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dummyvariable

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2022 RAV4 Prime SE
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Discussion starter · #1 · (Edited)
I've just finished an audio system upgrade and sound deadening installation on my 2022 Prime SE, and figured you all might want to see how it turned out, as well as some measurements I took of the efficacy of the sound deadening.

The components I installed were the following:
  • AudioControl LCQ-1 line out converter / equalizer
  • Audison SR4.300 4-channel D-class amplifier
  • Image Dynamics CTX65cs components
  • Image Dynamics ID8 V.4 D2 8" subwoofer
  • Blue Sea Systems fuse block
  • KnuKoncepts Kolossus Fleks 8-gauge power and ground wires
  • KnuKoncepts Krux RCAs
  • KnuKoncepts Kord Ultra Flex 12-Gauge speaker wire (for subwoofer)
  • Install Bay nine-wire speaker wiring (for audio signal and front door speakers)
  • Metra 82-8148 speaker mounting brackets (front door speakers)
  • Metra 72-8109 speaker wiring harnesses (front door speakers)
  • Metra 72-8110 speaker wiring harnesses (dash speakers)
  • A bunch of Dynamat Extreme
Because the right front speakers receive signal from both the headunit and the DCM, I picked up audio signal at the dash speakers instead of using a harness at the headunit (which would omit DCM signal). Each dash speaker has four wires running to it - two from the headunit (+DCM on the right side), and two that run from the dash speaker down into the door wiring harness and to the door speaker. This made the dash speaker a perfect place to both intercept audio signal from the headunit, but also to send audio signal back up to the front and into both speakers on each side. I clipped apart the looped wires on the Metra 72-8110 adapter harness, figured out which two were signal wires from the headunit and which two went to the door speaker, and connected to my nine-wire speaker wire as so:

Image


In the diagram above, light grey is white in real life, and teal is whatever the factory wire colors are, I didn't bother to write them down. On the left side of the car I sent signal down the green and green / black pair of wires in the nine-wire, and down the purple and purple / black on the right side, which made keeping them distinct when wiring them to the line output converter / EQ much easier. This leaves three of the nine wires unused in each nine-wire bundle; maybe I'll use them for something in the future. I then ran each nine-wire down the door sills and into the rear cargo area along the right side near the battery.

Back up at the dashboard, I traced the factory dash speaker bracket onto a piece of ABS plastic and cut two out. I opened up bolt holes and the speaker mounting holes with Forstner bits and secured the new tweeters with a dab of epoxy, then wired them to what will become the tweeter signal wires within each nine-wire bundle (white and white / black). All mounted up:

Image


Wiring was now complete at the dashboard, with signal being sent back from the headunit (+DCM) to the back of the car, then two pairs of wires from the back of the car on each side connected back in to the tweeter and door speaker wiring.

With the door panel off, I used about 2 1/2 sheets per door of Dynamat Extreme to deaden the inside of the door skin, the inner door frame, and the inside of the door panel itself:



Image

Image

Image


and installed the new midbass speakers using the Metra 82-8148 adapters. These needed a few tabs cut off to fit my specific speakers, but nothing a rotary tool couldn't handle in a split second. I added a bit of deadening in the speaker opening while I had the speaker out, and wired up the speakers themselves using the Metra 72-8109 harness adapters. At least on the front two doors, I had no polarity issues with either the dash speaker harnesses or the door speaker harnesses. The hardware that comes with the speaker adapters is extremely cheesy - I swapped out the weird cheap stamped nuts Metra provided for some real nyloc nuts before installation:

Image


The rear doors got a lighter treatment of sound deadening - I didn't feel like mucking about with the sticky goo they used to hold the vapor shield in place, so I deadened the inner door frame and the inside of the door panels, which used about two sheets of Dynamat per door. For some reason, the two boxes of Dynamat came as different designs, but they're both Dynamat Extreme and appear to have identical construction, if a different appearance. Weird.

Image

Image


In the rear, the little cubby above the battery seemed like a perfect place to build a subwoofer box without needing to cut into any panels or do too much fabrication around the factory plastic. I popped the panel off, sound deadened behind it, and sound deadened the spare tire well while I was at it. At some point I may remove the side panels from the cargo area and go nuts with sound deadening, but for now this is as far as I wanted to tear things apart:

Image


I also popped off the hatch trim and deadened the inside of the hatch and inner surfaces of the trim, but ya boy didn't grab any pictures of that. The cargo area + hatch took another 4 1/2 sheets of deadener.

