# 2018 Chevy 2500HD Duramax stereo install project



## moregrip1 (Jul 17, 2018)

First and foremost I'd like to thank all those that have posted their stereo builds on these 2015+ GM trucks! It's been a great help!

Second and in all honesty, this will be my first crack at fairly involved stereo install and because of that I'll, no doubt, have plenty of questions as I go along.

Thirdly, I think I've collected just about everything I'll need to get this install completed or well on its way.

Lastly, my idea for this effort is to break the install up into manageable (smaller) jobs as much as I can to keep moving in the right direction and so that I don't get overwhelmed.

As for the gear I've selected; it's all pretty standard stuff for these later model GM trucks; mine has the 8" screen without Bose so I bought the _AmpPro_ _AP4_-_GM61 _and_ JL Twk-88 _for signal processing.

For amplifiers I'll be running two _Pioneer_ units (a 4 channel and a mono)

For system speakers I chose _2x Kicker 10" L7 subs_, a set of _JBL components_ for the front speakers and some _JBL coaxial_ for rear fill.

So that's it in a nutshell....looking forward to spending many hours getting this all figured out and installed!


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## ajt976 (Feb 27, 2019)

Sounds like a good start! I've been really pleased with the AmpPro and my non-Bose setup. The lack of stereo signal for the radio does sound pretty lame to be honest, but I really only tune in for morning radio shows, any music is coming from my phone via Android Auto. It was a compromise I was willing to make in order to have a good signal to start with and the ability to turn down the chime volume (also a single optical cable to the DSP was nice).

Good plan on the smaller manageable chunks. I tried to follow the same approach. Started with power wiring, then AmpPro/harness, then amp rack, so on and so on. It made it a little easier to try and accomplish small tasks, and it also helped to do it in pieces that could be completed and benefits realized immediately.

Best of luck with the build!


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## moregrip1 (Jul 17, 2018)

ajt976 said:


> Sounds like a good start! I've been really pleased with the AmpPro and my non-Bose setup. The lack of stereo signal for the radio does sound pretty lame to be honest, but I really only tune in for morning radio shows, any music is coming from my phone via Android Auto. It was a compromise I was willing to make in order to have a good signal to start with and the ability to turn down the chime volume (also a single optical cable to the DSP was nice).
> 
> Good plan on the smaller manageable chunks. I tried to follow the same approach. Started with power wiring, then AmpPro/harness, then amp rack, so on and so on. It made it a little easier to try and accomplish small tasks, and it also helped to do it in pieces that could be completed and benefits realized immediately.
> 
> Best of luck with the build!


Thank you! I followed your build thread for reference....pics aren't showing up anymore though. Planning on running 1/0 main power through the firewall; the big rubber grommet seems the most common but its fairly covered up in my truck. 

So you ran the toslink? What length did you need and how do you like that vs the rca's?


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## ajt976 (Feb 27, 2019)

moregrip1 said:


> Thank you! I followed your build thread for reference....pics aren't showing up anymore though. Planning on running 1/0 main power through the firewall; the big rubber grommet seems the most common but its fairly covered up in my truck.
> 
> So you ran the toslink? What length did you need and how do you like that vs the rca's?


Yea, for some reason all my Google photos links broke after the forum update, haven't had the time (or motivation) to go and fix them all yet. If you have some specific things you need or want to see, let me know and I can repost them.

Yea, I was able to use that big rubber grommet, however the rubber "flap" piece was definitely a bear to get out. I had to work it for a good 10 minutes or so to get it out. It helped to unbolt that box underneath if you haven't done so already.

Yes! I ran both the optical AND some 6 channel RCA's. Honestly I don't have a fair comparison between them because the RCA's I had running directly into the amp at first whereas the optical swtich was done in conjunction with the DSP of course. I think really the difference I hear is the addition of the DSP to the mix. You will find some that have said the RCAs out of the AP4 can be noisy, though I didn't really notice that while using it directly into the amp. I guess it just comes down to preference, tho if I'm being honest I feel like the optical has the "cool" factor going for it, all digital straight to the DSP!

I ended up going with a 15' optical cable, it gave me enough to run from the AP4/radio under the dash and down the drivers side with about 2' to spare on the back wall where I mounted my amps. It's hard to tell here because it's not quite zoomed out but I think I still have one or two coils of length on that toslink that I tied inside the rear pillar and it reaches the DSP that's almost in line with the seatbelt bolts:


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## moregrip1 (Jul 17, 2018)

I have a small sheet (24" x 48") of 1/4" thick ABS on its way and like you, wanted to utilize the back wall for mounting the amps, DSP, etc. I think I will follow suit and get my power wires run to the back wall first. Any pics and/or tips for that first operation is greatly appreciated!


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## ajt976 (Feb 27, 2019)

Hmm...where to start. The little plastic covers on top of the wire chases in front of the doors were kind of a pain in the butt for me for whatever reason. Also, it was easier for me to pull the wire first and then terminate it once I got the end through those chases. I think I ordered something like 22ft of wire for the main power run but used less than 20ft.

I'm assuming you are using some distribution block(s), so maybe think about where you want to mount those. I kind of made a mistake by not taking into consideration the "features" of the truck when I laid out that rack. The way the main power comes into that combo block it makes it go right across the cab vent on the drivers side. I didn't think much of it until I tried to put the factory sound insulation back and now it won't seal around the vent properly. This causes some road noise that creeps in from that vent, it's slight but noticeable when no music is playing.

