Surround Sound Build in 2021 Challenger


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On a short trip out of town recently I was listening to my vehicles factory installed stereo. I find it frustrating to no end that even with fader control set towards the rear the back speakers are barely audible (as they are mounted low in the back doors). That speaker placement is no good at all for surround. This is in a 2019 Pathfinder. I like my car audio (stereo) to come more from the sides (fader centered), or else more from the rear. Stereo via the front door speakers doesn't really do it for me, it doesn't sound natural.

I still have an older Pathfinder (now on its last legs) in which I added extra speakers in custom made enclosures tall enough to clear the back seats. I feed them from the rear outputs of a Rocktron Circle Surround decoder, the factory installed speakers were then all fed from the front outputs of the decoder. I get half decent surround sound with this arrangement. The older cars, virtually all of which had rear deck mounted 6x9's were the best for surround! New cars with the sound system integrated into the entire front console would be very challenging to customise!
Amazingly while I have to give some credit to Fiat/Chrysler for finally allowing FLAC decoders in their vehicles after many years of being limited to MP3s and WAVs, they still haven't figured out the gapless thing yet. This is in spite of partnering with established audio manufacturers (Alpine in my case).

Ironically, back in the dark ages of the 70s, I had both gapless and some damn fine true surround in my 60's vintage Mustang. They call that "Progress".
Finally finished, just need to get some bugs out.
1. Little vibration at front right, without sound system on.
2. Had front and rear camera installed, nice app, not quite dialed in yet.
3. All digital files in stereo, all FLAC any bit rate 16 or 24, connected via OEM center console USB hub plays perfect.
4. 5.1 surround digital files, USB connected to 5.1 decoder in glove box, having trouble. I am getting closer, but for some reason the 5.1 decoder wants the files to be exactly a certain way, so I have to keep reformatting, today I might get it figured out.
5. The sound: would like it to sound a little better. I just have to take time and sit in the drive way and use the JL Audio app to set all the DSP settings for stereo and 5.1, fade, balance, crossovers, etc.
Here is a picture with the two amps showing under a wood and plexiglass frame, matching trunk carpet, and side sub box.
Frustrating not to nail it right away, but I think I have done what no one I know of has done, so patience will be my friend.
Nice work! Car audio totally is a trial in patience, I have learned that! I've been working on my DSP settings for quite some time now. My Audio Control DSP let's me set everything from my laptop - but it really takes time to do a tuning. Lots of steps involved, and it's good to have a bunch of reference tracks to access. I've found that setting time delay per speaker is really helpful to get accurate staging. There's plenty of online guides to keep you occupied for days on end - which may not be a good thing! :D
Nice work! Car audio totally is a trial in patience, I have learned that! I've been working on my DSP settings for quite some time now. My Audio Control DSP let's me set everything from my laptop - but it really takes time to do a tuning. Lots of steps involved, and it's good to have a bunch of reference tracks to access. I've found that setting time delay per speaker is really helpful to get accurate staging. There's plenty of online guides to keep you occupied for days on end - which may not be a good thing! :D
Thank you for your positive encouragement, makes me feel good. True, I am super happy with the build but the sound, I think I have to slow down a bit and go park in a nice field and just allow some time to concentrate.
I have the JL Audio app, that only works on iPad or PC, I loaded it on iPad and takes some studying, but I believe I have the crossovers and the delays fairly accurate, but not happy with the EQ, so if I just slow down I should get there.
I also figure certain genres of music sound different, that is another curve I will have to do.
Not sure if you have multiple DSP presets you can switch between? I have 4, which is actually not enough! Audio Control makes a little remote knob that doubles as gain (I set it for subwoofer gain) and preset switching. Very useful. So for example you can have different presets for different music types. Or for different delay times (if I'm not driving I switch to a preset that focuses the sweet spot on the passenger seat :giggle: ). I keep one set to flat, to make it easy to A-B my tuning against a flat reference.

