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The twk88 can do differential rear fill. A friend of mine told me how to set it up. I did and can verify it works. :)




Edit: FWIW, I'm not seeing any posts in this thread having been moderated so it must be something with the site today.
Do you mind posting this info? I'm trying to help my friend with his VXI amps to do rear fills properly. Not sure how to do the routing.
 

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Did you ever figure this out on the VXi? I am curious as well :cool:
I played with this for the first time today. Here is what I came up with in my VXI amps:

For the left rear:
Go to setup. Tie your input L&R together on the mixer and route that to left rear. Open the mixer path EQ for that left rear. Set +polarity -6dB on the left input, and -polarity -12dB on the right input. Go to Tuner. Set your crossover to bandpass 80Hz to 4kHz. Then go to delay/polarity and set total delay to -20ms. Under output I also trimmed -6dB.

For the right rear:
Go to setup. Tie your input L&R together on the mixer and route that to right rear. Open the mixer path EQ for that right rear. Set -polarity -6dB on the left input, and +polarity -12dB on the right input. Go to Tuner. Set your crossover to bandpass 80Hz to 4kHz. Then go to delay/polarity and set total delay to -20ms. Under output I also trimmed -6dB.

Mine is a little more complicated as I'm running active tweeter and mid in the rear, but that is basically just doubling the above steps and setting different crossover points.
 

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Did you ever figure this out on the VXi? I am curious as well :cool:
This is what I could remember. Test it out yourself and adjust level, crossover points and delay to your liking. Every car is diff.





Sent from my iPhone using Tapatalk
 

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Thanks Audi/Tony! Carlos from JL just got back to me as well and told me basically the exact same thing. Will give this a shot! Thanks again for the help as always!
 

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This is what I could remember. Test it out yourself and adjust level, crossover points and delay to your liking. Every car is diff.





Sent from my iPhone using Tapatalk
Hm. When I did the routing like yours under mixer path EQ4 with L input pos polarity / -6db and right input neg polarity / -6db I got no sound. I had to make a difference between the inputs (ie set the right input to -12dB).

I also have my polarities the opposite of you under the idea of trying to make the L rear be L-R. Rear left I have as +L input and -R input.
 

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Hm. When I did the routing like yours under mixer path EQ4 with L input pos polarity / -6db and right input neg polarity / -6db I got no sound. I had to make a difference between the inputs (ie set the right input to -12dB).

I also have my polarities the opposite of you under the idea of trying to make the L rear be L-R. Rear left I have as +L input and -R input.
Oh my goodness. I am glad you posted this photo cause now I realized why I had no sound: I was listening to mono pink noise at the time so both channels had identical information ;-) I will change the settings!
 

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Lol easy mistake.


Sent from my iPhone using Tapatalk
 

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Hey all, so I set up the +L -R in my truck and it sounds pretty cool but it is not very noticeable, even with level cranked up. Is it safe to assume it is because my rears are low in the rear doors (2108 GMC Sierra quad cab)? My front stage is pretty f-in loud so that also could be it :)

How do you even go about EQ-ing a setup like this? Just curious... or does it even matter? Thanks!
 

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Hey all, so I set up the +L -R in my truck and it sounds pretty cool but it is not very noticeable, even with level cranked up. Is it safe to assume it is because my rears are low in the rear doors (2108 GMC Sierra quad cab)? My front stage is pretty f-in loud so that also could be it :)

How do you even go about EQ-ing a setup like this? Just curious... or does it even matter? Thanks!
It's not supposed to be noticeable, if done right.
 

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I'm planning on trying out some rear fill on my fresh install I'm working on for my 2000 Honda Insight. The hybrid battery has been removed and I'm doing a completely new trunk. Tiny hatchback... thinking about aiming the two rear speakers rearwards. I'd assume this is more preferred than, say, upfiring or forward firing? Or maybe put them in the rearmost of the trunk, forward firing?
 

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And it’s just my opinion that L-R methods don’t sound good
It reminds me of the hirem effect in a matrix surround from the 60s


It sounds dumb and boring in my humbleness


Seems to me we need to see a rear processor that has some reverb , decay , detune , twotap echo , all user defined .