The rubber "nipple" in the engine bay that most have used to get inside the vehicle was big enough for me to fit some 1/0 Kolossus Fleks that I sleeved in some PET. Worked great. I can definitely recommend using ferrules, they made life a lot easier (once I finally managed to stuff that oversized 1/0 into one...) when connecting to the distro block.

Have you given any thought to how you will attach that ABS to the back wall? I will say that I do NOT recommend the JB Weld/epoxy and elevator bolt method, could not get it to hold. If you plan on using some nutserts in that channel, be sure to check inside the channel first for any supports that may be hiding, definitely hit one on the drivers side.

I'm sure there is a bunch I'm forgetting, but if you have specific questions I'm happy to share what I learned.


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## moregrip1 (Jul 17, 2018)

ajt976 said:


> Hmm...where to start. The little plastic covers on top of the wire chases in front of the doors were kind of a pain in the butt for me for whatever reason. Also, it was easier for me to pull the wire first and then terminate it once I got the end through those chases. I think I ordered something like 22ft of wire for the main power run but used less than 20ft.
> 
> I'm assuming you are using some distribution block(s), so maybe think about where you want to mount those. I kind of made a mistake by not taking into consideration the "features" of the truck when I laid out that rack. The way the main power comes into that combo block it makes it go right across the cab vent on the drivers side. I didn't think much of it until I tried to put the factory sound insulation back and now it won't seal around the vent properly. This causes some road noise that creeps in from that vent, it's slight but noticeable when no music is playing.
> 
> ...


Did you have to remove the C-Pillar plastic piece to trim the stock sound insulation and route wires?


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## ajt976 (Feb 27, 2019)

moregrip1 said:


> Did you have to remove the C-Pillar plastic piece to trim the stock sound insulation and route wires?


Yes, you kind of need to in order to get the factory sound mat off. There's 3 plastic washer/nut deals on each side that is much easier to access with the pillar off.


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## moregrip1 (Jul 17, 2018)

ajt976 said:


> Yes, you kind of need to in order to get the factory sound mat off. There's 3 plastic washer/nut deals on each side that is much easier to access with the pillar off.


Thanks for taking the time to answer my questions! Greatly appreciate it. I'll check in when I'm a little farther along. I did install a rear seat lift bracket kit to get more room in an attempt to get close to the specified sealed subwoofer volume needed for the two 10" L7's. Not a perfect solution just yet as some adjustments need to be made to make it function better.


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## moregrip1 (Jul 17, 2018)




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## ajt976 (Feb 27, 2019)

I'm interested to see how the LMI kit works for you, I've really been struggling on how to design a better box that will fit in that shallow of a space. Their description was a little hard for me to understand, does it include some latch extenders for the seatbacks? And then are they short enough to "unlock" when the set is raised and allow the seat backs to come forward?

I feel like eventually I may go this route. Outside of the additional height, it'd be really handy to have access to the back wall where the amps are, though once everything is set and dialed in I'm not sure how often that'd happen.


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## moregrip1 (Jul 17, 2018)

The LMI kit is nice in that it provides a fairly clean way of spacing the rear seat up it what appears to be a reasonably safe manner. It is, however, not without a few issues on the newer trucks. 1) the seat folds down just fine but the nut on the seat frame gouges the side decorative plastic trim when doing so. My thought to fix this is just to trim a 1/2" or so off the plastic panel to allow the nut to travel through its full arc without making contact with anything. 2) The rear seat can fold down after the bottom is folded up because the seat back rises when you do this. There are no bracket extenders on the newer trucks because there is enough contact when open (bottom seat down) and the back seat rises enough when the bottom is folded up to allow the seat hook to release from the metal slot on the back wall to fold down. Problem is, where the seat-back metal hook engages the metal slot is so tight the plastic insert that attaches to the inside of the metal slot (so there is no metal to metal contact) dislodges with this movement. My plan is to use some old school (black) weather stripping adhesive in the hopes it locks the plastic pieces in place such that they don't come out with the movement.

If you'd like, I can take pics of what I am describing to give you a better idea of what's going on. At the end of the day, if all works out, the fixes are simple and I really don't know of any kit better than the LMI. I've had the rear seat loaded; no issues.


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## ajt976 (Feb 27, 2019)

Sure, I think I'm tracking so far but a picture always helps.

Good information to know though, I wouldn't have thought about clearance issues between the nuts and plastic panels. And yes, those plastic inserts on the seatback hook "loops" are kind of a pain, I knocked them off several times just taking mine in and out.


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## moregrip1 (Jul 17, 2018)

Here's where the nut makes contact with plastic; just going to trim that portion off....should be mostly unnoticeable


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## ajt976 (Feb 27, 2019)

Yea, that's kind of annoying, totally wouldn't have thought about that tho.


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## moregrip1 (Jul 17, 2018)

ajt976 said:


> Yea, that's kind of annoying, totally wouldn't have thought about that tho.


I believe its the 2014 and older models that don't have that problem/no plastic there; minor inconvenience for the added benefit!


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## moregrip1 (Jul 17, 2018)

MTI acoustics had a 20% off sale so I ordered and full length sub box up-firing to fit under the rear seat for the two kicker L7's. Nothing fancy like most of the boxes I see them make, just simple black carpet so it mostly fades away under some dark window tint. I'll snap a few pics and post them when it shows up!


