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Model 3 Trunk Insulation

58K views 221 replies 49 participants last post by  SoFlaModel3 
#1 ·
Anybody install this type of insulation in their model 3?

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#5 ·
I was told it was a port for the trunk mounted subwoofer. The low frequencies might make it through with it blocked, but I don’t think it’s to equalize pressure. If so it would need to be that big and I would need to be right in the middle.
 
#6 ·
I would be interested in that as you can easily hear things moving around in the trunk with the open port, but along with others concerns ... would want to know for sure why that opening is there and what happens if its covered.
 
#7 ·
I believe it would be much harder to close the trunk with a single swing, since the air pressure will build up with no outlet to go. Nevertheless, it looks nice.
 
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#8 ·
The trunk actually has exhaust vents in the rear corners behind the bumper, so closing it shouldn't be more difficult even if this insulation blocked the vent on the rear deck completely. But it almost looks like the slots on the left and right might let air through. I believe the primary purpose of the rear deck vent is as an exhaust for the air that the HVAC system pushes into the cabin from the front, so not blocking it completely would probably be better to ensure proper ventilation of the cabin.

Anyway, I'd also like to learn more about this insulation since a lot of the road noise seems to enter through the trunk.
 
#14 ·
The eBay mat is pretty neat. I wonder if it really would cut down on any road noise. The subwoofer is in the trunk, I also wonder if blocking the sound tunnel (opening for subwoofer) in roof of trunk would affect the quality of bass when listening to music. What do you all think?
 
#15 ·
Probably....my first thought as well. Will prob kill your bass. I thought that was an air pass through as well.

Ski
 
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#19 · (Edited)
I also read that the grill in the rear deck is a bass port. It only makes sense given that the subwoofer is placed facing the rear of the car in the trunk. In fact, I can't imagine why Tesla would have gone to the expense of putting in a hole in the rear deck with a grill if not for a bass port.
 
#17 ·
When I had my '12 & '18 Volts, a lot of us bought Volt Shelves to provide a rear deck to reduce road noise and reduce the cabin size that needed to be heated in the winter.

IF I knew this reduced noise noticeably, I'd be all over it.
 
#26 ·
I spoke with and audio engineer friend of mine and he believes the grill is the bass port for the subwoofer. It is sized to dump oscillations at the resonance frequency of the subwoofer. Also the newer subwoofers handle more than just the low frequencies. You might still be able to feel the thumping bass, but the sound will still be muffled. If some one has a SR/SR+ I would be willing to sell mine when evener it makes its way from China. They accepted my offer of $85, so I will be glad to let it go for what I paid for it.
 
#27 ·
I spoke with and audio engineer friend of mine and he believes the grill is the bass port for the subwoofer. It is sized to dump oscillations at the resonance frequency of the subwoofer. Also the newer subwoofers handle more than just the low frequencies. You might still be able to feel the thumping bass, but the sound will still be muffled.
You can easily test it yourself: block the opening from below using a piece of cardboard and listen (don't put anything on the vent from the cabin side, since that would block the two speakers that are next to the opening under the vent). I tried and couldn't hear a difference. Remember that the subwoofer is already behind the trunk liner, so any higher frequencies emitted by it would already sound muffled. But given the number of speakers in the cabin when you have the premium sound system, I find it hard to believe that the subwoofer is contributing anything but very low frequencies.
 
#28 ·
Some info from Wikipedia. I think pressurizing the subwoofer will affect the sound, especially at its resonance frequency.


Bass reflex enclosure schematic (cross-section).

RCA bass reflex shelf stereospeakers.
A bass reflex system (also known as a ported, vented box or reflex port) is a type of loudspeakerenclosure that uses a port (hole) or vent cut into the cabinet and a section of tubing or pipe affixed to the port. This port enables the sound from the rear side of the diaphragm to increase the efficiency of the system at low frequencies as compared to a typical sealed- or closed-box loudspeaker or an infinite baffle mounting.
A reflex port is the distinctive feature of this popular enclosure type. The design approach enhances the reproduction of the lowest frequencies generated by the woofer or subwoofer. The port generally consists of one or more tubes or pipes mounted in the front (baffle) or rear face of the enclosure. Depending on the exact relationship between driver parameters, the enclosure volume (and filling if any), and the tube cross-section and length, the efficiency can be substantially improved over the performance of a similarly sized sealed-box enclosure.


