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Discussion Starter #1
I'm going with an active setup with 2-way components up front, coaxials for rear fill, and 2 subwoofers.
I'd like to stick with the helix mini-dsp for cost reasons but only have 6 channels with it. I've read that you can run the rear fill in mono on one channel and the subs on another channel.

What exactly does it mean to run the rear speakers in mono? Does it mean you can't adjust them individually (like time-alignment)? Is running them in mono an acceptable option so I won't be sacrificing all that much as opposed to each speaker having it's own channel?
 

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Just skip the rear fill my dude. No reason to half ass something that requires dedicated processing to pull off. Your other alternative is running the front components with the passive xover.

another option is to get a cheaper 8 ch dsp like a minidsp cdsp 6x8 for example.
 

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Discussion Starter #3
Just skip the rear fill my dude. No reason to half ass something that requires dedicated processing to pull off. Your other alternative is running the front components with the passive xover.

another option is to get a cheaper 8 ch dsp like a minidsp cdsp 6x8 for example.
I dig rear fill though, it gives me a more 'immersive' experience. What is it about running mono that makes it less ideal?
 

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I run a mono differential rear fill channel off a Helix mono output. Using this method gives me a much more immersive experience.

Watch SkiZers Youtube video #1 on setting up a Helix DSP. He goes over how to set up differential rear fill on a Helix DSP there.

Ge0
 
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Discussion Starter #5 (Edited)
I run a mono differential rear fill channel off a Helix mono output. Using this method gives me a much more immersive experience.

Watch SkiZers Youtube video #1 on setting up a Helix DSP. He goes over how to set up differential rear fill on a Helix DSP there.

Ge0
Thanks! So I'd be ok with the rear-fill and sub running mono on the last 2 channels? I'm actually leaning towards a Minidsp c-dsp 6x8 now - I'm hoping I still have the ability for this setup with that. I'll do some research on differential rear fill. Any idea where to find his video?
 

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If you only have one channel left for rear fill, you can flip the polarity of a speaker at the amplifier and achieve the same effect as L-R vs R-L. Make sure you add delay (8ms - 20ms) into the rear fill channel to help decorrelate it from the front speakers.
 

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If you only have one channel left for rear fill, you can flip the polarity of a speaker at the amplifier and achieve the same effect as L-R vs R-L. Make sure you add delay (8ms - 20ms) into the rear fill channel to help decorrelate it from the front speakers.
Interesting! I have a 7th channel either for center or it looks like possibly now rear fill... Did not know this method was possible! The results will be the same as having 2 channels for rear fill this way? Which speaker would you measure from? Can you explain it a little more in depth please? What about using the "real center" upmixer from my dsp.3 for rear fill?
 

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If you only have one channel left for rear fill, you can flip the polarity of a speaker at the amplifier and achieve the same effect as L-R vs R-L. Make sure you add delay (8ms - 20ms) into the rear fill channel to help decorrelate it from the front speakers.
He doesn't even need to do that. The DSP can do that for you in software. Just create a summed channel (Left 50%)+(-Right 50%). Route this to a single DSP RCA output. Apply your band limited cross-over, EQ, and time delay.

Ge0
 
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Interesting! I have a 7th channel either for center or it looks like possibly now rear fill... Did not know this method was possible! The results will be the same as having 2 channels for rear fill this way? Which speaker would you measure from? Can you explain it a little more in depth please? What about using the "real center" upmixer from my dsp.3 for rear fill?
The idea behind adding differential rear fill is to create a de-correlated channel with no center information to distract the front image. The rear channel is just ambient information from the music you are listening to. If you delay it you can increase the apparent size of your listening space.

The last thing you want to do is to apply real center to a rear fill channel. That would correlate and focus center information behind you which would shrink the size of your sound stage.

Ge0
 

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Have you set up and tuned a car system before? If not I wouldn’t even think about rear fill. Tuning a car and it SOUNDING GOOD isn’t something you just do quickly. There is a lot to it.
Rear fill is more advanced to have it work and sound good.
 