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## BlitzBlackGSXR (Jun 29, 2012)

Awesome ! This is some good info ! I just picked up a 2016 Z71 LTZ Crew cab Duramax myself. I have a list of stuff to go in it.
Hybrid Audio 
L1v2 Pro tweetera
Unity U3’s mid range for the dash
Unity U69s for the mid bass for the front doors
Unity U61c-2v2 (convertible components) for the rear doors
Zapco ADSP-Z8 IV II (8 ch amp/DSP)
Hybrid Audio Unity U1A amp 
2 JL Audio 13TW5-4’s 
MTI Acoustics sub box
KnuKonceptz 0 gauge power wire with some 4 gauge wire
KnuKonceptz Krystal 4 ch & 2 channel RCA’s 

not sure if I want to run the AmpPro unit or the Nav-TV unit.
I’ll be running everything active thru the DSP. I cant wait to get everything installed. I’ll be sound deadening all the doors too.


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## moregrip1 (Jul 17, 2018)

BlitzBlackGSXR said:


> Awesome ! This is some good info ! I just picked up a 2016 Z71 LTZ Crew cab Duramax myself. I have a list of stuff to go in it.
> Hybrid Audio
> L1v2 Pro tweetera
> Unity U3’s mid range for the dash
> ...


I'm interested to see how the install goes for you, hope you post a build thread so I can follow! Good luck! I will post my updates as I go!


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## BlitzBlackGSXR (Jun 29, 2012)

Thanks ! Yea I’m still acquiring parts at the moment. I have most of what I need. Then it will be a decision between the PAC unit or the NAV-Tv unit. Then, once all parts are acquired ..... it will be finding time to do the install !! That’s the tedious part !


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## moregrip1 (Jul 17, 2018)

Ok, looks like the MTI acoustics subwoofer box is scheduled for a tomorrow delivery; interested to see how it turned out. The garage is prepped and ready to start disassembly next weekend; all other projects are on hold until the system is in. Hoping to wrap up the install in two or three weekends!


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## moregrip1 (Jul 17, 2018)

ajt976 said:


> View attachment 268487


Do you happen to remember what the rough dimensions were on your amp mounting board? Also, any pics of amp to seat clearance? Thank you!


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## BlitzBlackGSXR (Jun 29, 2012)

moregrip1 said:


> Ok, looks like the MTI acoustics subwoofer box is scheduled for a tomorrow delivery; interested to see how it turned out. The garage is prepped and ready to start disassembly next weekend; all other projects are on hold until the system is in. Hoping to wrap up the install in two or three weekends!


That’s awesome !!

my MTI box was delivered last week !! This thing is a work of art !

Stage 2 for 2 JL Audio 13TW5’s , sound deadens/treatment, front acrylic windows and red leds !! This thing is a beast too !!


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## moregrip1 (Jul 17, 2018)

BlitzBlackGSXR said:


> That’s awesome !!
> 
> my MTI box was delivered last week !! This thing is a work of art !
> 
> Stage 2 for 2 JL Audio 13TW5’s , sound deadens/treatment, front acrylic windows and red leds !! This thing is a beast too !!


Your subwoofer box looks fantastic brother! Are you happy with the way it is built? I think you are but I always have to ask. Shipping box intact upon arrival? I tend to be a do-it-yourselfer mainly because I have not had good luck purchasing custom anything! I think I'm cursed or something!

My subwoofer box will not be nearly as nice as yours; I just went with the black carpet; kids and all.


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## moregrip1 (Jul 17, 2018)

Well that was weird and unexpected, sub-box just showed up, on a Sunday no-less:


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## BlitzBlackGSXR (Jun 29, 2012)

moregrip1 said:


> Your subwoofer box looks fantastic brother! Are you happy with the way it is built? I think you are but I always have to ask. Shipping box intact upon arrival? I tend to be a do-it-yourselfer mainly because I have not had good luck purchasing custom anything! I think I'm cursed or something!
> 
> My subwoofer box will not be nearly as nice as yours; I just went with the black carpet; kids and all.


I was a little skeptical at 1st but I was assured I’d be getting TOP quality and man I was not let down at all !! This thing is a work of art ! I wanted to get a little more fancy with it but it gets costly ! Lol 

I’m also a DIY guy but box building is not my forte and this far exceeds my skills !! I’d buy it again if I needed to ! Yea, I was worried that it would show up all beat up but to my surprise it was all intact ! Only issue I had was with FedEx and their stupidity on following instructions !!

But yea, I hear ya on the kids. It’s actually easier to clean the leather than the carpet and my son is 12 and he knows not to mess anything up and he knows I’m clean freak !!

here’s the bottom with the subs in. I haven’t installed yet as this enclosure is expensive as you know, so I’m still gathering my parts.


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## moregrip1 (Jul 17, 2018)

BlitzBlackGSXR said:


> I was a little skeptical at 1st but I was assured I’d be getting TOP quality and man I was not let down at all !! This thing is a work of art ! I wanted to get a little more fancy with it but it gets costly ! Lol
> 
> I’m also a DIY guy but box building is not my forte and this far exceeds my skills !! I’d buy it again if I needed to ! Yea, I was worried that it would show up all beat up but to my surprise it was all intact ! Only issue I had was with FedEx and their stupidity on following instructions !!
> 
> ...


Thanks for the extra detail; very much appreciated!


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## ajt976 (Feb 27, 2019)

moregrip1 said:


> Do you happen to remember what the rough dimensions were on your amp mounting board? Also, any pics of amp to seat clearance? Thank you!


I actually don't have those dimensions written down anywhere surprisingly. I basically measured between the cab vents and subtracted about a 1/4" for some play, if I had to guess it'd be somewhere around 50-52" wide and 13-14" tall.

