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Add Polyfil to factory subwoofer

leonar40

Member
Jan 6, 2021
189
98
Bloomington, IN
As many of us have discussed, the factory subwoofer in the Model 3 Premium stereo is, well, underwhelming would be generous. A trick I've used successfully for small boxes like this one in the past is to fill it with Polyfil. This supposedly slows the sound waves down inside the box and makes the box "play" as if it's bigger than it's actual dimensions.

Good news is that adding it is easy. The factory subwoofer is located in the right side of the trunk, behind the carpet trim, directly underneath the right LED light. There is one trim clip to release and then the carpet just pulls back from the trunk gasket. From there you can see the subwoofer and plastic ported enclosure. I stuff Polyfil into the port and pushed it down into the enclosure using a flexible ruler until it was flush with the port. I stopped there so as to not pack it down too tight. I put the trim back together and tested it out.

Bad news, the results were disappointing. It certainly did not make the noticeable improvement I have experienced on other systems, and if anything, perhaps I notice a big LESS bass response. Although that could just be a placebo since I'm listening specifically for it. Either way before or after it's not very good. Shame because the rest of the system is quite good in my opnion.

Thought I would share my story in case anyone else has done the same (and maybe got a better result?) or perhaps this convinces you not to bother if you were thinking about it. On to the real subwoofer install later this spring. I'm going to put the sealed 12in. JL Audio Powered Subwoofer in the sub trunk. Since the power tap is at the back seat and the signal wires are right there at the factory subwoofer, it should be a relatively easy install. Fingers crossed!
 

Ravire

Member
Feb 13, 2020
177
121
Orange County
On to the real subwoofer install later this spring. I'm going to put the sealed 12in. JL Audio Powered Subwoofer in the sub trunk. Since the power tap is at the back seat and the signal wires are right there at the factory subwoofer, it should be a relatively easy install. Fingers crossed!
This is exactly what I did. You won’t be disappointed!
 
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webwarmiller

Member
Feb 4, 2021
26
27
dallas, tx
Another thing you could try is plugging the port (along with polyfill). I've never been a fan of bass reflex enclosures in automotive environments. They have a 24db/octave roll-off while sealed enclosures roll off at 12db/octave. When you take into account the fact that cars typical have a cabin gain that is about 12db/octave starting at around 90-100 Hz you can see why sealed enclosures work quite well in them.

I have an SR+ but recently had an LR loaner so I took the opportunity to perform an RTA on the premium audio (EQ set flat, immersive sound off, fader center). The red line is what I have set as my 'reference' curve which is based on the one from Harman International; it's what I target when setting up an audio system.
Screenshot_20210316-204323_AudioTool.jpg


Tesla did a pretty good job in tuning the system with the exception of that dip centered somewhere btw 3.5-4kHz (second to last EQ slider can help a bit but it seems to be centered around 2kHz unfortunately). As for the sub you can see about a 12db/octave drop off starting at around 40Hz. This is telling the the enclosure is most likely tuned to around 40-45Hz or so. The sub itself has a 24db/octave drop-off but the cabin gain reduces that to only 12db/octave. My GUESS is that plugging the port would give you better response below 40hz at the expense of output in the 40-60Hz range. It's a total guess as I don't know the T/S params of the sub nor the enclosure volume in order to model it. Some might ask why did Tesla go this route? Well, the average listener probably thinks that 40-60Hz range IS deep bass just as they probably think Beats headphones sound great. In short, it's tuned for the masses and it's hard to fault them for that.

FWIW here is the RTA with the second to last EQ band set to +3.5 to try and fix that dip.
Screenshot_20210316-204343_AudioTool.jpg
 
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bpobill

Member
Feb 2, 2018
299
180
USA
Another thing you could try is plugging the port (along with polyfill). I've never been a fan of bass reflex enclosures in automotive environments. They have a 24db/octave roll-off while sealed enclosures roll off at 12db/octave. When you take into account the fact that cars typical have a cabin gain that is about 12db/octave starting at around 90-100 Hz you can see why sealed enclosures work quite well in them.

I have an SR+ but recently had an LR loaner so I took the opportunity to perform an RTA on the premium audio (EQ set flat, immersive sound off, fader center). The red line is what I have set as my 'reference' curve which is based on the one from Harman International; it's what I target when setting up an audio system.
View attachment 645951

Tesla did a pretty good job in tuning the system with the exception of that dip centered somewhere btw 3.5-4kHz (second to last EQ slider can help a bit but it seems to be centered around 2kHz unfortunately). As for the sub you can see about a 12db/octave drop off starting at around 40Hz. This is telling the the enclosure is most likely tuned to around 40-45Hz or so. The sub itself has a 24db/octave drop-off but the cabin gain reduces that to only 12db/octave. My GUESS is that plugging the port would give you better response below 40hz at the expense of output in the 40-60Hz range. It's a total guess as I don't know the T/S params of the sub nor the enclosure volume in order to model it. Some might ask why did Tesla go this route? Well, the average listener probably thinks that 40-60Hz range IS deep bass just as they probably think Beats headphones sound great. In short, it's tuned for the masses and it's hard to fault them for that.

FWIW here is the RTA with the second to last EQ band set to +3.5 to try and fix that dip.
View attachment 645959
I love my beats headphones. Not everyone listens to smooth jazz while drinking a Manhattan.

in all seriousness everyone has different tastes in music and how their music sounds. I did car audio for a few years back in the day. Some people liked jazz or classical and focused more on highs and mid range. Some people listened to hip hop and wanted to rattle their cars apart. I’m personally in the middle but lean towards more bass. Stock system sounds good but I do want more bass from it, especially down low. But I do like my beats studios. Wonderful bass and decent noise cancellation.
 

webwarmiller

Member
Feb 4, 2021
26
27
dallas, tx
I love my beats headphones. Not everyone listens to smooth jazz while drinking a Manhattan.

in all seriousness everyone has different tastes in music and how their music sounds. I did car audio for a few years back in the day. Some people liked jazz or classical and focused more on highs and mid range. Some people listened to hip hop and wanted to rattle their cars apart. I’m personally in the middle but lean towards more bass. Stock system sounds good but I do want more bass from it, especially down low. But I do like my beats studios. Wonderful bass and decent noise cancellation.
Perhaps I should have said Bose instead :). Notice that the reference curve includes an increase in bass that starts at around 160 hz and increases to about a +9dB boost from 50 and down. This curve is one that will appeal to the masses with enhanced bass and gradual roll off of higher frequencies to prevent ear fatigue. It is not a FLAT reference by any means.

I've never understood the idea of different EQ settings based on the style of music. When any given album/song is mixed/mastered it has already taken into account that genre's desired sound. EDM/rap/hip hop are already mixed with an exaggerated low end. IMO a properly tuned system will sound good with all forms of music including spoken word. Once I've tuned a system I never touch the EQ again. Thinking one needs different eqs settings based on the style of music is akin to thinking one needs different types of vision filters based on the style of artwork they are viewing.
 

leonar40

Member
Jan 6, 2021
189
98
Bloomington, IN
Just to close the loop on this thread (since it went way off topic), tonight I removed all the Polyfil from the subwoofer, back through the port hole. I used a drain snake, the kind with a brush on the end, and that worked very well! With the Polyfil removed the subwoofer returned to normal volume. It's actually pretty good for mid-bass fill. Just missing that smack you in the back feeling that I like. :)
 

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