# Alpine/JL Replacement of Jeep 6 Speaker System



## fusseli (May 1, 2007)

So I just got a new Jeep, it has the Uconnect system with 6 speaker sound. For my 6 speaker system, speakers are a pair of 3.5" in the dash (8Ω), and 6x9s (4Ω) in all four doors. The system actually sounds really good considering the stock speakers are usual paper cones ($7/ea Mopar). They are clearly putting a lot more effort into making the same old cheap speakers sound good and I have no doubt that the Uconnect system is working some factory calibrated magic to help the sound, and likely already has preset time alignment and such. The system is bass thick, by ear I'd guess it's good down to the 60s, I set the EQ to -2 on the bass, +3 mids, 0 treble and have been satisfied for now. It really reminds my of the Bose system in my buddy's Silverado, the first impressions are good then once you listen for a while it's grating. I didn't opt for the premium option, 9 speaker 506W Alpine branded system, after seeing the total option is $1200 (with the nav system also), reading that it was mostly the addition of a tiny sub module, simple upgrade to poly cones ($20/ea Mopar) on the woofers, and the addition of two more 3.5 inchers in the back. Reviews show people are pretty satisfied with both sound systems. As an audiophile I am not.

What I can't decide is how to upgrade the speakers in the front, the logical first step. The separation from the doors to the dash is so great that it makes me not want to install component speakers and put tweeters in the dash. I like the Alpine SPR-70C, as I have the previous model in another car and liked them a lot, they could be mounted apart or totally in the door, disabling the dash 3.5", with a 6x9 adapter. Another promising option is the Focal ISS 690, which is a relatively rare 6x9 component set with 1st-order crossovers which I think would be the best-case for mounting a tweeter 2'-3' from the woofers.

Then my wild plan B that appeals the most to my engineering instinct is to design my own proper system with a 3.5" in the dash and a mellow ~300Hz crossover to a 6x9 or 6" midbass in the door like the CDT CL69. The downer there is that there are very few high end 3.5" car audio speakers, the JL C2-350x is about as good as it gets. I have a woofer tester to I could easily buy any sets of speakers I want and properly size 1st-order filters for them. Plus how much better could a 1" tweeter with a 1st order HPF be, even if it's from Focal, than a decent 3.5" coaxial? That being said, what about something like the W3-1053SC :scratchhead:

Thoughts or ideas? Speaker suggestions? Permissible mounting depths: 2" on the dash and ~3.25" in the door.


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## fusseli (May 1, 2007)

*Re: New system, help my decide what to do!*

Here are some pics


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## Mike0206 (Jul 14, 2013)

fusseli said:


> Here are some pics


 I'd love to help you out but I don't know nearly as much as you about this stuff. I had a 2004 srt-4 and did an infinity kappa component system with 6" woofers in front doors and the tweeters were mounted on a flat spot on the top of door panel where the side view mirrors mounted. It was too much work to put them in the dash where they did have spots for them to go like your jeeps existing speakers in dash. Nice ride though! I've had 3 jeeps and 2 of which were grand Cherokees (2001 Laredo and 2005 Limited) and loved them all! I'd love to get a new one especially the v6 diesel but no need for a new car right now.


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## r.kuenen (Apr 13, 2014)

*Re: New system, help my decide what to do!*

I don't know this car in particulate but tweeters below in the door is no option because you lose to much high frequencies. As you maybe know, any speaker performs best in a sealed (or calculated vent-)box. All speaker mounts in the dash i know, have a wide open space.

I think the best way to go is a composet with separate tweeters like the Focal you mentioned. 
Most sq competition cars use this kind setup.

The downside of this option is the optical aspect.


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## fusseli (May 1, 2007)

*Re: New system, help my decide what to do!*

Right now I am considering going with JL C2 coaxials in the dash, and maybe C2 or C3 midbass in the doors, and design my own crossover between the two.

I just don't feel good about putting a fullrange 3" in the dash since it would beam above a few kHz and it would be aimed more or less at the windshield, and no tweeter will do the 200-300Hz extension that's needed to bridge the gap from the dash to doors. There are some good options from TangBand and the like, but I'm not finding many 4 ohm options that work well in sealed boxes with a high Qtc.


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## r.kuenen (Apr 13, 2014)

*Re: New system, help my decide what to do!*

Can you give some answers to the following questions?
- How much money do you wanna spend on your system.
- What level of sound quality do you expect.
- Do you gonna use a separate amplifier?
- Is it a must to keep the car interior OEM. So would you consider a speaker above the dash or another place if it's benefit to the sound quality.


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## fusseli (May 1, 2007)

*Re: New system, help my decide what to do!*

I might add an amp someday. A few hundred bucks on speakers in the front is fine. Interior must remain as original in look as possible.


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## r.kuenen (Apr 13, 2014)

*Re: New system, help my decide what to do!*



fusseli said:


> Right now I am considering going with JL C2 coaxials in the dash, and maybe C2 or C3 midbass in the doors, and design my own crossover between the two.
> 
> I just don't feel good about putting a fullrange 3" in the dash since it would beam above a few kHz and it would be aimed more or less at the windshield, and no tweeter will do the 200-300Hz extension that's needed to bridge the gap from the dash to doors. There are some good options from TangBand and the like, but I'm not finding many 4 ohm options that work well in sealed boxes with a high Qtc.