I did however find a few pictures for you regarding the rear seat clearance:
















These are both with the seat folded up, there is even more space when they are in their normal position. Not sure I could get a decent picture from the top looking at the amps but when I peeked in there just now I'd estimate at least 2" from the top of the amp to the back of the seats. For reference, I used a 3/4" piece of plywood for my rack.

Sidenote, the box looks great! Totally jealous, maybe one day I'll think about that seat lift and go for a monster set of 12"s!


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## moregrip1 (Jul 17, 2018)

ajt976 said:


> I actually don't have those dimensions written down anywhere surprisingly. I basically measured between the cab vents and subtracted about a 1/4" for some play, if I had to guess it'd be somewhere around 50-52" wide and 13-14" tall.
> 
> I did however find a few pictures for you regarding the rear seat clearance:
> View attachment 272081
> ...


More room back there than I expected! Thank you for the pics.

A pair of 12's would decimate all!! 12" subs are my favorite size for subs which is why I always buy 10's; makes perfect sense huh.....lol


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## moregrip1 (Jul 17, 2018)

ajt976 said:


> I actually don't have those dimensions written down anywhere surprisingly. I basically measured between the cab vents and subtracted about a 1/4" for some play, if I had to guess it'd be somewhere around 50-52" wide and 13-14" tall.
> 
> I did however find a few pictures for you regarding the rear seat clearance:
> View attachment 272081
> ...


Another random question, how much of an air gap did you have between the door speakers and door panel grill? Mulling over adding foam rings.....


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## ajt976 (Feb 27, 2019)

moregrip1 said:


> Another random question, how much of an air gap did you have between the door speakers and door panel grill? Mulling over adding foam rings.....


I actually still have quite a bit, enough so that I am contemplating adding another 1" layer to my baffle stack. Either way I think that some CCF around the baffle to seal against the door card is pretty well recommended.


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## moregrip1 (Jul 17, 2018)

ajt976 said:


> I actually still have quite a bit, enough so that I am contemplating adding another 1" layer to my baffle stack. Either way I think that some CCF around the baffle to seal against the door card is pretty well recommended.


What would you say it is, 2" total?


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## ajt976 (Feb 27, 2019)

moregrip1 said:


> What would you say it is, 2" total?


I'd say likely a bit more, tho I wish I had some measurements to back that up. My current stack is 2.5" and I feel like it could be closer to the door card.


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## moregrip1 (Jul 17, 2018)

ajt976 said:


> I'd say likely a bit more, tho I wish I had some measurements to back that up. My current stack is 2.5" and I feel like it could be closer to the door card.


whoa, that seems like quite a bit, I thank you once again!


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## rlme36 (Jun 23, 2020)

Subscribing as I have a 2016 CC that I'll be doing adding some better sound to as well. MTI box looks like a very well made box, thanks for sharing the pics. Wondering has anyone tried using the console area for mounting the amps and dsp? Have either of you guys run new speaker wire and if so how did you deal with the door connector? 

thanks, 
Rob


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## moregrip1 (Jul 17, 2018)

the rears are just under 2 1/4" out from the door:


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## moregrip1 (Jul 17, 2018)

rear seat outer side trim panels trimmed; no more interference when seat is folded down! tin snips with relief cuts, a 3" sanding disc and some finish hand sanding with emery cloth = gtg


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## moregrip1 (Jul 17, 2018)

rear pass door outer door skin templates I made for the stinger roadkill, I'll just flip them over for the drivers rear:


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## moregrip1 (Jul 17, 2018)

inner rear door using patterns:









outer rear door:









speaker baffle or whatever its called:









I didn't do full coverage because I wanted to keep it manageable and somewhat simple....hopefully this makes a difference. Going to do a little work on the door panel and call it good.


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## moregrip1 (Jul 17, 2018)

I measured a 1 cm diameter increase in cone area/rear door speakers:


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## moregrip1 (Jul 17, 2018)

for the rear doors, instead of going with foam rings I'm going to try out these silicon rings. With the coaxial in place on the Scosche speaker adapter the outer edge sits just about flush to the factory foam ring......see pics below:


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## moregrip1 (Jul 17, 2018)

some poly-fill for the subwoofer box per Kicker:


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## moregrip1 (Jul 17, 2018)

driver rear door complete; just need to mount the speakers to the door and install the door panels back in:


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## rlme36 (Jun 23, 2020)

Are you running factory speaker wires or going to run new lines for the doors?


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## moregrip1 (Jul 17, 2018)

rlme36 said:


> Are you running factory speaker wires or going to run new lines for the doors?


100% factory speaker wires except to the dash mounted tweeters


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## moregrip1 (Jul 17, 2018)

test fit for amp mount measurements:


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## moregrip1 (Jul 17, 2018)

rear speakers foam taped, loaded, bolted together with SS 8-32 hardware and ready to go:


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## moregrip1 (Jul 17, 2018)

my puzzle project for the day; where to put the pieces:


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## moregrip1 (Jul 17, 2018)

first idea (borrowed from Five Star Audio):


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## moregrip1 (Jul 17, 2018)

second idea; with the 2.5" seat lift I have more room to mount stuff so I stand a decent chance of taking advantage of the extra room. If all works out, as a bonus, I'll get to keep my mounting panels flat and simple (not that I'm afraid of heating the panel to bend....but I am  only got one to work with). Because of that, this is most likely the route I will go.....assuming all things are possible. 2 pieces total; drivers side gets the amps, passenger side gets the crossovers and DSP......behold:


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## moregrip1 (Jul 17, 2018)

small detail; not sure what these are called but when you have the 2.5" seat lift installed and you engage/disengage the seat from the back wall to either fold down the seat or put it back to the upright position, sometimes these little plastic pieces pop off. So I went old school (in my mind anyway) and used some weatherstrip adhesive (Loctite 37532 Black Weatherstrip Adhesive) in the hopes (fingers crossed) they get locked into place:










I used this technique:


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## rlme36 (Jun 23, 2020)

Was the seat lift necessary for the speakers you choose to use or just the nature of their speaker box?


