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Discussion Starter · #1 ·
Been taking bites at this build for a while now, thought I might share it in case it helps other stinger owners, and and see if anyone has any comments/suggestions/advice.

The car: 2019 KIA Stinger GT2.
This is my daily driver and I've already put 50K on her. The HK system is pretty good for an OEM system, but I spend so much time behind the wheel I really want to
a) reduce road noise, and
b) improve the stereo system.

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The plan:
  • Sound treatment
  • replace drivers
  • add a real subwoofer
  • fully active DSP

Phase 1: sound treatment

I started with the trunk, there's nearly zero OEM sound deadening material back there, and with my MBRP exhaust it's pretty drone-y back there.
CLD on all the flat sheetmetal, followed by 1/64" lead sheet covered by 3mil plastic sheeting and 2mm flooring underlayment (don't judge).

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Next I attacked the wheelwell liners. I used Thermozyte (synthetic jute with a foil radiant barrier) followed by 1/16" MLV.
I also lined the inner wheelwell liners in 1/16 MLV.

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Now the doors. Used Dynamat xtreme on the outer skins and 1/16 MLV behind the door card. I used 1/16 as a compromise between performance and weight. This is a sporty car after all, and I'm willing to sacrifice a few DBs to continue beating up on Chargers/Camaros/Mustangs.

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Lastly the floor.
The stinger floor is so busy I had a hard time getting good coverage and as such, there wasn't really any noticeable reduction in noise. Given the chance I would not do this again.
Pic is WIP, I apparently didn't take one of the finished product.

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Results:
Soundproofing is a touchy subject, and notoriously hard to measure, but I tried to get at least SOME objective evidence. Measurements taken with REW and UMIK-1.
NOTE: these recordings were taken on the same road under similar driving conditions, but they were weeks apart and other factors could surely add to error (plus 75 is a busy road and it's a ***** to get a measurement on the same strip of road with no adjacent cars).
First, the noise at idle is definitely, and noticeably, lower.

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At speed however, it's harder to tell.
Subjectively I feel like road noise is less fatiguing, but not necessarily lower in volume. This is probably due to the higher frequencies being substantially lower, but under 2K there's pretty much no difference.
The door treatment completely eliminated noise from adjacent vehicles, so it's definitely worth it just for that.

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(I have more pics, but apparently there's a max of 10 per post...)
 

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Discussion Starter · #2 · (Edited)
OK, time for the audio mods.

I'm budget limited, but I think this will strike a good balance between SQ and wallet....for now.

The plan:
  • Front Doors: Audiofrog GS10, GS25, stock midbass
  • Rear Doors: stock (midbass, midrange, tweeter)
  • Center: Audiofrog GB40, GB10
  • Sub: Audiofrog GB10D4
  • Amp: Helix V12, Toro MR2

First up, Tweeters.
I decided to do sails because I'm too cheap to buy new A-pillars ($100ea), this turned out to be more difficult than I thought.

First I modeled up the pods in Solidworks. I have a small graveyard of PLA templates I made to get the angles and drafts right, but after about 8 "vase mode" templates I got something that fits perfect.

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template model, I was able to smooth out that horizontal ridge on the fwd side.

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Printed in PETG and wrapped in alcantara. I really suck at upholstery so there's a few seams if you look closely, but the black hides it pretty well. Maybe once I get my voron built I'll re-print in ABS and get it professionally upholstered.

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These are a compression fit for the GS10/GB10, and have a notch in the pocket for the wires and a center hole for pushing the tweeter out.
On the back is a counterbored pocket that I JB-welded a 3/4" neo magnet into. The mating magnet is screwed into the plastic sail trim (CSK magnet). It holds very well.

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The stock HK system has 3 speakers in the doors, but the 2.5" midrange and tweeter run on the same channel. There is no crossover, only a small capacitor on the tweeter.

I want these frogs to be fully active, so I needed to run an additional wire into the door. This proved to be a much bigger PITA than I expected. KIA uses a bulkhead connector on the door wiring. I do not have the tools to piggyback into this connector, nor do I want to disassemble the dash to get to the inboard side of the thing, so it's onto plan B.


OFF WITH THE DOORS!

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I'll be using this little grommet below the main connector. I was able to fish a wire to another hole in the body (where I also added a grommet).

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Applied shrink wrap and snuck it into the OEM door grommet, doesn't look too out of place.