I highly suggest checking out Audio Frog's tuning guide, once I found this it really helped clear up many things for me. I was just fishing around for a while before this. The section on setting crossovers is really excellent. Good luck!
4. 5.1 surround digital files, USB connected to 5.1 decoder in glove box, having trouble. I am getting closer, but for some reason the 5.1 decoder wants the files to be exactly a certain way, so I have to keep reformatting, today I might get it figured out.

What did you expect from anything digital.

Digital is snickety. Analog accepts almost anything.
Having a little Bud and Jack tonight so I will share my final pictures.
I have found that all my audio projects can be overwhelming for me but I just keep scratching. I will post a bunch of pictures with captions above. NOTE: I had help with this project.
The USB for the 5.1 decoder is a little finnicky but I am learning and making substantial progress. It must be 32g FAT32 to work.
My Chinese 5.1 decoder is no longer available so I ordered two more from Amazon, I can return if needed, but I want to see if the new ones come with more than a brown wrapper and NO directions.
The stereo from the OEM head unit is optical out to the two DSP amps. The 5.1 is analog (RCA cables) out from the decoder to the amps.
I think I remembered everything, oh yeah 1 more, used sound dampening in doors and trunk, so my next project is a dominant cat-back exhaust, music and exhaust, and burn outs, I love freaking out all the uptight neighbors.









I thought I would post my findings on this thread, but I will also post the same on the Challenger build thread.
So I got This, no longer for sale 5.1 decoder, works well, remote is so/so and screen size is small. Most importantly it delivers true 4.0 and 5.1 decoding assuming you have your 32G FAT32 drive correct.
Just for the heck of it I purchased two of these new available ones, screen is larger and it shows albums, that is a big plus as the discontinued model only shows tracks. Remote is far more advanced. Has an actual instructions via Q code.
The big problem for me is we designed the unit to separate the screen plate to go from the unit in the glove box to center dash console.
Unfortunately the new version has a ribbon connection from screen to unit and looks like a no go, in my case, unless I want to do everything all over, which I don't.
So, if I wanted the new unit, it would have to be inside glove box only and I need a break from all this madness.
Here is the LINK TO INSTRUCTIONS OF NEW UNIT The two units I received, that I am not using are called HD920, they call it HD920PRO, but I think they are the same.
Well, as much as I want to be satisfied with my 5.1 surround in my 2021 Challenger, I just couldn't get there
Problems, basically boil down to $150.00 5.1 Chinese decoders, really crap.
First one would play my 5.1 files, but didn't show as artists or albums, only songs. The biggest problem when I got out of car, it would go back to song #1 on that particular thumb drive, not acceptable to me. It was nice, easy to separate screen from unit and mount on center console, use remote, etc.
The second one I bought, (the first one they stopped making immediately after I purchased), looked very promising. Could detach screen, except now it was a ribbon cable, little tiny wires all in a row to solder, not fun. I tried so many ways to get it to read the 5.1 or 4.0 files, but just couldn't would always read the album name, improvement over unit #1, played stereo files very well and even played the stereo files in 5.1 that didn't sound to bad, even put the vocals in center channel, but I knew it wasn't right.
So now after MUCH MUCH research, the only way to overcome this problem was to buy a Blu Ray player, but how many Blu Ray players and a somewhat reasonable price have a screen that shows titles, album artwork, etc.
I found on Ebay a open box Cambridge CXU Universal player for $1300.00, now I am about $2000.00 over budget, which really sucks, but I know if I can keep fighting I will get this.
I hope, I can mount the unit under passenger seat, detach screen bring it to front console, if the remote sensor is in the screen, that will be a bonus, or I can bring the IF sensor to the front. Because it plays all files including DSF files, I will not have to convert any of my music to lower compression. Actually, if mounted correctly I could use the disc tray and play hard discs, just an option, I do not want to do that, I only want to use USB files.
When the unit arrives from Canada next week, I will lay it all out on floor, with just a bunch of speakers (5) I have laying around and 1 sub, and experiment with settings EQ, even has Audessy to EQ, make a bunch of USB files, etc.
I know, when I read this, it makes my head spin and I have only learned this stuff since 2014, but it is a hobby and I am pushing myself. BTW, the Cambridge has great reviews just as good as OPPO but 4K came into play and there are better Blu Rays out there for less money, but ones with screens that show albums and track names, those are in the $7000.00's, because everyone uses there TV screen which I won't have.
Another reason I picked this is it has 8 RCA outs for speakers, and that is the way I set all my speakers/amps in car already. Many Blu Rays are HDMI out and I would have to start from scratch, the thought of that makes me sick, so I will avoid it.
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I have some pictures here that I will caption above each picture. In the living room I made a mock up of a 5.1 surround, using the new Cambridge player with active speakers. The speakers in the car are not active as they have the two amps to drive them.. What a project, is all I can say, but after two fails with Chinese 5.1 decoders I could not afford any more fails. The Cambridge CXU is flawless, would highly recommend for home use, plays everything. Discontinued like the OPPO's but I was lucky enough to find a new one from a seller in Canada.
This picture is work completed, beautiful, but I will need to add the new player on top of the amps under the clear plastic.

