower end, so I was trying to make sure that I have adequate headroom

As a check, to make sure I understand (and don't wind up shaking my sub driver apart):

Assuming everything is crossed over correctly (a big assumption) if I calibrate the level on the sub to the appropriate volume using the reference -20dB pink noise clip (and the relative level compared to the mains is correct), do I understand correctly that the top of the standard film LFE dynamic range will be 30 dB louder than that reference point (i.e. 113dB)?  

Obviously program material varies (music is mastered louder than film, etc.) and I'll need to do additional testing to ensure driver safety, but I just wanted to double check that my understanding of the basic math was correct for my own peace of mind.

Thanks again :-)

Now that I've typed all this, I'm not sure in reality if it will sound any different than just downmixing to stereo and starting from there. One thing you might experiment with, though, is not mixing the surrounds into the mains. The above allows you to easy check/uncheck the surround mixing in PEQ. Since the surround effects are supposed to be to the side and rear, I have found it distracting when they come out of the mains. This is especially noticeable when watching football or a concert and the crowd noise is coming out the front channels. The front 3 channels and LFE plus the redirected bass (using room correction) from the surrounds is sufficient most of the time and, to me, the dialogue and other front channel content is clearer and sounds better.

@Mojave- I may give that a try and see, especially as I plan to build my surround system one step (read speaker) at a time, and your approach would work better for "modular" surround building.  I haven't needed much room correction so far with only the three speakers which are roughly equidistant from the "sweet spot" (although I have had to use delay to get my bi-amped elements time-aligned).  So far the surrounds mixing into the fronts has sounded good to me, but I don't have a reference point (having very limited experience with true surround).  Most of my listening is stereo audio, though, so an extra zone will definitely be the thing.  

Thanks very much for the advice, as it answered some other lingering questions I had (as to whether the ala carte PEQ channel mixing was a good substitute for JRSS).