Next up was the amp rack and subwoofer box...
 
Discussion starter · #2 · (Edited)
The 10 image attachment limit is giving me hives. Anyway, onto more wiring, the amp rack, and subwoofer box:

To the left of the battery and just aft of the fuse box is a flat area that was perfect to mount some wiring components. I cut a panel out of more ABS plastic and mounted my fuse block and a couple of relays that my driving lights need. The fuse block has four positions, of which I need two for the audio project and two for my driving lights. Normally I would use a larger fuse block with an ANL fuse or similar, but my amplifier requires only a 30A fuse, which is well within the capabilities of this fuse block and a regular ol' ATO fuse. The fuse block is wired directly to the battery with a very short run of 8-gauge wire, which is protected by some wire loom (and doesn't go anywhere near anything sharp anyway):

Image


In the spare tire well, I removed the chunky styrofoam block that holds up the spare tire and found a surprising amount of space, though not a ton of height - if you've got a hybrid or gas model, you'll have more height than I found. This was the perfect place to mount my audio components. The amp rack is made of 3/4" baltic birch marine plywood and wedges itself nicely in place. The amplifier stood a bit taller than I wanted once mounted to it, so I routed out the shape of the amplifier down until about 3/8" of plywood remained. This sunk the amplifier into the rack by 3/8" and gave enough room that the spare tire could still fit without touching the amplifier - there's about 1/4" of space between them, which should be plenty for a cool-running class-D amplifier. To keep the spare tire propped up off the amp and EQ, I added the thick strip of plywood you see running from left to right across the top of the amp rack - this is just taller than the amplifier, and holds the spare up the way the stock styrofoam block would have:

Image

Image


I painted the amp rack with a zillion coats of textured black paint to hide all the plywoodyness.

Wiring and each component is as follows:
  1. Signal from the headunit (+DCM) travels down the nine-wire that we hooked in at the dash speakers to the LCQ-1. The signal is split into the front channel and sub channel at the LCQ-1 - I am not using the rear channel right now, since I am leaving the rear door speaker setup stock for the time being.
  2. The LCQ-1 converts the headunit's signal (line-level signal) to a higher-voltage signal (RCA-level signal) that the amplifier likes. Note that the while the amplifier can also accept line-level signal, the LCQ-1 has a nice equalizer and some bass rolloff correction abilities that I wanted. In this setup, the LCQ-1 is a nice-to-have, not a need-to-have.
  3. RCAs carry signal from the LCQ-1 to the amplifier.
  4. The amplifier sends 130W RMS x 2 at 2 ohms to the subwoofer and 85W RMS x 2 at 4 ohms to the crossovers.
  5. The speaker signal from the front two channels of the amplifier is routed to the crossovers mounted to either side of the amp rack.
  6. The crossovers split the speaker signal by frequency into high-frequency signal for the tweeters and midrange frequencies for the midbass speakers in the doors.
  7. The crossover signals are sent up the white + white / black and grey + grey / black pairs in the nine-wire, where they are wired into the tweeter and into the pair of wires at the tweeter harness that send signal toward the door speakers, as diagrammed in the first post.
  8. The two subwoofer channels from the amplifier are routed to the subwoofer box where each channel is wired to one of the two 2-ohm voice coils on the subwoofer. I could have saved some wire by bridging the two sub channels at the amp, but this would have required me to splice wires together at some point, and I had a bunch of 12 gauge speaker wire anyway.
  9. The LCQ-1 senses audio signal and turns itself on automatically. The remote out wire from the LCQ-1 is wired into the remote-in wire on the amplifier, causing it to turn on. The amplifier I chose has its own turn-on detection, but I used the one from the LCQ-1 to ensure they always turn on together.
With all this mounted up, the spare tire still fits perfectly:

Image


...though unfortunately I can't make adjustments to the EQ with the tire in place. Oh well.

