For this project, I replaced the rear door speakers with coaxial speakers to get a bit more dynamic range. The rear door speakers are identical for all cars, but Ultra High Fidelity (previously called Sound Studio) adds two 3″ speakers on the hatch to improve the high-end, so it may be less important for a car equipped with Ultra High Fidelity sound. This project results in no visible interior changes that make no new holes in the car or wiring changes, and while the old speakers are removed, they are easily reinstalled. The estimated effort is about 90-120 minutes per door, depending on your expertise.
The Tesla speakers are a single molded assembly custom-designed for the Model S with the following specifications:
Impedance: 2 ohms
I was unable to locate an identical speaker replacement, both in size or impedance, but the Focal 165 CA1 came fairly close and was chosen for this project. There is limited room behind the speaker, so any speaker beyond about 2-5/8″ depth may not fit. While 2-ohm impedance is preferred, the use of 4-ohm speakers will reduce the volume by about 3 dB (a small amount). The impedance is less important if you are adding separate amplification.
You can jump to my conclusions at the end to see if this is worth undertaking this change for your car.
We used a set of Focal coaxial speakers (each package includes two speakers). I’m sure there are others you can use, both from Focal or other vendors. These are key specifications of the 165 CA1:
Diameter: 6.5″ (165 mm)
Impedance: 4 ohms
RMS power handling: 60W
Sensitivity: 92 dB
I’ve assumed the non-Ultra sound is about 25 W RMS per channel. Tesla rates the system at 200 W for 4 channels, but since they don’t include RMS, it’s likely this is a peak power specification or 100 W RMS. Even if you have Ultra High Fidelity sound, which is 580 W, if they power the 7.1 channels equally, we look at something like 36 W RMS per channel, so these speakers should be fine in all cases.
Additional parts required:
Metra – Universal aftermarket speaker installation kit 82-4600 (has parts for two speakers)
2 ft of 16-18 gauge wire pairs (red/black or other)
4 – Solderless terminals, female (or solder wires to speaker tabs)
Removing the Door Panel and Old Speaker
The door is fairly easy to remove and with practice can be done in about 5 minutes if the tools are handy. First, remove the black rubber pad at the bottom of the hand-hold. It should pry out using a plastic tool. Remove the bolt hidden behind the rubber pad.
Behind the inside door release lever is a hard, black plastic cover. With the lever in its maximum open position, pry this part out from the front. It should come out easily. Remove the two bolts behind this cover.
Using a plastic pry tool at the bottom of the door panel, pry out the panel from the doors. Avoid using anything metal to prevent scraping the paint.
There are a number of snaps (that make a bad sound when releasing), around the outsides of the door. I found once you get a few to release on the bottom, you can get your hands between the metal door and the door panel and pull out. There are about 6 very hard snaps at the top. Pulling the top away from the door will release them. There are wires attached between the door and the door panel, so don’t pull so hard as to rip out the wires!
With the panel lose, unclip all the electrical connectors. Most of these have a latch that must be depressed to allow it to release. Do not force! With the panel detached, I put it in a safe place where it wouldn’t get dirty or scratched. On the door the Tesla speaker is visible.
Unclip the connector at the top of the speaker. There are two sides that must be spread out to release the connector. Remove the four Torx T-25 screws around the outside of the speaker mount, and remove the speaker.
Making a Replacement Mount
The universal installation kit has the parts you’ll need to make a speaker mount. It’s not perfect, but with some adjustments will work. There are three rings. We’ll only use the two angled rings, adjusted so they have the maximum angle. You may want to get a feel of how these all go together and mount to the flat plate. The flat plate needs to be cut so it’s about the same size as the original Tesla speaker’s mounting and four holes drilled for the mounting. Use the Tesla speaker to make a paper template to see where to cut. Be sure the mounting holes for the Tesla speaker do not overlap existing holes. Check how it will all go together carefully BEFORE cutting to be sure it will work. Remember the rings are positioned so the thin part is at the top and the bottom sticks out more than the top.