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Here's a link to the STL for the pod in case another stinger owner wants to print it:
KIA Stinger Tweeter Pod by Aarvix
 

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Nicely done!! My wife has a 2017 optima with the HK system and I was impressed by the clarity, but definitely lacks some bass. I'll inherit her car and upgrade it when we get her an SUV in the future. Can't wait to see your finished product!
 

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I'm willing to sacrifice a few DBs to continue beating up on Chargers/Camaros/Mustangs.
Hey, I take offence to this lol. I have a 2018 GT Limited, which is the CAD version of the GT2, and a 2021 Camaro 2SS and as fast as the Stinger is, I still think my Camaro will take it :)
Amazing build log! Following for sure.

I may have missed this, but how are you integrating the V12 into the HU? I couldn't find any OEM integration devices for this car
Also, what about the underseat subs? I have a 3-way set of Morels for the front stage already (Hybrid 63) but don't know what to use for subs that would fit in the OEM underseat locations...
 

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Discussion Starter · #6 ·
A stock stinger wouldn't stand a chance but with a JB4 and E30 it's pretty evenly matched. Too bad you're not in TX so have a friendly trip to Mexico to find out :)

I looked for an integration solution and wasn't having much luck (turns out Mosconi may make something, but I already had the Helix at that point)

I'm just going high level since I refuse to give up OEM HU and steering wheel volume control.
The Helix V12 has twelve high level inputs, and the OEM amp has eleven outputs. I'll sum channels and EQ as needed, hopefully there aren't too many all-pass filters to muck things up.

I will not be using the underseat subs.
They're a non-standard size, around 7", so you're stuck with them. They do wake up quite a bit if you give them a dedicated amp. Jeff Hulbert has a great video on Youtube going over this.
 

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looks great !! i definitely would love a set of those pods !! pm me for details
 

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Discussion Starter · #8 ·
Center channel time.

The stock system uses a single 4" center channel speaker, but interestingly the dash is provisioned for a second speaker on the passenger side. I can only assume base audio system uses it instead of the LH side.

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This opens the possibility of installing both a midrange and tweeter in the center dash, there's only one problem: the OEM grille only has holes for the driver side.

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Time for some ultra-tedious drilling!

I found a bit slightly smaller than the molded holes and went to work. After drilling I deburred the back side of the holes, then hit the whole thing with a quick pass with the MAPP gas torch to smooth out the drill marks a burrs. Be very careful here, the grille WILL begin to warp, just press it against a flat surface until it cools and viola!

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Back to Solidworks for some more 3D printed adapters.
GB40 adapter goes on the driver side, GB10 adapter on the passenger side. No drilling/cutting required, but I did fill the gaps with a little PSA-backed CCF and dynamat (no pic).

I also uploaded these to Thingiverse:
KIA Stinger Center Channel Speaker Adapters by Aarvix

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The tweeters come with some slick mounting gadgets. I chose to use the backing plate with the spring to secure the GB10. Unfortunately it's not a very strong spring and makes.....spring noises....I guess.
Wrapped it with a little dynamat and no more noise.

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Discussion Starter · #9 ·
Time for some junk in the trunk.
This is my first time building a fiberglass box, so please don't be too harsh. I think it turned out OK, but some of the contours don't match perfectly, and there's a few gaps that shouldn't be there.
I attribute this mostly to me glassing the interior panel out of the car, where it probably deflected a bit and I didn't notice.

Audiofrog GD10D4, she's a beefy girl, Diet Coke for Scale.

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Planning to put this in the hatch behind the driver side wheelwell in an effort to conserve as much cargo space as possible.

Took some rough measurements and I'm a bit shy on airspace (needs .6 ft^3), but I managed to relocate the power hatch module to make a bit more space (the black box on the aluminum bracket used to be much higher). It turned out to be exactly the .1 ft I needed, lucky me!

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Taped up the panel and created a little "doghouse" that extends into the newly-created space.

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First layer of glass.

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Many more layers later. Made some MDF rings then fleeced and glassed the inboard face.
I also filled it with water to check for leaks and measure volume. Came out just over .7 cubic foot, which matches the AF suggested box size.

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Check fit after the first pass of glass filler and sanding.

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Finished product after more filler, lots of sanding, and carpet.

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Needs a grille for that sub, any suggestions for one that will fit an AF GB10D4?
 

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Time for some junk in the trunk.
This is my first time building a fiberglass box, so please don't be too harsh. I think it turned out OK, but some of the contours don't match perfectly, and there's a few gaps that shouldn't be there.
I attribute this mostly to me glassing the interior panel out of the car, where it probably deflected a bit and I didn't notice.

Audiofrog GD10D4, she's a beefy girl, Diet Coke for Scale.