I then built a custom subwoofer box out of 3/4" MDF to fit into the cubby area. I don't have a lot of pictures of the build of this guy, but it was a lot of shaping and sanding and cutting compound angles to get as big of a box as possible that would still fit and allow the hatch floor to open. I also wanted to avoid having to trim the factory rubber cargo mat, so I built in a little "pocket" underneath that allows the part of the mat that would normally fit into the factory cubby to slide in. The box ended up right at 0.3 cubic feet (net of the subwoofer's displacement), which is on the small side for this sub but within spec. I added about half a bag of polyfil to help the box act as though it has a bit more air space. I painted the box with the same textured black paint:

Image


If you are going to do a sub box in the same location, be aware that you will be dealing with compound angles and curves - if you're fiberglass-savvy, this would be a good application. I found that a flap disc on an angle grinder was hugely helpful for quickly carving the MDF into shapes to fit in this area. I am about 95% happy with the fit of it, but I may rebuild this at some point to get a bit more air space and that much tighter fitment. Regardless, it looks good in person and sounds surprisingly good for as small a box as it is.

Overall impressions of the audio system:
  1. It sounds pretty good! I'm totally satisfied with the sound for the amount of money and effort I put into this. My experience with car audio is mostly in the show car world, where I have put dumb amounts of money into audio systems, so it of course doesn't compare at all to a competition system... but it is a vast, vast improvement over stock. My partner noticed the difference in sound immediately, and they are not someone who generally cares about this stuff.
  2. This is the first hatchback-shaped car I've had with an audio system in it, and I was worried that the 8" sub wouldn't be sufficient. It's in fact, perfect. On the very low-end, it can't compare to, say, the FI Q 12 on 1500W I had in my last show car, but it's plenty good, especially for a daily driver.
  3. I love how little space this installation takes up. I'd love if I could get to the EQ adjustments a little easier, but once I've got them dialed in, I shouldn't need to touch them again anyway.
  4. There's only so much you can do with a car with as much road noise and wind noise as a 5th generation RAV4. More on that in the next post.

Next: did all this sound deadening do anything?
 
Discussion starter · #3 · (Edited)
...and onto some sound deadening results.

If I had to levy one complaint about my RAV4, it's how noisy the interior is. There's lots of talk on here and elsewhere about whether sound deadening does much of anything on these cars, so I wanted to take some measurements to share. I took measurements of interior noise at three stages:
  • Stock
  • With just the front doors deadened
  • With all the rest of the sound deadening described above in place
To test, I measured sound level in the car at idle (which in a Prime or hybrid, is engine-off), under acceleration, and at freeway speeds. At each stage of sound deadening, I ran the same route under as similar conditions as possible: clear weather, light traffic, HV mode (to get some engine noise in the mix), roof rack rails on, moonroof and shade closed, HVAC fan on low. I idled for 40 seconds to get a baseline, then accelerated at maximum throttle to 100 km/h, then held 100 km/h using cruise control until I hit 90 seconds of measurements (so, another roughly 45 seconds or so).

Measurements of sound level were taken using a sound meter app on my iPhone, set to dB-A scale, with the phone set on a piece of soft foam in the tray in front of the shifter, microphone pointed toward the rear of the vehicle. The phone was left unplugged from the headunit so that the iPhone's microphone was in use, rather than the car's hands-free microphone. The app I used can dump measurements out to CSV, which are the recordings I used.

Measurements from the car were streamed off the OBD port using a Carista adapter -> OBD Fusion app, also dumped out to CSV. I recorded road speed (as measured by the car, so probably 2-3% higher than actual road speed) and engine RPM. OBD Fusion creates a record in the output file every half-second, which I joined to the nearest half-second in the decibel meter app's output.

Results are as follows:
  • At idle, there is little meaningful difference in measured or perceived noise level between stock and either sound deadening level.
  • At highway speeds, I measure about a 2.2 dB difference between stock and just the front doors deadened, and 4.3 dB difference between stock and all the sound deadening I put in. Perceptually, higher frequency road and wind noise seems noticeably more muted, though lower-frequency rumble is still there. It's no Mercedes, but it's better than it was.
Some charts from the data I recorded:

Image


Image

Image


The "notchiness" of the OBD readings is, I think, an artifact of my OBD reader - I suspect it and the OBD bus are not always quite in-sync, and it seems to fill in missing values with previous values. No idea why one run looks smooth and the other two notchy, but for the purposes of correlating road speed with cabin noise, it doesn't really matter that much.

Also, big caveat around the SPL measurements - an iPhone is far from a calibrated dB meter. I see odd spikes into surprisingly high readings (90-some dB at one point) that are probably an artifact either of the microphone itself or that I had the phone resting on the car, rather than mounted in some kind of shock mount. Perhaps that is the product of banging around over a pothole or something, or maybe just a loud vehicle going past my car.

