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I'm new here guys so here is the info on my build. I will be a bit long winded until I talk about my rear fill experience because I want you all to know everything about my system. About a month ago I had a shop install a Linkswell T style radio in the dash of my 2017 F250. I immediately noticed a huge difference in sound quality over my stock Sony radio.

Two weeks ago I returned to the same shop in which they installed Focal KX2 6.5 components in the front powered by a Helix P Six Dsp Mk2. I also had the cover both of the front doors with Soundskin as well as the using the soundskin speaker cover. In addition, under my rear seat they installed 2 10 inch Focal Flax P25 subwoofers(inside of a Foxbox) powered by a JL Audio HD 600/1 amplifier. Initially I had a JL Audio JX1000/1D but was told that would have been waaaaay too much power so I decided to return the JX1000/1D and utilize the HD 600/1.

Ok initially I wasn't impressed with the sound quality of the Focal Speakers so I was told give them a week or two so they could break in. In addition, I went along with their tune and never really tweaked anything.

REAR FILL EXPERIENCE:

Ok.........after the last install, I was told that until my speakers(Focal EC 165 coaxial) for the rear doors arrive, they would turn off my rear factory Sony speakers from the Helix DSP because the factory speakers will mess up my sound stage. So up until this past weekend I wasn't impressed with the midbass coming from the front speaker as they sounded too flat. So, I decided to use my laptop to access the Helix DSP and play around with the eq settings. After reading numerous different post and forums, I took my time and began adjusting some settings one speaker at a time and they began to WAKE UP! Then I decided to turn on my rear Sony stock speakers from the Helix and I was shocked as to how good they made my system sound. After spending several minutes adjusting their EQ settings and I was floored as to how well they sounded!

Afterwards, I spent time turning off and on the rear speakers to make a decision for myself as to the rear speakers messing up the sound stage. WOW, THEY SOUND SOOOOO DARN GOOD WITH THE REAR SPEAKERS! It was a very noticeable difference in sound quality. I had several people listen as I turned on and off my rear speakers and everyone quickly agreed that the rears made a huge difference. Keep in mind these are the stock rear speakers because my Focal's for the rear will not arrive until today. But Holy Moly...........I'm glad I turned those rear speakers on and tuned them as well as the front speakers! I can only imagined what the system will sound like once I install the Focals in the rear.

I can't thank this website/forum enough for some of the good information that I have acquired over the past 2 weeks!

BTW, I don't have any echoing as reported by some and I didn't have to toggle with the Time Alignment settings for the rear speakers. Not sure if the installation shop previously set all of that up before turning off the speakers from the DSP. And yes my fader works as it should. I must say that the shop did an awesome job with everything.

Sent from my SM-N950U using Tapatalk
 

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Okay! So, I tried doing the l-r/r-l with 50-50% and opposite outputs inverted approach as mentioned here. Muted all other channels, and only kept the rear channel open. I found that this makes music sound as if I'm using a 3" inch mid-range, band-passed from 700hz to 8000hz, and fairly hollow. Is this how it's supposed to sound? On the contrary, if I simply use the opposite inputs (Rightin-Left Out, vice-versa) at 100% without inverted polarity for the rear channel, it sounds much better.

Am I doing something wrong here? Details of my setup as follows:

Helix V Eight DSP.
Focal 165 Coaxials crossed at 80hz HPF till 8000hz LPF. Time-aligned using distance, and running attenuated at -4db.

I have only two inputs available from the source unit.
 

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keep in mind that the purpose of rear fill as described here is to create an ambiance effect or try to recreate a sense of room reflections. Using this technique the only information that comes out of rear fill is information that isn't part of the center of the soundstage, in other words it is part of the recording that you wouldn't hear coming out of the middle of the soundstage. It is going to sound diffuse and hollow because that is what echo or reverberation will sound like.

If you do it the way that you described changing it, the rear speakers will sound better if you are listening to them alone. However, the effect will be that your front soundstage will be pulled towards the back and you will lose focus and detail on the front soundstage.