I think that this is not a bad option, considering your wishes in your last post.

As you sad before, there are not a lot of 3,5" speakers...


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## fusseli (May 1, 2007)

*Re: New system, help me decide what to do!*

I got a hold of JL and one of their techs agrees with me! So I'm going to stick to my plan rather than go with his suggestion: dash C2-350 coaxials with 6dB HPF around 200-300Hz, door C2-570 with matching 6dB LPF and 6x9 adapters.



Me said:


> I have a 2014 Jeep Cherokee with 6 speaker factory system. I am looking for a proper solution to upgrade the front speakers and I am not running into many sensible options. The front is shallow 6x9s in the doors with 3.5" in the dash. Mounting tweeters in the dash and midbass in the doors is not right and I won't consider it. Putting full range components or coaxials in the doors and disabling the dash speakers is doable but less than ideal.
> Right now I am considering C2-350 coaxials for the dash, and maybe C2 or C3 midbass woofers in the doors using some adapters, and designing my own simple 6dB crossover between the two. I would consider using a C2-690 in the doors and disabling the tweeters, but the mounting depth is likely a no-go. What do you guys suggest.





JL Audio Technical Support said:


> I'm very happy to read what you wrote about speaker placement. Most shops will totally disregard the separation between the woofer and tweeter which will highly affect sound quality. I will suggest something we do here at JL Audio on all our demo vehicle that will work in yours. Use a coaxial speaker for the door location,and add an ambient tweeter at the stock location. This will lift and expand the imaging. I have personally done it, and love it. We sell the separate tweeter that includes its own crossover which you can connect in the input side of the main crossover.


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## r.kuenen (Apr 13, 2014)

*Re: New system, help me decide what to do!*

Good luck with you build and let us know how it sounds. :TT


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## fusseli (May 1, 2007)

*Re: New system, help me decide what to do!*

Finally moving forward. I decided to go with the JL C2-350x for the dash and Alpine Type-R SPR-69 6x9s for the doors since they use neodymium motors that are a slim fit and will drop right into the stock location without modification.

I got a pair of the SPR-69 in the rear doors along with a little bit of vinyl damping material to hopefully reduce rattles. Just that change smoothed up the bass a bit. I'm now starting to work on the fronts. I'm waiting for the C2-350xs to show up but until then I'm playing with some crossover points. Going 1st order butterworth between the doors and dash, probably in the 300-500 Hz range. Here is the thiele small (T/S) parameters for the Alpine SPR-69. I removed the tweeters and removed the crossovers for the pair going up front. The stock speakers are the usual suspects.


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## fusseli (May 1, 2007)

I got mostly finished today. I ended up deciding to try the 1st order Butterworth slopes with passive filters as planned. Using the measured impedance data of the drivers, I came up with a 1.0mH coil for the LPF and an 80uF cap for the HPF, putting the crossover somewhere around 400 Hz. The 13550 criterion says the drivers shouldn't cross above about 450Hz given a ~30" separation. It's more or less a 3-way system up front now since the 3.5" coaxials also use a 1st order Butterworth on the tweeter. I can attach the PCD7 file that I used if anyone is curious, or wants the impedance data. There's a resonance at 180Hz from the midrange HPF that kind of worried me that I chose to ignore (no room for a big RLC contour filter) that possibly appears in the measurements as the blip at 180Hz. Also attached are a few quick sweep in REW with the mic pointed straight up.

I also applied some 3M asphalt dampening while I was on there, one door kit on either front door. I used foam gasket tape on all six speakers for a tight seal.

The results are good so far. The whole sound stage is dramatically lifted upward in front, it is a major change for the better. The stock dash tweeters were more or less ambient fill, whereas there's now the majority of everything above about 400 Hz coming from that location. The JL C2s as a midrange work well and sound good so far. Everything is clearer and bass is also majorly improved. A ballpark with my measurements is that there's +9dB at 30 Hz over the stock system, and transient response sounds faster and smoother. The SPR-69 woofers modified for midbass duty blend right in and can't be located, imaging comes only from the dash.


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## fusseli (May 1, 2007)

I did some RTA and more measurements today. With a lift in EQ in the midrange it's sounding good but but not quite right. I had skipped an LCR contour/notch on the midrange to damp the resonance at 180Hz predicted in PCD. It turns out, that resonance is definitely there. I defeated it be removing the series cap HPF and am now using the natural roll of of the 3.5" mid, which models to be at about 180 Hz, no coincidence since that's the Fs of the mid driver. With the cap removed and polarity flipped with the LPF still on the woofer it seems much better. This makes the acoustic crossover point about 180 Hz with 1st order Butterworth on the door with 180 Hz second order roll off on the dash.

Here's a measurement with only the left speakers active, including front and rear, dash midrange series caps removed. It is decent overall besides the null at 132 Hz and the cabin boom at 45 Hz. Nice bass for no subwoofer. Also attached is the RTA showing the unwanted resonance in the midrange from the series cap along with the prediction in PCD. Modeling can definitely be trusted  Also included the approximate predicted off-axis (driver's seat position respect to front left speaker) response from PCD, which doesn't include cabin gain. The overall characteristic matches well, the same dip below 1kHz and rise below 300 Hz.


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