TLDR I’m not a proponent of L-R rear fail
 

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And it’s just my opinion that L-R methods don’t sound good
It reminds me of the hirem effect in a matrix surround from the 60s


It sounds dumb and boring in my humbleness


Seems to me we need to see a rear processor that has some reverb , decay , detune , twotap echo , all user defined .


TLDR I’m not a proponent of L-R rear fail
Glad to hear all opinions! I am programming different rear fill options as presets and trying them all to see which I like best. Is there a configuration that you prefer that can be accomplished with a normal DSP? (I have a JL VXi) Thanks :)
 

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Glad to hear all opinions! I am programming different rear fill options as presets and trying them all to see which I like best. Is there a configuration that you prefer that can be accomplished with a normal DSP? (I have a JL VXi) Thanks :)

For rear fill I like to use delay and make the rears reinforce the fronts
Just normal tape measure distance should do it the rears should “disappear “ and help create the center and staging

I also put a shelving filter or a 1st order low pass starting around 150-200hz
To get some of the mids so it’s immersive but it’s not talking so much.


As far as L-R , it works, I just think it sounds fake and not realistic, so without the proper fill tools I just use them as normal speakers and cut the highs really
 

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I'm with oabeieo, I don't like rear fill, even when done "correctly". It's personal preference, but even if it's done L-R, bandpassed, delayed, attenuated, etc. it is still artificial. I listen to a lot of music with headphones and some decent stereo speakers at home, so my standard is stereo, hearing any rear fill sounds really off to me (and it is off).

I can appreciate why people like differential rear fill, but it's not for me.
 

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Thanks for the input guys. As this is my first mobile audio project (besides the random sub I crammed into the extended cab of a 1994 GMC sonoma back in the day!) it has been fun just trying to figure out exactly what I actually like.

I have been plugging ideas that I get from you pros into my DSP as presets and then basically just playing 'preset roulette' by randomly selecting a preset without looking to see which setting its on to just let my ears try things out to different music, then recording my thoughts. Since I spend a lot of time on the road for work I get plenty of time to "test". Tonight I'll plug in something like Oabeieo mentioned and see where I am when I get home. Thanks again
 

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I've been trying "fronts only" since I installed a new amp and DSP and after over a month of playing with MANY different target curves and EQ, I've finally given up on "fronts only". I just do NOT like the way it sounds. To me, it sounds "thin" and just "bland" when compared to having the rear speakers playing as well. I have the rears at a lower level and band-passed. Still experimenting with different combinations, but right now, I have the rears band-passed at 75hz/7000hz, and EQ'd in a way that the frequency response goes "down hill" as the frequency increases - and I like the "fullness" it gives the sound. You don't actually hear the back speakers - meaning you don't even realize they are on - until you turn them off. :) With this type of setup, the vocals still come from the windshield, but you just get a much "fuller" sound. I just can't get used to "fronts only".

In my case, "fronts only" are 6x9's in the bottom of the doors and 3.5" coaxials in the dash, facing directly up into the windshield.

In the end, it all boils down to what *you* like and prefer. :) Obviously, my setup isn't "correct" in terms of a "SQ" install, but it makes me happy this way, which is what is important.
 

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I've been trying "fronts only" since I installed a new amp and DSP and after over a month of playing with MANY different target curves and EQ, I've finally given up on "fronts only". I just do NOT like the way it sounds. To me, it sounds "thin" and just "bland" when compared to having the rear speakers playing as well. I have the rears at a lower level and band-passed. Still experimenting with different combinations, but right now, I have the rears band-passed at 75hz/7000hz, and EQ'd in a way that the frequency response goes "down hill" as the frequency increases - and I like the "fullness" it gives the sound. You don't actually hear the back speakers - meaning you don't even realize they are on - until you turn them off. :) With this type of setup, the vocals still come from the windshield, but you just get a much "fuller" sound. I just can't get used to "fronts only".

In my case, "fronts only" are 6x9's in the bottom of the doors and 3.5" coaxials in the dash, facing directly up into the windshield.

In the end, it all boils down to what *you* like and prefer. :) Obviously, my setup isn't "correct" in terms of a "SQ" install, but it makes me happy this way, which is what is important.

Sounds like it’s done right. But it’s easy. Basic TA gets you there.

That’s great tho, yeah I like that same type of sound from rears also
I don’t care for anything much past 800hz coming from behind me
But I’ve heard systems with full range rears that’s are great
 
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