New Audio Build - 2020 Rubicon

Mattk11

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'20 JLU Rubicon
Inspired by DavidRam's build I decided to post my own. If you ever saw my previous build in my JK, you will see a lot of similarities and a few changes. I'm really glad the new Jeeps have the large touch screen that can be connected via optical, it will make things much cleaner and more integrated this time around.

Following the theme:

Budget:
Unknown, I'll figure that out when I get there. This won't be a audiophile high end build, but will be middle of the road with the goal being clean clear audio and bass present when the top it off and on the interstate. This will be an active three way system for the front and two 10" subs under the front seats.

Components:
Signal - Factory 8.4" head unit with PAC Audio unit
Amps - Arc Audio KS 125.4 (70wpc into 4ohms for 2 tweeters and 2 midrange); Arc Audio KS125.2 BX2 (~100-110 wpc into 3 ohms for the Mid-Woofers); Sundown Audio SFB-1500 (1200w into 2ohms; 1750w into 1.3 ohms - more on that later)
Processor - JL Audio TwK D8
Speakers - Tweeters - 1" Scanspeak D3004/60200; 3" Midrange - CDT Chrome ES-CRM-3K; 6.7" Mid-Woofer - CDT Chrome ES-CRM-6K
Subwoofer - Sundown SD4-D2 x2. adding third - more on that later

Connections:
KnuKonceptz Krystal Kable RCAs
KnuKonceptz Karma speaker wire
KnuKonceptz power wire

Sound Deadening:
Noico mat
Noico closed cell foam

Fabrication:
Fiberglass Under-seat Subwoofer enclosures - have to account for floor vents under the seats
Fiberglass Tweeter Pods
Speaker pods - added Scanspeak aperiodic vents (used these in my JK, but not sure if they really help of not)
Amp rack from PVC for waterproofing
Fiberglass Cargo cover with integrated 3rd Sub for summer top-off driving


Amps.jpg
Sundown Amp.jpg
JL TwK.jpg
Speakers.jpg
Sub.jpg
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Mattk11

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My Son has spent the past few years fabricating and selling custom fiberglass subwoofer enclosures that fit under the front seats of the Wrangler JKU. These enclosures were .6 cu ft, solid fiberglass and sprayed with Line-X. Unfortunately, the JKU enclosures don’t fit in the JLU, that means we have to do some new fabrication.

1st issue is that the new JLUs have a vent under the front seats, we decided to re-route those vents so the Sub would have more clearance. It took some trimming of the original vents, and we had to fabricate a new path for them to vent out the back. (The X is where the subwoofer's new NEO magnet will sit. It's the lowest point of the seat pan -we did the same on the other side..
glassing vent top.jpg
glassing vent.jpg


We had to build the shape of the enclosure... We used some of the forms for the original JKU enclosures and pieced it together.
Side with seat.jpg



The seats down with the enclosure in place.
Side View.jpg



We finished up the enclosures and measured the internal volume to be .6 cu ft per enclosure.
Top view.jpg


Had them Line-X'd inside and out for sound deadening and because they look stealth under the seats.
sub enclosures.jpg


Here's a closure of the internal re-routing of the vent.
Sub closeup.jpg


Detail of the new rear vents.

vent.jpg
 
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Mattk11

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Since I am going three-way active in the front, I had to create pods for my Scanspeak tweeters. I had some PVC rings cut for the speakers to mount into, then used styrofoam to form the shape of the pod. Once the shape was finalized, I fiberglassed them. Many hours of sanding, filling and sanding,

tweet side.jpg
tweet mounted.jpg
they are ready for primer.

tweet front.jpg
 
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Mattk11

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I didn't want to use the back storage for the amps, but I am forced to do so because of the number and size that I am using. I cut all the pieces for the amp rack out of 1/2" mdf to make the template....that will be transferred to 1/2" PVC sheeting so the shelves are waterproof. I also mounted the amps at an angle so if some water does get into the storage area, it will run off and hopefully not cause any damage. The DSP and wiring distribution will be under the Sundown Audio amp out of sight.

Amp Rack.jpg
 
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Mattk11

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Sorry, skipped through a lot of the fabrication. I'm just not very good at taking pictures.