This picture is where the player will be mounted. I went to cabinet shop yesterday and ordered a custom box that will hold the unit in place. I hope to make a fancy emblem on top to do justice to the one I will cover.

This is a picture of my car mock up in my living room, testing everything conceivable.

The next three pictures are of SMALL 5.5" camera screen that is HDMI in from player that will be mounted somewhere at my center console.



This picture is all that will be coming out of rear to amps, etc and to front console, Short RCA's to amps under box, short power to under box, one pin with 20' IR extender for remote at front of car, one 20' HDMI for viewing the camera screen front of car, one 20' USB to use thumb drive at front of car, instead of having to open trunk.

External USB drive IN at front of car.

Lithium battery to power camera screen that reads from HDMI player, with extra charging battery pack.

This picture I am 15' away from player using all extenders, HDMI, USB and IR (little button top left of screen) for remote.

These last two pictures show the screen once it is playing, in this case a stereo DSF (SACD) file.
Now to get the cabinet built, and make it all look pretty, another month or so, but going to be great as I worked out all the bugs in my living room. Thanks for listening/watching.


It works, unbelievable. 6 months, 3 builds and too much money, it sounds so great. Guaranteed only 2021 Challenger with surround in existence. Possibly the only car outside of factory surround like the Acura in existence with surround that plays all formats, a non DVD-A aftermarket player..
Plays all formats via 32Fat USB, Blu Ray up to 24/96, DVD-A any version, SACD DSD (DSF File) up to DSD64, DTS any version.
I am so happy, has been exhausting. The kid that helped me, highly talented, really high end interior car fabricator was blown away.
He, talent aside, is typical of his age, ear bud, iPhone, playlist, stereo listener. His talent and my surround audio expertise coming together was something great. I knew what the expectation was to be, he went with me and followed my vision not worried about anything I threw at him.
When we where doing are tune via the JL AUDIO TUNER APP, we both where blown away. I am not ready to say yet, but I am inclined to say the very nearfield listening in the car is more intense than on the home rig.
The app allows you to select and play only one speaker, we where working on the sound of the center speaker, had Genesis SACD 5.1 Abacab on and Phil Collins vocals where ONLY coming out of center speaker, we felt like we where in the studio sitting and watching Phil standing at the microphone, unbelievable. Obviously too much hassle to do that all the time especially while driving but my friend was really blown away.
In the end as we where driving home, he said to me "honestly, even though I have done my fair share of audio installs, this is the best I have ever heard, and I am not saying that just because I was part of build."
I dropped him at his house around 11:00PM and drove 45mins to home playing the SACD 5.1 Jeff Beck's Blow By Blow, and just wanted to keep driving south bound.
Was so hyped up when I got home around midnight, I had to eat a marijuana gummy to settle me down.
A few tiny cosmetic things to do, 2 hours tops, we both need a break, and agreed to meet up in 4 weeks, plus need to actually use it for awhile and look for bugs or problems.
My only fear for now, as I am uneducated about home vs car audio products. Will the Cambridge home player stand up to the movement of being in a car. I am only ever using the USB input, I will never use the disc player which has moving parts and I am positive that wouldn't work.
I'll send pictures later.