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## moregrip1 (Jul 17, 2018)

rlme36 said:


> Was the seat lift necessary for the speakers you choose to use or just the nature of their speaker box?


Needed the extra height to fit a standard depth 10" sub; so it was my sub choice that drove the need for the lift kit. I probably should have just went with a shallow sub...lol


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## moregrip1 (Jul 17, 2018)

here's a pic of the seat folded down/great feature:


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## moregrip1 (Jul 17, 2018)

this is why I needed to trim/clearance the side plastic pieces:


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## moregrip1 (Jul 17, 2018)

speaker adapters showed up and starting to prep them for install. First thing was to fill the open end with some liquid electrical tape/insulation:


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## moregrip1 (Jul 17, 2018)

some of the parts to get these adapters ready for install:


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## moregrip1 (Jul 17, 2018)

ajt976 said:


> I'd say likely a bit more, tho I wish I had some measurements to back that up. My current stack is 2.5" and I feel like it could be closer to the door card.


Question; where did you pull your remote turn on signal? Thank you!


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## humandrummachine (May 17, 2010)

Lets see a pic of the mighty Dmax itself!


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## moregrip1 (Jul 17, 2018)

humandrummachine said:


> Lets see a pic of the mighty Dmax itself!


Here she is:


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## humandrummachine (May 17, 2010)

Looks good!!


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## moregrip1 (Jul 17, 2018)

humandrummachine said:


> Looks good!!


thank you, much appreciated.


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## moregrip1 (Jul 17, 2018)

not perfect but good enough for this project, had to wait for supplies to show up:

*







*


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## rlme36 (Jun 23, 2020)

would you mind sharing where you got some of your supplies for the super tidy install bits?


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## moregrip1 (Jul 17, 2018)

rlme36 said:


> would you mind sharing where you got some of your supplies for the super tidy install bits?


I'd be happy too, just scroll down and pick what you need....hasn't steered me wrong yet!



https://www.dandftooldrawer.com/


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## rlme36 (Jun 23, 2020)

Thanks, I recently found their site, good to know it works


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## miguel A (Oct 27, 2009)

Thank you for sharing the link know I know what product are called hopefully I can find them locally. Great work so far!


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## moregrip1 (Jul 17, 2018)

got the rear speakers foam taped and mounted up:











polarity checks out, time to get the door panels back on!










going to add some sound deadening around the door speaker area/ABS plastic speaker mounting bracket


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## moregrip1 (Jul 17, 2018)

Again, not perfect, but good enough for this project. I found this area to be rather difficult to get everything to lay flat-ish...anyway, this is the process I've been using. First I trace a "rough" template on a bisquine type product, then stick it to the Stinger Roadkill, cut it out, then use the cut Stinger Roadkill piece to trace a template on the 1/8" Dynamat Dynaliner. Then I clean the area I want to apply it to with Isopropyl alcohol and then apply the sound products.

Door speaker/Stinger Roadkill 









Door speaker/Dynamat Dynaliner









completed door:


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## moregrip1 (Jul 17, 2018)

rear door panels are back on; overall the rear doors sound very solid...feels like I added a decent amount of mass. I also added tesa tape underneath all the door panel plastic pins before I mounted them back up.....not sure if it will help much but figured why not.


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## moregrip1 (Jul 17, 2018)

first time working with ABS sheet; stuff gets everywhere! Again, far from perfect but good enough for this application


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## BlackJack2/1CAV (Sep 1, 2020)

First off, good looking build! Amp racks in 14-18 GM trucks is always fun lol. If I may make a recommendation based off my own failures.- If you‘re going to lift the rear seat for subs/ additional build items, don’t use the seat bolts for your ground(s). They tend to fail over time. The 3 child seat harness loops each have a larger diameter bolt to frame. I removed each shined up the bolt area surface to bare metal, bent the ends straight, then drilled and tapped the ends so I could add two 4ga grounds to each loop. I then applied dielectric grease to each anchor bolt, after hitting them with a wire brush and re-installed. This gives you 6 very clean, separate grounding sources that handle as much power as you want to push through your amp rack.


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## Old Skewl (May 30, 2011)

Did you finish your build? Like to see how the amp rack turned out. Gathering ideas for a '14 GMC Sierra CC w/sliding rear window


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## moregrip1 (Jul 17, 2018)

BlackJack2/1CAV said:


> First off, good looking build! Amp racks in 14-18 GM trucks is always fun lol. If I may make a recommendation based off my own failures.- If you‘re going to lift the rear seat for subs/ additional build items, don’t use the seat bolts for your ground(s). They tend to fail over time. The 3 child seat harness loops each have a larger diameter bolt to frame. I removed each shined up the bolt area surface to bare metal, bent the ends straight, then drilled and tapped the ends so I could add two 4ga grounds to each loop. I then applied dielectric grease to each anchor bolt, after hitting them with a wire brush and re-installed. This gives you 6 very clean, separate grounding sources that handle as much power as you want to push through your amp rack.