Contents


ExplanationEdit


Two inch port tube installed in the top of a Polk S10 speaker cabinet as part of a DIY audioproject. This port is flared.
Unlike closed-box loudspeakers, which are nearly airtight, a bass reflex system has an opening called a port or vent cut into the cabinet, generally consisting of a pipe or duct (typically circular or rectangular cross section). The air mass in this opening resonates with the "springiness" of the air inside the enclosure in exactly the same fashion as the air in a bottle resonates when a current of air is directed across the opening. Another metaphor often used is to think of the air like a spring or rubber band. The frequency at which the box/port system resonates, known as the Helmholtz resonance, depends upon the effective length and cross sectional area of the duct, the internal volume of the enclosure, and the speed of sound in air. In the early years of ported speakers, speaker designers had to do extensive experimentation to determine the ideal diameter of the port and length of the port tube or pipe; however, more recently, there are numerous tables and computer programs that calculate, for a given size of cabinet, how large the port should be and how long the tube should be. Even with these programs, however, some experimentation with prototypes is still necessary to determine if the enclosure sounds good.

A small JVC speaker with a port.
If this vent air mass/box air springiness resonance is so chosen as to lie lower in frequency than the natural resonance frequency of the bass driver, an interesting phenomenon happens: the backwave of the bass driver sound emission is inverted in polarity for the frequency range between the two resonances. Since the backwave is already in opposite polarity with the front wave, this inversion brings the two emissions in phase (although the vent emission is lagging by one wave period) and therefore they reinforce each other. This has the useful purpose of producing higher output (for any given driver excursion compared to a closed box) or, conversely, a similar output with a smaller excursion (which means less driver distortion). The penalty incurred for this reinforcement is time smearing: in essence the vent resonance augments main driver output by imposing a "resonant tail" on it. For frequencies above the natural resonance of the driver, the reflex alignment has no influence. For frequencies below the vent resonance, polarity inversion is not accomplished, and backwave cancellation occurs. Furthermore, the driver behaves as though suspended in free air, as box air springiness is absent.
When speakers are designed for home use or for high-volume live performance settings (e.g., with bass amplifier speaker cabinets and PA system speakers and subwoofers), manufacturers often consider the advantages of porting (increased bass response, lower bass response, improved efficiency) to outweigh the disadvantages (port noise, resonance problems). The design is popular among consumers and manufacturers (speakers cabinets can be smaller and lighter, for more or less equivalent performance) but the increase in bass output requires close matching of driver, the enclosure, and port. Poorly matched reflex designs can have unfortunate characteristics or drawbacks, sometimes making them unsuitable for settings requiring high accuracy and neutrality of sound, e.g. studio monitor speakers for use by audio engineers in monitoring facilities, recording studios etc. However it is possible to design a bass reflex system that mostly overcomes these drawbacks; and quality bass reflex designs are commonly found in demanding environments across the world.
 
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#29 ·
Some info from Wikipedia. I think pressurizing the subwoofer will affect the sound, especially at its resonance frequency.
The trunk has exhaust flaps under the liner, so it's not a sealed enclosure even if you block the vent 100% airtight. This also means the vent cannot function as a bass reflex port. Besides, the Model 3 subwoofer enclosure already has bass reflex port.

But anyway, no need to theorize, it's easy enough to try yourself. ;)

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#39 ·
Which eBay seller did you order from and how long did it take for delivery? Most I've seen say about 4 weeks.
Looks like you got a good product and well packaged. Will be waiting for your install comments in a few days .......along with pics, pics, pics of course. :)
 
#34 · (Edited)
Ha pics pics pics.

Packaging was a large woven bag (almost like a potato bag).

The trim was folded in half along a natural existing mold bend... no damage, creases etc. No rolling no extra folding.

There is also a tiny hardware bag inside with some items. Screws with washers, adhesion promoter sachet and metal shims (no instructions and aside from the screws, no idea what the rest is used for).
 

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#47 ·
Ha pics pics pics.

Packaging was a large woven bag (almost like a potato bag).

The trim was folded in half along a natural existing mold bend... no damage, creases etc. No rolling no extra folding.

There is also a tiny hardware bag inside with some items. Screws with washers, adhesion promoter sachet and metal shims (no instructions and aside from the screws, no idea what the rest is used for).
So you have a "Port" you're covering up with that or no port?

Ski
 
#50 ·
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