As you start to see how this all will fit together, you’ll discover you can’t get the four holes to all to reside outside the speaker rings. The solution has the bottom two holes on the outside the ring, similar to the Tesla original, and two holes are inside. My first round had had the mounting holes 1/4″ too low. The upper holes need to reside right under the ring (at a point where you can’t screw them in. I then made the top two holes as slots (not shown), so when mounted you can put the top screws in snug, but not super tight, and then slide the plate down so the screws are under the ring, then put the bottom screws in. You’ll also need to file some slots in the ring so the top two screw heads fit without binding once you slide it down when mounted.
Mounting the Speaker
With the plate made, attach ONLY the lower angled ring to the base plate. Attach the speaker to the upper angled ring. For me, the speed clips in the package only worked on two of the four holes. I had to use some machine screws and small nuts with lock-washers to attach the other two screws. Later we will install the base plate to the door without the speaker and top ring. The 3 screws to hold the speaker/upper ring to the lower ring is installed last.
Dry-fit everything together and see that it fits the speaker opening and the holes all align up. The bottom of the speaker will stick out the furthest, similar to the Tesla speaker.
Optional – I cut out some speaker damping material to match the size of the base plate, avoiding covering the mounting holes and speaker hole. Remove the adhesive backing and attached it to the bottom of the plate. A better seal between the door and the back of the speaker should improve the bass slightly and may reduce the chance of rattles. If you examine the original Tesla speaker, you’ll see that they put felt on its mounting plate.
Attach the speaker plate to the door with the four Torx screws from the Tesla speaker, but feed the wires under the mount up near the original speaker connector so about 6″ remains on each side of the mount.
Attach the wires to the speaker. I used some solderless terminals, but you can solder the wires if you prefer. Note the positive and negative markings and make sure you connect the wires to keep the polarity correct. For example, connect a red wire to the plus terminal, and a black wire to the negative terminal. With the wires attached, mount the speaker/top-ring assembly with the three screws. The top-most screw may be too long, so you may have to find a slightly shorter screw so it doesn’t touch the metal in the door. As you close it up, be sure the wires are not going to interfere with the window operation.
Attach the wires from the speaker to the connector. The green/black wire is the negative, and green is the positive (right door side, left side is purple/black and purple). With quite a bit of searching, I was unable to locate a mate to this connector. Depending on what you have handy, you might be able to make a male connector, or cut the Tesla connector and connect the wires up directly.
Test that the speaker is working correctly.
Attaching the Door Panel
An inverse of the removal, connect all the wires from the door panel and start at the top and press in the snaps. Check that the white serrated snaps are poking into the receptacles (sometimes they miss, making it impossible to secure the door). Proceed around the door, pushing in all the snaps. Screw in the three bolts and return the rubber pad and plastic insert.
Here’s a plot of the audio with the before and after results. Tests were at the lowest level “9” volume, tone controls at zero, and 100% of the sound coming only from the speaker under test. All test sounds were generated from an Alan Parsons Test CD, transferred to lossless FLAC files on a USB flash drive. All windows were closed, HVAC off and it was quiet outside when the testing was done. The test car also does not have the pano roof, which should reduce some sound reflections. The microphone was placed above the center-back of the arm-rests (not ideal, but adequate).
The matching peaks and dips are more likely due to resonance in the car at specific frequencies and not the speakers. The relative differences are more interesting.
For a car without Ultra High Fidelity sound, this is an incremental improvement that may not be worth it to everyone. It does improve the sound for the back-seat passengers. After a bit more critical listening (in the front seat) and the fader set a little more to the back, I’m finding the overall sound is better. I’m now happy I did the project and the sound seems more balanced. The bottom end bass is still lacking. See our Sub-woofer and Amplifier Installation project to further improve the sound!