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[zydeco]

I’m running a stereo system with active left / right speakers as well as multiple subwoofers to smooth the in-room bass response. The set-up sees the JRiver output format set to “two channel in 7.1 channel container” with JRSS mixing enabled and native convolution used to create the cross-overs for the various main speaker and subwoofer speaker drivers. The reason for the post is that I’m thinking of adding a centre channel to for movies and TV (but don’t have the option of adding side speakers for a full 5.1 set-up due to the room layout meaning that left / right side speakers would have very poor WAF.) How would I accomplish this within J River in a manner that would work for both stereo and multi-channel sources (whilst maintaining the need for channels to be used for the various cross-overs to the left / right speakers and sub-woofers?)

[zydeco]

Any suggestions on the above question re. setting up a 3.1 system?

[mwillems]

You'll need to do some manual mixing to make it work.  My recommendation would be to use the following options:

In Output Format select: 1) 5.1 channels inside a 7.1 container, 2) JRSS mixing, 3) Check the box for "For Stereo Sources only mix to 2.1," and then 4) set subwoofer to "Silent"

That will do the following: mix all multichannel content to 5.1, and leave all stereo content alone.  The subwoofer option just controls what the JRSS mixer will do, it doesn't affect the LFE channel on material that already has one, which means that 2 channel will stay 2 channel, but the .1 on 5.1 will still carry through.

Then, in parametric equalizer, add the following filters at the beginning of you filter bank:
1) Adjust volume for L and R; -3dB
2) Use mix channels to add SL to L and SR to R each with a -3dB adjustment

Then just do your routing normally overwriting whatever was in your SL and SR originally.  

That should get you 3.1 with multichannel sources, and 2.0 with stereo sources.  If you are concerned about losing that 3dB of dynamic range on stereo sources, you can also just setup separate zones for stereo and multichannel and use zoneswitch to route audio.

One issue you may run into is that it sounds like you may be using multiple subs and/or using your subs for more than just LFE? If that's the case you'll need to do some additional manual routing/levelling for non-LFE content that's going to the sub, but you may already have that sorted out in your existing setup?  The main thing to remember is that LFE material needs to be 10dB louder than redirected bass from the mains/center.  So you want to add any redirected bass to the LFE channel(s) with a -10dB gain.  You may also need to reduce the volume of the LFE channel and any added bass by a few dB to avoid clipping (as shown for the surround mixing  above).

[zydeco]

That’s great – thanks for the comprehensive answer. The remaining question, as you mention, is how to deal with LFE and bass. My stereo set-up involves running the main speakers more or less full range (high-pass at 40Hz) and feed four subwoofers (spread around the room) with a mono bass. The low-pass and gain for each subwoofer channel has been set separately so as to get the smoothest response across a couple of locations over the 20 to 150Hz range.

I’m not sure how to deal with LFE and bass given this multi-sub set-up. At one extreme I could dedicate the subwoofer collocated with the main speaker speakers for the LFE channel with the other subwoofers given a signal that aggregated all the bass from the left / right / centre. The other extreme is to create a bass channel that is LFE + bass from left / right / centre which is then processed separately for each subwoofer.

The latter appeals as I wouldn’t have a subwoofer that is unused quite a lot of the time and I’m guessing that no switching be needed between different filters for stereo and home-theatre. Any advice on the best approach and how to execute that would be great.

[mwillems]

That’s great – thanks for the comprehensive answer. The remaining question, as you mention, is how to deal with LFE and bass. My stereo set-up involves running the main speakers more or less full range (high-pass at 40Hz) and feed four subwoofers (spread around the room) with a mono bass. The low-pass and gain for each subwoofer channel has been set separately so as to get the smoothest response across a couple of locations over the 20 to 150Hz range.

I’m not sure how to deal with LFE and bass given this multi-sub set-up. At one extreme I could dedicate the subwoofer collocated with the main speaker speakers for the LFE channel with the other subwoofers given a signal that aggregated all the bass from the left / right / centre. The other extreme is to create a bass channel that is LFE + bass from left / right / centre which is then processed separately for each subwoofer.

The latter appeals as I wouldn’t have a subwoofer that is unused quite a lot of the time and I’m guessing that no switching be needed between different filters for stereo and home-theatre. Any advice on the best approach and how to execute that would be great.

If your mains go down to 40Hz, I'm not sure you necessarily need to do much redirection for home theater purposes, but if you want to preserve all the bass, I'd advise using a filter bank like this (this assumes RL and RR are empty or unused channels during this portion of the filter bank):

Code: [Select]

Copy Left to RL with -4.8dB gain
Copy Right to RR
Add RR to RL with -4.8dB gain
Copy Center to RR
Add RR to RL with -4.8dB gain
Lowpass RL (you'll need to work out the appropriate slope and set point depending on the slope of your main's high pass)
Adjust Volume of Sub Channel -0.5dB
Add RL to Sub with -10.5dB gain

This will combine copies of the three channels with appropriate gain offsets (to avoid clipping), low pass them, and then add them back into the sub channel with an appropriate gain offset that also avoids clipping (the LFE is supposed to be 10dB louder than all content from the mains).

You might need to tweak the gains a little to taste, but this method should avoid clipping for the most part and should preserve the 10dB differential.