Fun fact, I also got some measurements of 0-100 km/h times via these tests - my OBD reader only has 1/2 second resolution, but all three came in between 5.5 and 6.0 seconds. These Primes are quick little things!
 
Nice write-up, far more sophisticated and experienced than I can approach.

Have you done any sound deadening inside the hood? I don't know how the noise of the engine afffects interior audio at the levels that you are using. But as a basic radio and Spotify user, I could hear a reduction from putting dampening on the hood. The clips that hold the cheap molded foam panel are prone to break. I used some noico dampening and some Ebay cheap .200" foam with aluminum face. Took the mid/upper edge off of the engine noise slightly.

That mastic gummy mess on the rear doors isn't that bad to deal with, but I bet you've seen enough of that stuff to know exactly when you are up for dealing with it :)
 
Discussion starter · #5 ·
Have you done any sound deadening inside the hood?
I've not - I drive in HV mode so rarely that it just didn't seem worth the trouble.

And yeah, I was not in the mood to deal with the rear door vapor shield 😅 . I was so excited to see Toyota put in a nice, clip in vapor shield on the front doors, but then discovered the rear doors are still mastic-city back there. Anecdotally, the rear doors aren't where the bulk of the interior noise seems to be coming from anyway - it seems to be a mix of road noise up through the floor, fenderwells, and cargo area, as well as a truly wild amount of wind noise from the roof rack crossbars.
 
Yeah, I am picking up a lot from the upper 'C Pillar' area, if that is what it is called. behind the rear windows, upper area below roof. I did reach some small pieces of deadening into there. The little bit of overall deadening I did - doors, slight rear wheels reached in, spare tire, rear hatch- helped the overall buzziness of the car. But also made clearer the amount of road and tire noise! The rear wheel wells and front firewall would probably make a difference, but I don't care enough to make the effort for what could probably be a small improvement. Your almost 5dB improvement is nice, looks like the right balance of effort given what could be achieved in a Rav4.
 
Discussion starter · #8 ·
I was wondering where you got your 12 volt constant for the LOC
It comes off a 5A fuse in the fuse block I added (first image of second post), same source as the amplifier. The battery is just right there in that back right corner of the cargo area, which made for a short wire run to the fuse block.
 
I then built a custom subwoofer box out of 3/4" MDF to fit into the cubby area. I don't have a lot of pictures of the build of this guy, but it was a lot of shaping and sanding and cutting compound angles to get as big of a box as possible that would still fit and allow the hatch floor to open.
I am far from a car audiophile and I don't spend much time on the highway, but I've been considering some audio upgrades and sound deadening for all the reasons cited. This is a fantastic and detailed writeup on what you did and the results. Thank you.
Regarding the sub-woofer. instead of taking up deck storage space, did you consider a tire well mounted sub such as the JBL BassHub? I've seen a couple of sub's that could go into the wheel well without taking away from regular stowage space. I keep wondering if any of them are worth the price?
 
Discussion starter · #10 ·
I am far from a car audiophile and I don't spend much time on the highway, but I've been considering some audio upgrades and sound deadening for all the reasons cited. This is a fantastic and detailed writeup on what you did and the results. Thank you.
Regarding the sub-woofer. instead of taking up deck storage space, did you consider a tire well mounted sub such as the JBL BassHub? I've seen a couple of sub's that could go into the wheel well without taking away from regular stowage space. I keep wondering if any of them are worth the price?
Glad you found the thread helpful! According to others on here, the JBL BassHub won't fit the Prime. The Prime has a higher cargo area subfloor and the spare sits a couple inches higher than in the hybrid or gas models, so there's apparently not enough height to fit a BassHub and also get the cargo floor back in place. Otherwise I would have considered it. I did put some thought into making a custom enclosure within the spare tire to fit a shallow-mount sub, but it would have really required fiberglass to get adequate airspace, and I was just extremely not in the mood.
 
Nice write-up, far more sophisticated and experienced than I can approach.

Have you done any sound deadening inside the hood? I don't know how the noise of the engine afffects interior audio at the levels that you are using. But as a basic radio and Spotify user, I could hear a reduction from putting dampening on the hood. The clips that hold the cheap molded foam panel are prone to break. I used some noico dampening and some Ebay cheap .200" foam with aluminum face. Took the mid/upper edge off of the engine noise slightly.

