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2020 LT Trailboss Bose System audio upgrade

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On 8/24/2020 at 9:21 AM, blyent said:

I have the 2020 High Country with Bose system.  This is what I've done.


My initial plan was just to add a subwoofer.  So I bought a T-harness from LLJ Customs.  I had a local box builder build me a sealed box for a single sub 12" sub.  I had him wrap it in black vinyl to match the black leather seats.  I put in a JL Audio 12w3 in the box.  I powered the sub with a Rockford Fosgate Prime R500XD1 mono amp.  I paid $100 for the box, $150 for the sub (used), and $148 for the amp on Amazon.


I wired it up and it was everything I wanted for bass.  However, there are absolutely no tweets in the factory system.  Their is a 2.75" midrange in the dash and 6x9 mid bass speakers in the front doors.  The sound is very underwhelming.


So, I set out to upgrade the front speakers.  I have some old Boston Acoustics Pro series 3 way compenent speakers (6.5" mid bass, 4.5" mid range, ~1.5" tweeter).  These speakers I've had a long time and they sound amazing.  Anyway the 4.5" wouldn't fit in the dash without some major modifications so I bought some kenwoods off of crutchfield that would fit and thought I'd just use that one instead of the 4.5" mid range from the boston set.  I bought an Audio Control D-4.800 4 channel amp with dsp integrated to power the new speakers.  I thought I could purchase the 6 channel T harness from LLJ Customs for this for about $50.  However, after researching this, the T harness is not what I needed.  I would need the Loop back harness that costs roughly $300. 


In continuing with the research I found that alot of people had issues with the door chimes being super loud after adding an amp and replacing the front speakers.  I didn't want that.  So, I started playing around with the system.


I put a pair of coaxial speakers in the door powered by the bose amp.  That was god awful.  Apparently the only signal it sends to the door speakers in mid bass.  Nothing else came out of the coaxial speakers.  So then I used a posi tap connector to grab the signal from the dash speakers.  Out of the coaxial speakers came nothing but tweeters.  So I knew I could get tweeter and mid range from the dash speakers.  I then took the tweeters from the boston seperates and hooked them up to the posi taps ( not directly though, I still had the signal going through the passive crossover that came with the bostons).  If your able to follow I've got the factory 6x9's in the front door, I've got kenwood 2.75" mid range in the dash,  and I've got boston tweeters tapped into the line going to the kenwoods.


It actually sounded really good.  Not as good as if the full set of Bostons were  powered by an aftermarket amp but surprisingly good.


After hearing all of the issues with loud door chimes and also the navtv unit.  I'm not sure its worth the effort of going with an aftermarket amp for the the front speakers.  I'd definetely recommend trying out what I did on your truck and seeing if you like that.  The LLJ Customs 2 channel T harness for $35 plus shipping is what I ordered.  I didn't add an LOC or anything just used the high level input to the amp.


For cost comparison this is what I spent.


Custom box for 12" sub - $100

JL Audio 12w3 used - $150

Rockford Fosgate Prime 500w mono amp - $148

Kenwood Excelon KFC-X2C 2.75" dash speakers - $70

Amp Wiring Kit off Amazon - $35

posi taps from Amazon - $7

speaker wire from walmart - $13

I already had the Boston Tweeters and passive crossover.








Careful with those boston crossovers being mounted on the sub box I had an old school set of the Boston pro 6.4.3's and had to resolder xover components that snapped off due to vibration.....was also running 3 12's at the time 


Also what sub box is that? looking for something small for a sundown SD4-12


and last but not least Metra recently came out with an axxis factory integration module that is supposed to control the amplified chime issue amongst other issues. 

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Completed a full system upgrade on 2019 Sierra....NON Bose to start, 8" IOS....Began with 140 liner feet of  DynaMat...outside door skins, and inside skins as well....do it all if you are serious about the upgrade, complete floor board coverage to keep the cabin "solid/dead"  Swapped all four doors with the JBL components...JL Audio 10" subs in a SubThump box, JL Audio 5 channel amp and the JL Audio LC7 controller.....JJL Audio takes awhile for their loop harness before shipping (a month!)....it is awesome...once you get it!


Long and short of it...Sounds awesome....more than I really expected


Weird drawback....Never considered the warning bells for rear seat child guard, seat belt warning, phone interface, etc....ALL OF THIS IS SCREAMING AT ME!


Is there anyway to either mute or disable these warnings/chimes to not BLAST through the new audio sound?


The sound is great...just want to reduce the blast from the left front on the additional signal these speakers receive.....


Headed to the dealer today to do the NAV upgrade (flash)....Hoping they understand the tech part....


PS....DynaMat really helps deaden the sound the onboard compressor makes under the rear seat compartment keeping the 3 gallon air tank full for the Ride Rite air bags and train horn!!!!


Now I need a new project to add to this ride!

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