How to Improve OE Sub Bass Quality and Eliminate Vibrations

pav911

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Hi Folks.

Picked up my 2020 Pro UK car with the JBL system yesterday and straightaway noticed the lack of low down bass and vibration from the sub enclosure (behind the passenger seat). Can i ask those of you that have modded your enclosures, did you give Toyota the opportunity to fix the vibrations? Did they try and fail?

I'm not sure how ready i am to start taking apart a brand new car.

Thx.
Pav.
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tadda

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Hi Folks.

Picked up my 2020 Pro UK car with the JBL system yesterday and straightaway noticed the lack of low down bass and vibration from the sub enclosure (behind the passenger seat). Can i ask those of you that have modded your enclosures, did you give Toyota the opportunity to fix the vibrations? Did they try and fail?

I'm not sure how ready i am to start taking apart a brand new car.

Thx.
Pav.
The issue is a fundamental design flaw where a narrow rear cover panel was placed directly over the existing bass exhaust ports that causes these vibrations and reduced bass response to occur...Toyota currently does not have a proper fix for this...

All you really need to do is modify the narrow rear cover panel and add some insulation as shown below....

subwoofer 2a narrow rear panel.jpg


ported subs air flow.jpg


subwoofer 7b ported rear panel.jpg
 

pav911

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Seems like just taking the rear cover panel off and letting the existing ports breathe will be an improvement. I'll start with that until i feel braver.

Thx Tadda..
 
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tadda

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Seems like just taking the rear cover panel off and letting the existing ports breathe will be an improvement. I'll start with that until i feel braver.

Thx Tadda..
Yes, that would be a very good first step although not very aesthetically pleasing to see...Adding a port to the narrow rear panel and some additional foam insulation solves the problem and also looks good in appearance...

good luck :thumbsup:
 

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Seems like just taking the rear cover panel off and letting the existing ports breathe will be an improvement. I'll start with that until i feel braver.

Thx Tadda..
Hi Pav, your Supra being Euro will have an even quieter exhaust than the factory Kiwi one which is way quieter than the US one.

This means that you will hear everything going on with the stereo in the car while driving.

I have done Tada's mods, it makes a a noticeable difference & is well worth doing.

Having said that now I have a Boost Logic exhaust it isn't as obvious when driving, nor are the amazing intake noises from the MST intake.

Make sure you get Bimmer code, if you haven't already, to remove the fake engine noise through the speakers, brighten the screen etc,
 

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Does the speaker batting material have to be in a sheet? Does stuffing loose poly batting cause issues?
 
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tadda

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Does the speaker batting material have to be in a sheet? Does stuffing loose poly batting cause issues?
Actually 1/2" sheets are preferred for this application as you'll want to line the walls of the enclosure and be careful not pack the enclosure as this could reduce overall volume...that said, you could try packing loosely to see how this effects the bass response....
 

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There is one more area that requires insulation in the rear cargo area that is also a major contributor to harsh vibrations experienced during low bass tracks and that is the rear cargo panel...Behind the cargo panel there is quite a bit of open dead space and the plastic panel does not have any insulation between that and the body...

I used the 2" foam padding I purchased for the narrow rear sub cover panel and applied foam to the following areas shown below...The rear cargo panel is easily removed..I also opened the empty compartment that is used to store the roadside triangle that US Supra's don't have and inserted a 2" foam strip...

No more vibrations or rattles...

Rear Cargo Panel Insulation.jpg
Thanks for the awesome guide. Might be a stupid question, but what steps did you take after removing the 2 plastic nails to remove that plastic rear cargo panel?
 
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tadda

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Thanks for the awesome guide. Might be a stupid question, but what steps did you take after removing the 2 plastic nails to remove that plastic rear cargo panel?
Here are instructions on how to remove that rear panel....

Amp panel a1.jpg

Amp panel a2.jpg
 
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A member in our Supra Facebook Group just posted this video below outlining the steps done in this thread...

***Edit: Applying RTV to the sub grill cover in this video was done incorrectly...RTV should be applied between the 12 spoke cover and flat grill plate....Read my original post to read how this is done correctly***

 
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pav911

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@tadda, in the video above the silicon is applied to the circular grill plate. so it'll end up going onto the carpeted sub enclosure when you put the grill back on. am I right in thinking I need to put it in between that circular grill plate and the spoke part of the grill cover? thx

Edit: I can't figure out how to do this - "separate the 12 spoke grill cover from the flat grill plate"
 
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tadda

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@tadda, in the video above the silicon is applied to the circular grill plate. so it'll end up going onto the carpeted sub enclosure when you put the grill back on. am I right in thinking I need to put it in between that circular grill plate and the spoke part of the grill cover? thx
Yes, I saw that...And yes, it was done incorrectly.... I sent him a message telling the author of that video about this....

You are correct that after removing grill cover assembly you need to separate the 12 spoke cover from the grill plate and apply small dollops of RTV between 12 spoke cover and grill plate in areas I show in diagram below...

woofer grill cover felt pads.jpg
 

pav911

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I just don't see how I can separate the cover any more without breaking it.
 
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tadda

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I just don't see how I can separate the cover any more without breaking it.
After removing the Subwoofer top grill assembly from the subwoofer top cover simply go around and gently pry up to separate the 12 spoke cover from the flat grill plate...it's actually very easy to separate...

Protip: With 2 fingers try gently depressing the A-clip as you push the flat grill plate past the clip....
 
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pav911

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