Would you happen to have a quick pic that shows what you're describing? Thanks!


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## moregrip1 (Jul 17, 2018)

Old Skewl said:


> Did you finish your build? Like to see how the amp rack turned out. Gathering ideas for a '14 GMC Sierra CC w/sliding rear window


Holy I need to get my butt in gear! The install has been on the back burner due any and all number of unexpected and crazy things going on, sometimes called life! I plan to get back on this very soon, been driving around too long with stock tunes!


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## JohnnyOhh (Feb 19, 2015)

hey do you like the polarity checker? i have this one too, but it seems to be very touchy/finicky. small differences in distance of the device from the speaker changes the results, so to me,.... it's tough interpret the results.


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## moregrip1 (Jul 17, 2018)

JohnnyOhh said:


> hey do you like the polarity checker? i have this one too, but it seems to be very touchy/finicky. small differences in distance of the device from the speaker changes the results, so to me,.... it's tough interpret the results.


From what I remember it worked well enough. Firstly, I was pretty confident I didn't mess anything up. Secondly, it gave me the confirmation I needed to put the door card (panel) back on.


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## moregrip1 (Jul 17, 2018)

So now that I'm starting to think about my install again and prepping to re-start everything. I've decided to add a 3rd pioneer amplifier (4 channel) and some Audio Frog GS25 full range speakers. This will allow me to go full active and run a 3 way system up front. I think the AF GS25's will fit well with the JBL GTi Components. I'll run the 2.5's in the dash/stock location and the tweeters on the A-pillar. As a bonus, the truck came stock with dual alternators so not expecting any power issues.


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## evo9 (Jul 6, 2005)

moregrip1 said:


>


If you don't mind sharing. Where do you get those silicone rings from?


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## moregrip1 (Jul 17, 2018)

evo9 said:


> If you don't mind sharing. Where do you get those silicone rings from?


Not at all, those are NVX rings.


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## evo9 (Jul 6, 2005)

moregrip1 said:


> Not at all, those are NVX rings.



Thank you!


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## moregrip1 (Jul 17, 2018)

Getting a little ahead of myself but hey that's what we do right! Now that I've decided to go active my starting crossover points will be:

using 24dB/oct Linkwitz Riley 

60Hz low pass on the sub.
80-300Hz on the 6”
300-3.5k on the 2.5”
3.5k and up on the tweeter


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## moregrip1 (Jul 17, 2018)

I was just looking through this thread (been a while) and I realized I never posted a pic of the revised subwoofer box. The old box left me no room for subwoofer travel. MTI was good enough to make a new one that will work awesomely (great company!), enjoy!:


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## clange2485 (Dec 10, 2020)

moregrip1 said:


> Here she is:


Great looking truck and build log so far!! Here’s mine you don’t see a whole lot in our color, or maybe yours is a shade different. It all depends on the light.


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## moregrip1 (Jul 17, 2018)

clange2485 said:


> Great looking truck and build log so far!! Here’s mine you don’t see a whole lot in our color, or maybe yours is a shade different. It all depends on the light.


Your truck looks great! When I bought my truck in 2018 they called it Graphite Metallic, they have since changed the name to Gasoline Metallic. So far I've been pretty happy with it!


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## moregrip1 (Jul 17, 2018)

This is what convinced me to do a active 3 way system; from Audio Frog:

"To make installing and tuning the system even easier, we could consider a 3way speaker system in the front. If we add a 2.5” speaker to cover the gap between the woofer and the tweeter, we fix a bunch of problems. We can cross between the 6” speaker and the smaller midrange below 500 Hz. Now, we don’t have to aim the midbass driver at all. We can continue to keep our tweeter happy at 5 kHz (and be between yellow and orange). If we find a tweeter we can cross at 2.5 kHz, then we’re in the green and we don’t have to aim the midrange either. The offaxis sound will contain the same frequency content as the direct sound, and we’ve avoided most of the problem highlighted above. A properly designed 3way system is often much easier to tune than a 2way system."


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## clange2485 (Dec 10, 2020)

moregrip1 said:


> Your truck looks great! When I bought my truck in 2018 they called it Graphite Metallic, they have since changed the name to Gasoline Metallic. So far I've been pretty happy with it!


Thanks I’ve had a couple minor issues but nothing major. Mine is a 17 also Graphite. I’m also doing frog gb 3 ways up front and gs62’s in the rear doors with an mti box.


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## moregrip1 (Jul 17, 2018)

Any good tutorials on flush mounting tweeters? I'm in a bit of a pickle with mounting options for the jbl gti tweeters.....


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## clange2485 (Dec 10, 2020)

Seen this on Facebook awhile back not flush but definitely less restrictive. Kinda cool idea. My tweeters are in the A pillars. I know @SNCTMPL has them in the sails at the moment maybe he can help out.


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## moregrip1 (Jul 17, 2018)

clange2485 said:


> Seen this on Facebook awhile back not flush but definitely less restrictive. Kinda cool idea. My tweeters are in the A pillars. I know @SNCTMPL has them in the sails at the moment maybe he can help out.
> View attachment 312972
> View attachment 312973
> View attachment 312974


Thank you! I was wondering about the room available in the dash area/under the stock grills. I may try to flush mount them on either side of each grill.


