Replaced Bose subwoofer, again (2022 CX-9)

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22 CX-9 GT
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21 6 Carbon
This time I just replaced the 5.25" subwoofer in my 22 CX-9. Last time I added a 12" shallow sub.

Overall the sound quality of the 5.25" sub is better than my old 12" Infinity and I'm really impressed by its' output. I chose the Epique E150HE-44 5-1/2 by Dayton Audio, purchased at Parts Express.
https://www.parts-express.com/Epiqu...G-Subwoofer-4-Ohm-per-Coil-295-102?quantity=1

After playing with the sound settings in the new Bose infotainment software, I decided that turning on Driver and Linear sounded best to me. These are frequency responses of the various settings I tested, with the stock Bose subwoofer.

All settings off:
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Driver turned on:
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Driver and Linear turned on:
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The Epique 5.25" sub can handle 200 watts RMS and I had a Kicker 250 watt RMS amp in my parts bin so it was a good match. I also had a Wāvtech LinkDQ LOC and remote attenuator from my last install that I will use again.

I wanted to use as little space as possible and still have full unrestricted access to the spare tire. This time I put my amp and LOC in the storage under the rear mat. I built a shelf as small as possible. I used the storage insert as a template.
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Running the power and ground wires in the CX-9 is very easy. There is a grommet in the firewall that can be penetrated. There is also an unused input on the factory battery power block that can be used. I used my LOC as a remote turn on generator. It senses DC offset as well as audio and will turn on the amp. The CX-9 has DC offset on the subwoofer speaker wires but it comes on when the doors are unlocked or anytime the car "wakes" up. I chose to disable it on my LOC and only use the audio sense to turn on the amp, scared of unnecessary battery drainage.
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Grounded to bolt under 3rd row seat, after sanding to bare metal.
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I then slightly modified the factory Bose Bass Box to accommodate the new subwoofer. The Epique E150HE-44 is massive compared to the stock subwoofer. I had to add a .5" adapter to fit the new subwoofer. The mounting depth is massive so I had to cut out one brace inside the Bose Bass Box. I also added lots of sound deadening material to the Bass Box.
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Once the new sub was attached to the Bass Box, I tested it. I was surprised with its output. This driver has soo much excursion. I ran frequency sweeps on it and I assume the Box Bass Box is tuned to ~38Hz. this is the frequency where the driver moved the least.
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Next I installed the Bass Box back into its factory location. I had to leave the cover off it as well as rotate it, to make sure it didn't hit the storage insert. I had to lengthen the factory speaker harness.
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Next was time to complete the connections to the LOC and amp. I left enough wiring so I could easily move the storage insert to access the spare tire. I put the bass knob under the steering wheel, close to the driver door. I cut the speaker wire coming into the quick disconnect and ran it to my LOC. I then ran speaker wire back from my amp to the disconnect.
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Finally I connected the main power to the battery terminal.
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Finally time to hear how it sounds with the rest of the audio system. WOW, this little driver adds substantial low end. It compares to much larger drivers that I've used. My Kicker amp is rated at 250 watts RMS but can play clean 306watts RMS, tested with my pocket oscilloscope. I usually set up my sub amps with a -10dB test tone but this time I used a -5dB test tone and maxed the amp out with it. The LOC is such high quality that my amp gain is set to minimum and I still get full power, with the LOC outputting 5 volts max, turned up less than half way. I initially listened to some music and it sounded weird. I then ran some sweeps and found a huge null around 50-80Hz. I then swapped polarity on my amp and it fixed the null and everything sounded good.

Upon further investigation it appears the factory Bose sub has reverse polarity.
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These are the response graphs with the new sub installed, full gain. Crazy! The attenuator knob comes in handy.
All settings off:
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Driver turned on:
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Driver and Linear turned on, this is what I am using:
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Overall I am very happy with the outcome of this little sub.

Here is the electrical response coming into the sub, on various Bose settings and volumes of 40 and 25. 40 is the highest I go on this system and 25 is where I ran my sweeps.
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Graphs on top of each other to compare difference in sub output, stock vs aftermarket.
All settings off:
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Driver turned on:
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Driver and Linear turned on.
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Intriguing, and surprising that the smaller driver is 'better' than the larger one.

I wonder if the CX5 uses the same driver/enclosure, possibly able to do the same minimalist upgrade.

Did you make the baffle/adapter?

Thinking the Kicker 47KEY500.1 amp might be a good option to be able to flatten out the signal too.
 
Intriguing, and surprising that the smaller driver is 'better' than the larger one.

I wonder if the CX5 uses the same driver/enclosure, possibly able to do the same minimalist upgrade.
It all depends on the interaction between the enclosure and the driver.

It is all too easy to have a single 8 in the perfect enclosure outperform 4 12's in the completelly wrong box.

There are actually mathematical formulas that predict this behavior using the specifications of the speakers called Thiele-Small Parameters.

That's way beyond the scope of this thread though.
 
Yes, I made the baffle out of .5” MDF.

My 12” Infinity REF1200S was in a .8cuft sealed enclosure and sounded good. It was louder than the 5.25” but didn’t blend as well with the Bose system, no matter what the sub volume or crossover point. The Dayton 5.25” is tighter, digs just as deep and is still plenty loud. It blends better at the Bose crossover point. I’m not using the crossover on the Kicker amp, set to highest 200Hz. The Dayton has so much control and movement. It sounds better in the car with cover, carpet and mat than near-field. The enclosure is tuned perfectly for the Dayton sub and for the CX-9.

I was also intrigued by the Kicker auto correcting amp but would have to probably use less power with it, due to the boost it would introduce in the low end. It would be fun to see what it does though.
 
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