The install is done and I'm impressed even without the DSP being fully calibrated and EQ'd. My previous build in my JK was REALLY good in my opinion, but this time I took extra time and paid a greater attention to detail. Again, I wanted it to be as stealth as possible but there were some factors that could not be avoided. Some post install thoughts:

1) Again fabricated the Under-seat Subwoofers - These are even better than I had in the JK as they are a newer model, Sundown SD-4 that utilize a new NEO magnet and handle 600w each. They have much better surrounds that seem to be more capable of handling power, and they are stitched in place so driving them with 700-750w won't be a problem.
2) Decided to go 3-way in the JL, that meant that I had to fabricate tweeter pods. This is the dead giveaway that the system isn't stock since they had to be mounted on top of the existing dash speaker grill. I like the way the look, but if someone is intent on breaking in a stealing them, it won't be too hard. Oh well, new tweeters will cost me less that $500 plus time to replace if I ever have a problem. There is nothing else you can see in the Jeep that would lead you to believe there is an aftermarket stereo.
3) The system is Digital from the head unit back to the DSP. The great news here is that it is dead silent - no hiss or engine noise in the system.
4) I REALLY did not want to use the rear cubby hole for my amps but I had no choice since I am using three plus a DSP. I am very happy with how the amp rack turned out - I had previously tucked my two amps inside my JK dash. You will see in the pictures that the structure is 100% PVC plastic so it will be impervious to moisture. Of course the electronics are not, so I took some precautions to ensure that any water that gets in will not sit idle on the amps or DSP. two of the amps are mounted at an angle to promote moisture run-off. The sub amp has a small space under it so no water can get trapped. If I encounter rain with the top off, I will be sure to check the cubby for moisture when I get home.
5) I took some extra time to wrap all the cables and I'm glad I did. It looks great even though the people reading this are the only ones that will ever see it besides me and my son that did a lot of the fabrication and work. That includes my wife. I guess the guy that tunes my DSP will see it next week
6) The DSP has a very basic tune just to get me up and running. I set all the crossover points and set delay distances but have not applied any EQ. First, the Scanspeak tweeters are incredible. Honestly it sounds really good but I can perceive some problems with the EQ. Surprisingly the imaging is pretty good just by inputting the speaker distances. I am not running the rear speakers and yet the system sounds very encompassing. I am hoping that the professional I hired can get it dialed in next week. I have an AudioControl RTA and microphone on order but will have the base tune done by a pro, then I can tweak it for different pre-sets such as top on, top off, freedom tops off, rear fill, etc

Here are a few pics, sorry I didn't take more of the process itself. The dash mounted 3" midrange, I used a closed foam mounting cup so the speaker had a small enclosure. The foam is obviously flexible so it fits fine with the air vents down below.
Mid Cone.jpg


Here is the Midrange mounted in the dash location:
Mid mounted.jpg


Scanspeak Illuminator tweeter mounted in the custom fabricated pods:
Tweeter Detail.jpg


CDT 6.75" Mid-bass. I used the Scanspeak aperiodic vents just as I did in my JK build. These combined with the Arc Audio BX2 enhancement really adds mid bass that I did not have in my JK. There is actually some mid-bass punch and does not sound artificial. Here is a short explanation of BX2:

BX2 uses the principle of the missing fundamental, which creates the sensation of low frequencies by generating a carefully calculated series of harmonics designed to simulate the auditory experience in the human ear caused by the missing fundamental pitch.

These harmonics extend the perceived frequency response up to 1.5 octaves below the speaker cutoff frequency (f3) without perceived distortion, increased peak power consumption or peak speaker excursion.