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## moregrip1 (Jul 17, 2018)

Got the passenger drivers door completed:


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## moregrip1 (Jul 17, 2018)

drivers side driver prepped:


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## DaveG (Jul 24, 2019)

Very nicely done but why didn't you block off those big holes. That's what needs to truly be done to benefit from your efforts.


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## moregrip1 (Jul 17, 2018)

DaveG said:


> Very nicely done but why didn't you block off those big holes. That's what needs to truly be done to benefit from your efforts.


Thank you. I reinstalled the factory weather barrier. I thought about doing more but decided to leave it at this level.


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## clange2485 (Dec 10, 2020)

moregrip1 said:


> Thank you. I reinstalled the factory weather barrier. I thought about doing more but decided to leave it at this level.


Looks great but like DaveG said you really should block off those openings. I blocked mine off with the bose speakers still installed and it made a huge improvement. Definitely worth the effort!!

I used i wanna say 1/8” abs and heated up the peanut template shaped area with a torch and molded it around the window motor and curves. Added cld to the back and wrapped with edges with butyl rope.


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## clange2485 (Dec 10, 2020)




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## moregrip1 (Jul 17, 2018)

Thanks gents! Stellar work!


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## moregrip1 (Jul 17, 2018)

got the amp rack boards fitted and figured out-ish.....next is the layout....hope I don't mess it up!


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## moregrip1 (Jul 17, 2018)

Hello Murphy! ok, here's my dilemma.....I have eight channels of output from the DSP that will run my 3 way up front and rear subwoofer. That leaves the rear-fill/rear door speakers for consideration. After reading numerous threads/info on rear fill the solution I've come up with, using components I already own, is to run the rear door/speaker level inputs to a LC2i then high pass them in the 300-500hz range at the amp, then run the speaker outputs through the 2 way passive x-overs (woofer output only) to a 4ohm resistor and finally to the actual rear door speakers.

My thought process is: Because the rear door speakers run at 2.5ohms they will get more power than the rest of the speakers running at 4ohms. By adding 4ohm resistors that will get me up around 6.5 ohms with less power delivered to them; I understand this to be desirable for rear fill applications. Additionally, the 300-500hz high pass on the amplifier coupled with the 2500mhz low pass on the passive x-over keeps the higher frequencies at bay that might otherwise negatively affect the front stage.

The only thing I won't be able to reasonably do is delay the rear door speakers the recommended 20-30msec-ish to ensure the front stage is the least affected. But I think I'll be in the ballpark regardless.

Thoughts?


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## SNCTMPL (Nov 23, 2014)

Are they currently still powered by the Bose amp?
If so I would just leave them and fade them almost completely out.


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## DaveG (Jul 24, 2019)

What dsp? Differential rear fill can be run using only one channel but you need to be able to configure the channel with L-R. Does your dsp allow this? If it’s a Helix it’ll work.


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## clange2485 (Dec 10, 2020)

moregrip1 said:


> Hello Murphy! ok, here's my dilemma.....I have eight channels of output from the DSP that will run my 3 way up front and rear subwoofer. That leaves the rear-fill/rear door speakers for consideration. After reading numerous threads/info on rear fill the solution I've come up with, using components I already own, is to run the rear door/speaker level inputs to a LC2i then high pass them in the 300-500hz range at the amp, then run the speaker outputs through the 2 way passive x-overs (woofer output only) to a 4ohm resistor and finally to the actual rear door speakers.
> 
> My thought process is: Because the rear door speakers run at 2.5ohms they will get more power than the rest of the speakers running at 4ohms. By adding 4ohm resistors that will get me up around 6.5 ohms with less power delivered to them; I understand this to be desirable for rear fill applications. Additionally, the 300-500hz high pass on the amplifier coupled with the 2500mhz low pass on the passive x-over keeps the higher frequencies at bay that might otherwise negatively affect the front stage.
> 
> ...


I like both snctmpl’s or DaveG’s options a whole lot better.


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## moregrip1 (Jul 17, 2018)

DaveG said:


> What dsp? Differential rear fill can be run using only one channel but you need to be able to configure the channel with L-R. Does your dsp allow this? If it’s a Helix it’ll work.


I have the twk88....not sure about the differential rear fill. Does that help?


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## moregrip1 (Jul 17, 2018)

SNCTMPL said:


> Are they currently still powered by the Bose amp?
> If so I would just leave them and fade them almost completely out.


I have a non Bose system


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## DaveG (Jul 24, 2019)

moregrip1 said:


> I have the twk88....not sure about the differential rear fill. Does that help?


Not familiar with the twk88. For anyone familiar with the twk88, can it do differential rear fill?

Running the rears off oem will leave you with an echo without t/a.


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## clange2485 (Dec 10, 2020)

DaveG said:


> Not familiar with the twk88. For anyone familiar with the twk88, can it do differential rear fill?
> 
> Running the rears off oem will leave you with an echo without t/a.


Not sure about the twk but im pretty sure chris kept his stock rears and added a 2nd set of rears to C pillars. I’m sure he can explain it better. Are you limited to only 1 tune with the twk or is there a way to switch between them?


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## moregrip1 (Jul 17, 2018)

clange2485 said:


> Not sure about the twk but im pretty sure chris kept his stock rears and added a 2nd set of rears to C pillars. I’m sure he can explain it better. Are you limited to only 1 tune with the twk or is there a way to switch between them?


Does rear subwoofer only need 1 channel?