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He doesn't even need to do that. The DSP can do that for you in software. Just create a summed channel (Left 50%)+(-Right 50%). Route this to a single DSP RCA output. Apply your band limited cross-over, EQ, and time delay.

Ge0
I think there's a misunderstanding. My suggestion includes summing 50% left and -50% right in the software (this removes monoaural information), as well as flipping the physical polarity of one speaker at the amplifier (this decorrelates the rear speakers from each other). If you don't do this, all rear sounds will emanate from the closer speaker because the signal feeding the rear left and rear right are exactly identical (still considered mono). Flipping polarity will maximize rear fill stage width (which is what you want for ambiance).

R-L is the same as L-R, but with polarity reversed.
 

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I think there's a misunderstanding. My suggestion includes summing 50% left and -50% right in the software (this removes monoaural information), as well as flipping the physical polarity of one speaker at the amplifier (this decorrelates the rear speakers from each other). If you don't do this, all rear sounds will emanate from the closer speaker because the signal feeding the rear left and rear right are exactly identical (still considered mono). Flipping polarity will maximize rear fill stage width (which is what you want for ambiance).

R-L is the same as L-R, but with polarity reversed.
+R/-L and also physically flip polarity?
 
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+R/-L and also physically flip polarity?
He saying that no matter what processing you do to the signal when you're sending the identical signal to the left and right Phil speakers you get unwanted results

Sent from my SM-G965U1 using Tapatalk
 

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I’ve been reading a lot on rear fill and there seems to be different ways.
using two channels in the dsp-
Left channel +L/-R and right +R/-L

some say physically flip polarity of one...

is the way mentioned above +R/-L only using 1 channel in the dsp? And if so is this method as good as using two channels like I shown?
I only have 1 channel available in the dsp.3
 

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I’ve been reading a lot on rear fill and there seems to be different ways.
using two channels in the dsp-
Left channel +L/-R and right +R/-L

some say physically flip polarity of one...

is the way mentioned above +R/-L only using 1 channel in the dsp? And if so is this method as good as using two channels like I shown?
I only have 1 channel available in the dsp.3
Using two channels with +L/R- and +R/L- is the better way since each rear speaker will measure different in terms of frequency response (EQ), one will be louder than the other (individual level), and also be different distances away from the listener (delay). Using one channel would give you a slightly diminished version of the first method, but it would still be better than nothing. Although the differences may be hard to discern anyways.
 

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Gentlemen. I suggest you do some reading. All these topics have been discussed and resolved before.


Ge0
 

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It looks like the discussion of a L-R panned left plus R-L panned right was ended early due to technological limitations at the time of the discussion. Have things changed since then?
 

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It looks like the discussion of a L-R panned left plus R-L panned right was ended early due to technological limitations at the time of the discussion. Have things changed since then?
Yep. Now everyone and their brother owns a DSP capable of processing the proper signal. DSP's were still pretty rare back in 2007 / 2008.

Ge0
 

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First time caller, long time listener! As a newbie, there's a lot I still don't understand; however in my 2017 RAM 1500 with the factory Alpine system, the backup camera alerts come through the rear speakers. So even though I'm bypassing the factory amp with the PAC AMP Pro, I still need to have rear speakers. I'm guessing there are ways of rewiring things so that the alerts come through the front speakers, but that's not something I'm comfortable trying on a newer vehicle.

Also, in my case, I had turn the rear gain up quite a bit, in order to make the alerts loud enough. Ironically, once the gain is turned up, I can adjust the fader primarily towards the front, and it doesn't affect the volume of the alerts

Anyway, I wanted to point out that there may be situations where people need rear speakers.
 

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Could you keep your rear speakers in the factory locations for your alerts (they do come in handy don't they) but not route music to them? I ask because it may be possible to add a second set of speakers behind you for rear fill without altering the factory alert system. Just a thought...

Ge0
 
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