BX2 technology allows the system user to experience dramatically improved levels of system performance, sound quality and improved low-frequency response by:
Speaker Pod Removed.jpg


Under-seat Sundown SD-4 in fiberglass enclosures. Internal volume is .6 cu ft and the woofers are powered by a newly released SFB1500D 1500 watt amp. Even better bass that I had in the JK. It actually makes me a little nervous because its too loud at 75% and isn't clipping. Tune next week will put me at ease.
Sub Side View.jpg


I pushed the seat all the way forward so you can see some of the woofer itself. When the seat is in it's normal position you can't see anything but the back of the enclosure.
Sub Rear View.jpg


The JL Audio DSP has a cool multi-function knob that acts as a master control. It lets me attenuate the bass. It also lets me change the pre-set with a push. Each pre-set is assigned a different color: Standard tune: white, top off: red, top on: blue, etc. I had to modify the auxiliary plug but luckily I found a washer that fit just inside the illuminated ring, painted it to match the interior and had to do some fabrication on the back side so I could keep the illumination that was already on the ring.
DSP Knob.jpg


Amp Rack all wired up and finished.
Amp Rack 1.jpg

Amp Rack 2.jpg


I'll update when I get it all tuned up next week. Happy to answer any questions.
 

Gaust

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Looks awesome and I bet it even sounds better! How high did you have to raise the seats for the subwoofers? Does the PAC unit have digital output? Do you have any pictures of the dash midbass with the aperodic membranes? I kept my midbass sealed but was thinking of adding the membranes at a later time.
 
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Mattk11

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Looks awesome and I bet it even sounds better! How high did you have to raise the seats for the subwoofers? Does the PAC unit have digital output? Do you have any pictures of the dash midbass with the aperodic membranes? I kept my midbass sealed but was thinking of adding the membranes at a later time.
I used the Ohio Deisel Parts front seat lift kit. They are essentially 1" aluminum spacers that allowed me a little more volume under the front seats for the subwoofers.

The PAC unit does have a digital output, so I have an optical cable running from behind the head unit to my JL Audio DSP. Dead silent - no hiss.

I searched and could not find a photo of the aperiodic vents. They were really simple, I just cut the hole in the back of the pod (so they face the front of the Jeep) and secured them with Gorilla 5 minute epoxy. I don't have measurements that prove that they added more mid-bass. But my ears tell me it sounds like I have better midbass than I did in my 2013 Wrangler without the vents and more than the stock Alpine system had in this JL.
 

Gaust

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Thanks for the info. I looked at doing subs under the front seats but couldn’t figure out how to get more air space without raising the seats.
I’m getting great mid bass from sealed pods. I made sure the whole pod was sealed and I covered it in dynamat. Might be the speakers I’m using. I have a few other midbass speakers I’m interested in trying so I may cut the back of the pods out or order a second set of meters pods to try an aperodic vent with.
 
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Mattk11

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I’m pretty positively I could have gotten .5 cu ft under the seat without raising it. My subs are Sundown SD-4 so they don’t have a pole vent and can be mounted right against the bottom of the enclosure. But I learned I had plenty of room to spare after fabricating mine with the risers in place.

Thanks for the info. I looked at doing subs under the front seats but couldn’t figure out how to get more air space without raising the seats.
I’m getting great mid bass from sealed pods. I made sure the whole pod was sealed and I covered it in dynamat. Might be the speakers I’m using. I have a few other midbass speakers I’m interested in trying so I may cut the back of the pods out or order a second set of meters pods to try an aperodic vent with.
 

Gaust

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I’m pretty positively I could have gotten .5 cu ft under the seat without raising it. My subs are Sundown SD-4 so they don’t have a pole vent and can be mounted right against the bottom of the enclosure. But I learned I had plenty of room to spare after fabricating mine with the risers in place.
I’ve got a pair of JL 10TW3 d4 subs that are shallow mount with no pole vent either. If it built an enclosure I’d have to move my amps which are under the seats. I was thinking of building fiberglass boxes between the rear seats and roll bar like the JL stealth boxes. Another option would be under the rear seat but then I’d loose the ability to fold the rear seat unless I pulled the box out.
 

DavidRam

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Looks awesome and I bet it even sounds better! How high did you have to raise the seats for the subwoofers? Does the PAC unit have digital output? Do you have any pictures of the dash midbass with the aperodic membranes? I kept my midbass sealed but was thinking of adding the membranes at a later time.
Thanks! Here it is:

IMG-20200205-140656840-HDR.jpg


IMG-20200204-154907427.jpg


IMG-20200204-155001675.jpg


IMG-20200205-151302349.jpg
 

onlyontwo

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@Mattk11 , would your son be up for building another JL wrangler box? I had one of his boxes in my old JK. I would love to be able to get my sub up front...

Cheers,
-Andrew
 
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