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## moregrip1 (Jul 17, 2018)

DaveG said:


> Not familiar with the twk88. For anyone familiar with the twk88, can it do differential rear fill?
> 
> Running the rears off oem will leave you with an echo without t/a.


maybe it does:









To rear fill or not to rear fill?


Yeah the audiocontrol processor can't do left minus right. Hell, it doesn't even do left/right eq :( Sent from my VS988 using Tapatalk can I not wire the rear mids together at the amp to create L-R?




www.diymobileaudio.com





either way, I've got a lot to learn here!


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## DaveG (Jul 24, 2019)

moregrip1 said:


> maybe it does:
> 
> 
> 
> ...



It wont. No rear fill for you! Copy and past from Nick and he's a very trusted source:


[IMG alt="SkizeR"]https://www.diymobileaudio.com/d2/avatars/m/47/47471.jpg?1631388440[/IMG]
*SkizeR
Registered*
Joined Apr 19, 2011
19,527 Posts
#20 · Feb 23, 2017

well, i guess i'll do my best to remember what i said and repost it.

to anyone saying not to bother with rear fill, i highly suggest trying to find someone with a PROPER rear fill setup and taking a listen. little do many know, that some of the top scoring cars also use rear fill. it absolutely does not interfere with stereo imaging and also helps enlarge the soundstage if done right. that said, the twk isnt capable of doing proper rear fill


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## moregrip1 (Jul 17, 2018)

DaveG said:


> It wont. No rear fill for you! Copy and past from Nick and he's a very trusted source:
> 
> 
> [IMG alt="SkizeR"]https://www.diymobileaudio.com/d2/avatars/m/47/47471.jpg?1631388440[/IMG]
> ...


Thanks Dave, later on in that same thread someone had said they figured out how to do the differential rear fill with the twk88. I'll try ending JL a message and see what they say. Thanks for the help, I thought I had my bases covered, looks like that may not be so true.


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## moregrip1 (Jul 17, 2018)

Ok message to JL sent; I'm on a 72hour tether!


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## moregrip1 (Jul 17, 2018)

just came across this, so maybe yes?

8 ch DSP for rear fill? | DiyMobileAudio.com Car Stereo Forum


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## Serieus (May 27, 2011)

Manville from JL posted instructions for rear fill here in the VXi thread (mixing should be the same, I don't recall if the TwK can delay the same amount as the VXi amps or not):








JL VXi amps


I'm almost certain that you cannot do "proper" rear fill with those amps. Differential rear fill requires an L-R signal, a bandpass crossover, heavy attenuation, and lots of delay. I'm not 100%, but I don't think the software can do the L-R part, and I'm not sure you have enough delay to work...




www.diymobileaudio.com


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## moregrip1 (Jul 17, 2018)

I heard back from JL, looks like it's possible:

"you can do as you stated as long as you do not mind your rear fill playing in mono. You would just sum left and right signal through a common EQ and then out of one channel of the TwK and then use a Y splitter to feed both rear channels. Then you would repeat this to another output of the TwK and use a Y splitter to feed both inputs of your subwoofer amplifier."

Anyone have any ideas on where/how I would sum the left right signals? Would that happen in the Twk or some other way?

Thanks!


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## moregrip1 (Jul 17, 2018)

Ok gents, I know for a fact rear fill will work (in mono) with the TwK88. JL sent me a screen shot on what it would look like. If anyone is interested I can post up the pic later!


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## nyquistrate (Apr 17, 2011)

moregrip1 said:


> Ok gents, I know for a fact rear fill will work (in mono) with the TwK88. JL sent me a screen shot on what it would look like. If anyone is interested I can post up the pic later!


As L-R?


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## DaveG (Jul 24, 2019)

Can you get a L-R signal or not? Otherwise you can’t get differential rear fill. And running a mono rear is not going to play well with your front stage.


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## moregrip1 (Jul 17, 2018)

DaveG said:


> Can you get a L-R signal or not? Otherwise you can’t get differential rear fill. And running a mono rear is not going to play well with your front stage.


Per JL, the Twk88 can do mono rear fill and mono subwoofer running 3 way up front:


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## moregrip1 (Jul 17, 2018)

So now that I know what the TwK can and can't do for my particular setup I think the new plan going forward is:

1) EQ the mono rear fill in the tuning software.
2) Bandpass the speakers for ~ 300hz to 3000hz. I can play with those numbers in both directions; as low as 100hz-200hz and as high as 5khz to 8khz, whichever sounds best. I'll try to stay away from bass and treble frequencies that might otherwise localize the sound but again defer to whatever sounds best to me.
3) Time Alignement. I will time align starting at 20ms +/- for the rear speakers and adjust as needed.
4) Attenuate the volume level so as not to compete with the front stage (same idea as the mid bass and treble frequencies).
5) If I can't get it to sound good or better than good I can always take them out of the equation.

From this discussion and the many posts I've read, differential rear fill seems to be a more desirable solution and very likely yields better results. With that said, I'm going to go with what I got and see how it turns out. In all honesty this whole system is a bunch of compromises starting with using the PAC GM61 from the factory head unit on back. And from my understanding, the factory (non bose) stereo signals aren't always processed in stereo anyway......"but" I think I can get something that sounds good in spite of the compromises.

I never intended this to be an all out build as you can tell by the components I selected and if I'm being honest, I don't posses the knowledge/understanding to build/install/tune something like that anyway. The only things I selected that might be considered higher tier pieces are the front speakers. Everything else was meant to be in the "budget-ish" realm.

Please let me know what you think of my revised plan! Again, thanks for the discussion and help!


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