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Author Topic: Rise volume in phantom (center) channel Surround sound. Please read ....  (Read 4333 times)

jorsan

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I would like to know if its possible to rise the level of the center channel signal in a configuration where no center channel is used in a surround configuration. Let me explain: I do not have center channel in my system, so in my actual JRiver configuration this signals are redirected to my mains left and right. In the majority  of the movies that I play, I would like to have the dialog volume about 2 dbs above the actual level of my left and right speakers; don't know if I can do this within JRiver with no center channel in use. Your input will be appreciated. Thanks   
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Matt

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There's no way to control the volume of the center with JRSS mixing.  It's going to put the center in the left and right in an energy neutral way (the right way).  Sorry.

You could turn the volume up of the entire thing and the center would get boosted too.
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Matt Ashland, JRiver Media Center

Trumpetguy

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In Player>DSP studio>parametric equalizer you can add/move/etc your center speaker to other channels. Here you can also apply gain in dB.
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mwillems

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In Player>DSP studio>parametric equalizer you can add/move/etc your center speaker to other channels. Here you can also apply gain in dB.

That works, but only if JRSS mixing is not used.  If you use JRSS, then the center is gone by the time you get to PEQ. 
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jorsan

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Matt, thanks fore the prompt response. Can I assume that if I configure my left / right front speakers for example to 10 dbs, the center will be in the same 10 dbs, and if I rise them to 20 dbs the center will be boosted to 20 dbs also?; in other words the "panthom" channel always be in the same level as the mains left/right?.
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jorsan

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will try that, thanks Trumpetguy and mwillems ... great help
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mwillems

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will try that, thanks Trumpetguy and mwillems ... great help

Just to be clear, what Trumpetguy is describing is doing your own custom downmix using PEQ.  Once JRSS is turned off, there's no automatic downmixing going on, so you'll need to do whatever downmixing is necessary for your system in PEQ.
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jorsan

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thanks mwillems but do not need to downmixing. I have a 7.1 system (well, 6.1 because no center channel) in this zone so I consider downmixing no neccesary.
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mwillems

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thanks mwillems but do not need to downmixing. I have a 7.1 system (well, 6.1 because no center channel) in this zone so I consider downmixing no neccesary.

Ah good, that's the best case for this kind of thing, the only downmixing you're doing is the center!  You can just turn JRSS mixing off and do what you need to with the center channel.
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jorsan

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great, thanks for your help
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jorsan

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Ok, I just reconfigure my system and want to be sure that I have done it in the correct way:
1.- No downmixing.
2.- In parametric eq. I add "move center to right +2db" and "move center to left +2db" ... is this the correct way to create a "phantom" center channel and to rise the level of this center channel +2 dbs comparing with main left and right?
thanks in advance
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mwillems

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Ok, I just reconfigure my system and want to be sure that I have done it in the correct way:
1.- No downmixing.
2.- In parametric eq. I add "move center to right +2db" and "move center to left +2db" ... is this the correct way to create a "phantom" center channel and to rise the level of this center channel +2 dbs comparing with main left and right?
thanks in advance

Several issues: 
1) You want to use "add" not "move" or you'll lose your normal left and right channels.
2) That method will produce a phantom center much louder than +2dB because the sound will sum.  The center only normally plays out of one speaker, you're playing it out of two.  If you add the center to the left and right with no volume changes it will already be at least +3dB (probably more) relative to the left and right.  I would advise adding it with no gain to start and then tweaking until it's how you want.
3) You'll need to take the global volume level down (on all channels) by a few dB to provide digital headroom for the channel summing you're doing.  JRSS does this automatically.  It won't be the end of the world as long as you have clip protection on, but it's advisable to turn everything (all channels) down by a few dB.  If you use internal volume and don't keep it maxed, you can probably ignore this piece.
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jorsan

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thanks again mwillems, I follow steps 1 and 2 .About the 3rd, do you consider better to activate JRSS?, I dont use internal volume .... IM little lost here ... ?
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jorsan

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is there any way to calibrate the center "phantom" channel level comparing to the mains left and right?
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mwillems

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thanks again mwillems, I follow steps 1 and 2 .About the 3rd, do you consider better to activate JRSS?, I dont use internal volume .... IM little lost here ... ?

If you turn on JRSS, you can't mix the center yourself, so then you're right back where you started.

Downmixing is a little complicated; the issue is that adding two channels makes the new summed channel louder than either channel was by itself (like two instruments playing at the same time instead of one), but there's only so much digital "headroom" to go around and that summing can cause clipping.  If you don't use internal volume (which provides digital headroom), you need to add a parametric equalizer "adjust the volume" filter turning down the volume on all channels by -3dB.  That should give you enough headroom.

So your parametric equalizer will look like:

1)Adjust the Volume -3dB (all channels checked)
2) Add Center to Left
3) Add Center to Right.

Then watch something and see if the center sounds like a good volume to you.  If you want it louder, add some boost to the center and see if it sounds better, etc.

is there any way to calibrate the center "phantom" channel level comparing to the mains left and right?

You'll need a dB meter or a calibrated microphone to do a real calibration.  Otherwise you'll just need to do some rough math and use your ears. 
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jorsan

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thanks for the detailed information. Will follow your recomendations and try it to see if I like the results.
 
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mojave

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is there any way to calibrate the center "phantom" channel level comparing to the mains left and right?
Use JRSS and check "move center to front L/R".
Click Load/Save at the bottom right of DSP Studio and save the DSP as JRSS Phantom Center.

Uncheck "move center to front L/R". (I still recommend leaving JRSS on to upmix 5.1 content to 7.1, but you can also turn it off if you want. If you don't uncheck the phantom center first, I think there is a bug that it will still be phantom even when turning off JRSS.)
Create the phantom center using the instructions provided by mwillems. I would add the Room Correction DSP before the PEQ to make it easier to adjust the center volume. Then just mix at 0 dB when moving the center to L/R.
Click Load/Save at the bottom right and save the DSP as Custom Phantom Center.

Go to Tools > Advanced Tools > Audio Calibration > Volume Calibration and set it to 7.1 and 48 kHz. Press play (don't press create files).
Advance to the center channel test.
Open DSP Studio and load the JRSS Phantom Center and listen to the volume level.
Now load the Custom Phantom Center. Use the Room Correction DSP and adjust center speaker level until until it sounds just like the JRSS mixing. You may have to switch back and forth between your saved DSPs until you get it close. Now you have a baseline for what is correct. You can bump up the center volume in Room Correction easily to suit your taste.
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jorsan

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wow mojave, looks like I will find "nirvana" very soon. Will try all this tonight and keep you all posted. thanks a lot
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