View attachment 306933


Planning to put this in the hatch behind the driver side wheelwell in an effort to conserve as much cargo space as possible.

Took some rough measurements and I'm a bit shy on airspace (needs .6 ft^3), but I managed to relocate the power hatch module to make a bit more space (the black box on the aluminum bracket used to be much higher). It turned out to be exactly the .1 ft I needed, lucky me!

View attachment 306934


Taped up the panel and created a little "doghouse" that extends into the newly-created space.

View attachment 306935





First layer of glass.

View attachment 306936


Many more layers later. Made some MDF rings then fleeced and glassed the inboard face.
I also filled it with water to check for leaks and measure volume. Came out just over .7 cubic foot, which matches the AF suggested box size.

View attachment 306938


Check fit after the first pass of glass filler and sanding.

View attachment 306939


Finished product after more filler, lots of sanding, and carpet.

View attachment 306940


Needs a grille for that sub, any suggestions for one that will fit an AF GB10D4?
i have one for ya !
 

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Couple fiberglass tips. Use a wax on top of the tape for an easy release. You can also use tin foil/spray adhesive on top of the blue tape instead. Tho wax is easier.

When you lay the glass. You don't want to do more than like 4 -5 layers at a time. You'll want around 8 layers for a sub enclosure.

If you do a few layers at a time. Always finish each session with a fiberglass cloth as the last layer. It dries with a smooth finish which means you can lay more mat on top without have the air bubbles caused by an uneven surface that the mat leaves. It also means zero tiny needles sticking you later too

Also finish your last layer with cloth. Its SO SO much easier to sand smooth and you'll barely use any body filler.

Also you'll want to make sure your original mold is completely dry before you pull it. From my experience. If its still a little sticky or bendy. You can pull it too hard and cause it to warp.

...also dont use fleece. It SOAKS up the resin and adds zero strength. Resin isn't strong. Resin in mat is. Use the stetchiest thinnest material you got. Like panty hose thin. Lay resin. Itll wet out super easy. Let it dry and then start adding mat on top.





Sent from my XT1710-02 using Tapatalk
 

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OOOOOOooooh!!!! This is some serious inspiration! I'm thinking about doing something very similar in my GT1. I can't tell from the photos-did you remove the factory carpet on the driver's side before beginning?
 

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Discussion Starter · #13 ·
Thanks for the tips @Jscoyne2 !

@mfenske I did not remove any factory carpet, I just taped over it and then put some Johnson's paste wax on the tape as a mold release.
Most of it came off without hassle, but there's a few bits forever bedded in the resin.

The factory cover is modified though, because of the little outboard extension I created. If you remove the box you'll be staring at the cabin vent and power hatch module.

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I did have to trim the little carpet flap on the spare tire cover since it normally extends into the area that is now occupied by the box.
 

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Discussion Starter · #14 ·
Got the Helix all mounted and powered up.

The wiring behind the hatch liner is still a bit of a trainwreck. It's all hardwired at the moment, but I plan to redo the wiring with some kind of quick-releases (deutsch connectors or cannon plugs most likely).

11 inputs, 12 outputs.....sooo many wires. Everything will get soldered, heat shrunk, and sleeved with expanding wire braid.

WIP pic:
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fabbed up and carpeted a little panel for the Helix.

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Installed.
It sits completely outboard of the wheelwell, so no real loss of cargo space.

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I'll probably print a replacement grille for the wire pass-throughs that can utilize some kind of circular or MS21266 caterpillar grommet to limit chafing. Also may install a permanent hidden USB cable for the helix, but this will do for now.

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I guess it's time to learn how to tune this thing now...

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Discussion Starter · #15 ·
Starting to re-think my plan to use high-level inputs off the stock amp.

Below are input RTA plots from the Helix.
Mids and highs seem to be manageable and I've gotten them pretty flat.
My biggest issue is the door woofers. They sound like absolute crap, hollow and muddy and I'm certain they're reaching their excursion limits at higher volumes.

I've tried summing the sub and door woofer channels to try and play my sub a bit higher, and things just sound even worse (likely phase and timing issues I don't know how to fix). So now I'm looking for a suitable replacement 6.5-7" woofer for my doors.

Door mid/high RTA
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Door low RTA:
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Sub RTA:
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Center RTA:
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its so easy to get a nice flat signal with the spdif input from the oem head , you just need a director for the volume control everything else works as it should
 

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Discussion Starter · #17 ·
Where are you mounting the director?

The GT2 doesn't have any unused switch plates.
 
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