That mastic gummy mess on the rear doors isn't that bad to deal with, but I bet you've seen enough of that stuff to know exactly when you are up for dealing with it :)
I did sound deadening on hood my 21 RAV4 Hybrid. I removed factory mat, applied Amazon basic sound deadening mat selectively on the hood and also added some sound absorbent from a washer machine. Then put back factory hood mat. I expected and did break all six factory hood clips. I ordered aftermarket clips from Amazon before hand. It did reduce the engine noise.

I also put some mass load vinyl sound sound isolation with 1" foam over the top of engine and between engine and firewall further reduced engine noise.
 
Just joined to say damn what an install - excellent job OP. I intend to copy the amp/loc mounting location. I think I'm going to be ultra paranoid and since I've got to run two sets of 8-wire conductors to the dash anyways (signal from radio and signal to speakers) I may put some quick connects at the trunk side so that in the event the amp has a problem I can "re splice" the factory wiring quickly.... Was an installer way back when and worked at a large aftermarket/oem audio company as well. This will be my first "system" in a car since the early 00's lol.... Current plan is JBL components up front, JBL co-ax in the rear doors, an old school clarion sub I've been saving since I don't want to say when, the SKAR custom box for the nook where you stuck your sub, LC5i Pro and an undecided 5-channel amp to power it all.... I have some old school clarion amp's I'd love to use, but given size and power requirements of the older stuff I think I've got to pass.....
 
It comes off a 5A fuse in the fuse block I added (first image of second post), same source as the amplifier. The battery is just right there in that back right corner of the cargo area, which made for a short wire run to the fuse block.
@dummyvariable how can i get in contact with you? I plan making some changes and audio upgrades to my coming car and would like to ask a couple of questions.
Thanks.
 
I had bought some KilMat about 2yrs ago, used some of it under carpet on my Lexus. I always had reservations of using the sticky stuff on vertical surfaces. I only used about half the box (sheets). Today I opened the box to get a sheet for some sound deadening on a dishwasher. My fears rang true. The sticky backer lost most of it's stickyness. The box was in my garage which can get as hot as 110F+ during the summer. Looks like the oil in the sticky part migrated out into the paper wax sheet that you peel off.
 
The 10 image attachment limit is giving me hives. Anyway, onto more wiring, the amp rack, and subwoofer box:

To the left of the battery and just aft of the fuse box is a flat area that was perfect to mount some wiring components. I cut a panel out of more ABS plastic and mounted my fuse block and a couple of relays that my driving lights need. The fuse block has four positions, of which I need two for the audio project and two for my driving lights. Normally I would use a larger fuse block with an ANL fuse or similar, but my amplifier requires only a 30A fuse, which is well within the capabilities of this fuse block and a regular ol' ATO fuse. The fuse block is wired directly to the battery with a very short run of 8-gauge wire, which is protected by some wire loom (and doesn't go anywhere near anything sharp anyway):

View attachment 196482

In the spare tire well, I removed the chunky styrofoam block that holds up the spare tire and found a surprising amount of space, though not a ton of height - if you've got a hybrid or gas model, you'll have more height than I found. This was the perfect place to mount my audio components. The amp rack is made of 3/4" baltic birch marine plywood and wedges itself nicely in place. The amplifier stood a bit taller than I wanted once mounted to it, so I routed out the shape of the amplifier down until about 3/8" of plywood remained. This sunk the amplifier into the rack by 3/8" and gave enough room that the spare tire could still fit without touching the amplifier - there's about 1/4" of space between them, which should be plenty for a cool-running class-D amplifier. To keep the spare tire propped up off the amp and EQ, I added the thick strip of plywood you see running from left to right across the top of the amp rack - this is just taller than the amplifier, and holds the spare up the way the stock styrofoam block would have:

View attachment 196483
View attachment 196484

I painted the amp rack with a zillion coats of textured black paint to hide all the plywoodyness.