From a competition standpoint this would be the last thing you would want to do. However, if you like the sound to wrap around you and don't care about the soundstage being accurately created in front of you, then go for it! It is a matter of what you want from the system.
 

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keep in mind that the purpose of rear fill as described here is to create an ambiance effect or try to recreate a sense of room reflections. Using this technique the only information that comes out of rear fill is information that isn't part of the center of the soundstage, in other words it is part of the recording that you wouldn't hear coming out of the middle of the soundstage. It is going to sound diffuse and hollow because that is what echo or reverberation will sound like.



If you do it the way that you described changing it, the rear speakers will sound better if you are listening to them alone. However, the effect will be that your front soundstage will be pulled towards the back and you will lose focus and detail on the front soundstage.



From a competition standpoint this would be the last thing you would want to do. However, if you like the sound to wrap around you and don't care about the soundstage being accurately created in front of you, then go for it! It is a matter of what you want from the system.
Thank you! That was just the answer I was looking for :)

Sent from my BBF100-6 using Tapatalk
 

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Hi Guys quick question,



is this by anymeans possible off a head unit rather than the dsp? I mean consider the head unit can bandpass say for example 300-3000hz 12db slope and has 20ms time aligment,can obviously attenuate also this leaves the L-R/R-L arrangement to be done.

but can this be done physically by the way we wire the speakers? If so can someone help me understand how :) ?


basically I plan to sell my P six and bought a Helix Dsp mini but this is only 2 way front,since I already have a Pioneer DMH-2550Nex head unit I can perhaps use the 2 channels output (front channels) from the headunit into the dsp for full 2way front

and then the 2 channels rear out from the head unit (hi level) bandpassed (network mode) and time aligned to the rear speakers as rear fill but want to know if I can get that L-R/R-L arrangement or how ever its written :)
 

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No way to wire the speakers to get the differential signal that you are looking for and no HU that I am aware of that will do it either. Why selling the P Six if it does what you want? Personally I've been down the road of rear fill in two high end builds. I've ended up doing away with it because I think it smears the image. Also, it sounds terrible for rear seat passengers. When a good SQ system is set up properly there should be plenty of ambient information but YMMV.
 

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No way to wire the speakers to get the differential signal that you are looking for and no HU that I am aware of that will do it either. Why selling the P Six if it does what you want? Personally I've been down the road of rear fill in two high end builds. I've ended up doing away with it because I think it smears the image. Also, it sounds terrible for rear seat passengers. When a good SQ system is set up properly there should be plenty of ambient information but YMMV.

thanks for the reply mate!

to be honest I only need and want 2way front and I'am selling the P six for financial reasons, It goes for around 850-900 dollars here used,I got the helix mini dsp inc hec usb for dirt cheap at roughly 230 usd as a demo unit from a friend who is a dealer.

I also got the sony hi res amps GS4 & GS100 mono for a total 200 usd so for 430 usd I now have a full 3 way setup complete and can keep the extra 420-470 usd for myself.


though I'am worried as I'am getting very very odd user reviews/reports of the GS4 (GS400) amp as some state its crazy good and performs excellent especially for the money while others state it performs no where near a high end amp like the P six both in terms of staging,sq and especially output while the other bunch who stated it was good reported back that this was BS and that it has plenty balls to perform enough unless Iam in search for crazy SPL
 

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You are welcome. Ok, makes sense. Did you run rear fill with the P6 before? I didn't explain in my previous email that the reason you can't do it with wiring is that the L-R signal is only playing the information that is specific to one side and none of the center info. It takes DSP to do that. I've heard competition vehicles with rear fill that I really liked. It sounded pretty cool in my Jeep but with certain music I felt like I got unwanted changes to the imaging. For example, strong ambient info on loud piano passages would pull the image toward me instead of it staying put over the dash. On the other hand, when I had it in my old 911 the rear speakers were so close that it created a bit of a wraparound headphone effect. That was cool driving down the road, but from a competition perspective it would probably cost you points.
 

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you need to bandpass midranges heavily and dont use tweeters on Rear fill + they need to be heavily delayed - 50-60ms. also output level should be very low so they dont pull image to the rear.
 
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