Wiring and each component is as follows:
  1. Signal from the headunit (+DCM) travels down the nine-wire that we hooked in at the dash speakers to the LCQ-1. The signal is split into the front channel and sub channel at the LCQ-1 - I am not using the rear channel right now, since I am leaving the rear door speaker setup stock for the time being.
  2. The LCQ-1 converts the headunit's signal (line-level signal) to a higher-voltage signal (RCA-level signal) that the amplifier likes. Note that the while the amplifier can also accept line-level signal, the LCQ-1 has a nice equalizer and some bass rolloff correction abilities that I wanted. In this setup, the LCQ-1 is a nice-to-have, not a need-to-have.
  3. RCAs carry signal from the LCQ-1 to the amplifier.
  4. The amplifier sends 130W RMS x 2 at 2 ohms to the subwoofer and 85W RMS x 2 at 4 ohms to the crossovers.
  5. The speaker signal from the front two channels of the amplifier is routed to the crossovers mounted to either side of the amp rack.
  6. The crossovers split the speaker signal by frequency into high-frequency signal for the tweeters and midrange frequencies for the midbass speakers in the doors.
  7. The crossover signals are sent up the white + white / black and grey + grey / black pairs in the nine-wire, where they are wired into the tweeter and into the pair of wires at the tweeter harness that send signal toward the door speakers, as diagrammed in the first post.
  8. The two subwoofer channels from the amplifier are routed to the subwoofer box where each channel is wired to one of the two 2-ohm voice coils on the subwoofer. I could have saved some wire by bridging the two sub channels at the amp, but this would have required me to splice wires together at some point, and I had a bunch of 12 gauge speaker wire anyway.
  9. The LCQ-1 senses audio signal and turns itself on automatically. The remote out wire from the LCQ-1 is wired into the remote-in wire on the amplifier, causing it to turn on. The amplifier I chose has its own turn-on detection, but I used the one from the LCQ-1 to ensure they always turn on together.
With all this mounted up, the spare tire still fits perfectly:

View attachment 196485

...though unfortunately I can't make adjustments to the EQ with the tire in place. Oh well.

I then built a custom subwoofer box out of 3/4" MDF to fit into the cubby area. I don't have a lot of pictures of the build of this guy, but it was a lot of shaping and sanding and cutting compound angles to get as big of a box as possible that would still fit and allow the hatch floor to open. I also wanted to avoid having to trim the factory rubber cargo mat, so I built in a little "pocket" underneath that allows the part of the mat that would normally fit into the factory cubby to slide in. The box ended up right at 0.3 cubic feet (net of the subwoofer's displacement), which is on the small side for this sub but within spec. I added about half a bag of polyfil to help the box act as though it has a bit more air space. I painted the box with the same textured black paint:

View attachment 196486

If you are going to do a sub box in the same location, be aware that you will be dealing with compound angles and curves - if you're fiberglass-savvy, this would be a good application. I found that a flap disc on an angle grinder was hugely helpful for quickly carving the MDF into shapes to fit in this area. I am about 95% happy with the fit of it, but I may rebuild this at some point to get a bit more air space and that much tighter fitment. Regardless, it looks good in person and sounds surprisingly good for as small a box as it is.

Overall impressions of the audio system:
  1. It sounds pretty good! I'm totally satisfied with the sound for the amount of money and effort I put into this. My experience with car audio is mostly in the show car world, where I have put dumb amounts of money into audio systems, so it of course doesn't compare at all to a competition system... but it is a vast, vast improvement over stock. My partner noticed the difference in sound immediately, and they are not someone who generally cares about this stuff.
  2. This is the first hatchback-shaped car I've had with an audio system in it, and I was worried that the 8" sub wouldn't be sufficient. It's in fact, perfect. On the very low-end, it can't compare to, say, the FI Q 12 on 1500W I had in my last show car, but it's plenty good, especially for a daily driver.
  3. I love how little space this installation takes up. I'd love if I could get to the EQ adjustments a little easier, but once I've got them dialed in, I shouldn't need to touch them again anyway.
  4. There's only so much you can do with a car with as much road noise and wind noise as a 5th generation RAV4. More on that in the next post.

Next: did all this sound deadening do anything?
What are the dimensions for your subwoofer box?
 
Following for future reference...
For anyone else doing this, when applying CLD like Kilmat or any other brand you want to keep the pieces of CLD as large as possible. Cutting them up into tiny pieces significantly reduces their effectiveness at reducing panel resonance. Also, you'll get much better results if you can put some form of sound absorber on top of the CLD. Just don't put any sound absorber inside the inner door where it can get wet unless it's hydrophobic.
 
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