How to Improve OE Sub Bass Quality and Eliminate Vibrations

[foywilliamd]

@89 and 95 can you provide links to the amp and subs you are running now? And maybe pictures of your interior? Thanks in advance!

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[METAL]

MKV Owners:

Have any of you upgraded the factory JBL sound system in the 2020/2021 Supra?

After porting the factory box and adding acoustic foam and dynamat, I am still not pleased with the low range bass response.

I’ve seen many mixed reviews about the performance of the Bavsound Ghost subwoofers. Some people love them, some people say they don’t sound much different.

I think it has a lot to do with the factory amplifier.

Considering replacing the amp (suggestions?) as well as the subwoofers with something like the Rockford Fosgate P3SD4-8, which is a shallow-mount subwoofer. Though, I don’t think it will fit into the OEM subwoofer box without modifications (it is still too deep). I’d like to maintain an interior look as close to stock as possible, as trunk space is already limited, and this is my daily driver. This means an additional sub and box is out of the question.

Adding links to the modifications I’ve made so far, as well as to the subwoofers mentioned above.

https://www.bavsound.com/products/ghost-subwoofer-upgrade-for-toyota-supra

https://www.crutchfield.com/p_575P3SD48/Rockford-Fosgate-P3SD4-8.html?cc=02&tp=111

https://www.supramkv.com/threads/how-to-improve-oe-sub-bass-quality-and-eliminate-vibrations.5092/

Thoughts?

Whats your budget?

 

[METAL]

Check with inMobile on specifics. Interior is oem (amp is hidden). Only visual difference is the gain dial for the sub, which is below steering wheel.

Little vague.

Here is my build for more transparency.

https://www.supramkv.com/threads/audio-build-journal-mobridge-focal.9862/

 

[foywilliamd]

Update for all - I think the Rockford Fosgate P3SD4-8 Shallow Mount 8” subwoofers

Whats your budget?

Budget is ideally $1500 or less. I think I’m going to proceed with the two RF subs mentioned before with a 500W amp. I’ll keep the forum posted on results either way.

 

[METAL]

Update for all - I think the Rockford Fosgate P3SD4-8 Shallow Mount 8” subwoofers

Budget is ideally $1500 or less. I think I’m going to proceed with the two RF subs mentioned before with a 500W amp. I’ll keep the forum posted on results either way.

What do you plan to run those subs at Frequency wise? Keep in mind the oem subs are playing mid bass and sub bass.

 

[foywilliamd]

What do you plan to run those subs at Frequency wise? Keep in mind the oem subs are playing mid bass and sub bass.

Honestly I’m not sure. There are some highly rated audio shops in town, I was planning to have them do the majority of the work. Do you have recommendations?

 

[METAL]

Honestly I’m not sure. There are some highly rated audio shops in town, I was planning to have them do the majority of the work. Do you have recommendations?

The concern here is by deleting the oem subs you are removing a chunk of the frequency band that the cabin speakers do not play. Asking an aftermarket sub to replace those frequencies is a tall ask and will not sound good. Best option is to leave those oem subs alone and add a sub in the trunk.

 

[nosavingthrow]

For the speaker wadding, cut with the template: which side goes up/down? Like it gets folded into a box shape, do you leave the top open, or bottom open once you get it into the enclosure?

 

[tadda]

For the speaker wadding, cut with the template: which side goes up/down? Like it gets folded into a box shape, do you leave the top open, or bottom open once you get it into the enclosure?

fold such that top is open....

 

[spta97]

fold such that top is open....

Doh! Me and g/f did this mod today and put the wadding in the wrong way!

It didn't make sense to me as I figured the port from the sub would be blocked but guess I read the directions wrong.

I wish I had read this post or further back as I just now read through every page.

We'll fix tomorrow, but in the mean time it made a huge improvement!

Wanted to say thanks Tadda! Awesome job and awesome write up!

 

[tadda]

Doh! Me and g/f did this mod today and put the wadding in the wrong way!

It didn't make sense to me as I figured the port from the sub would be blocked but guess I read the directions wrong.

I wish I had read this post or further back as I just now read through every page.

We'll fix tomorrow, but in the mean time it made a huge improvement!

Wanted to say thanks Tadda! Awesome job and awesome write up!

This pic might help clarify things...As you can see with the sub removed there is actually a top port and a side port ..you don't want to block either with the wadding.....

 

[spta97]

This pic might help clarify things...As you can see with the sub removed there is actually a top port and a side port ..you don't want to block either with the wadding.....

Thanks Tom - yes, that is how I figured it should be done (after doing it incorrectly lol).

Today we'll switch around the batting and tackle some of the other sound deadening (like the back piece).

Only part I'm missing is the self adhesive foam to block the underside of the (now ported) trim piece.

2 other questions if you don't mind:
1. Did you stick the foam strips to the trunk or to the trim piece?
2. I recall reading you used 1/4" thick (high) foam, would 1/2" or larger be too much? I have 3/16" at home and need to get thicker but would have more use for the 1/2" - 3/4".

2 other thing to add to the thread:
- I know a lot of people use Dynomat, but I have had extremely good luck with Peal and Seal for sound deadening (I have done my share of car audio) - it's about $20 for the roll.

It is a roofing material with foil on one side and tar on the other. When using, I clean the panel with denatured alcohol, stick on the Peal and Seal, then heat it up with a heat gun and press it down with leather gloved hands.

It works wonders (just as well as any sound deadening from what I have read) and will not peal off if applied with a heat gun (even without a heat gun it is very difficult).

It also works well for it's intended use

- Although not the same vehicle, my X3MC has ID6 and the HK Audio. Below is my thread on adding an amp/sub which may help some people get pointed in the right direction if looking to add a sub: My Sub/Amp Install on my BMW X3MC

 

[tadda]

@spta97

My concern with using the "peal and seal" would be with respect to odor and outgassing...This may be fine to use in a sealed trunk area, but the Supra has an open hatch area and the odor will be much more noticeable...

 

[spta97]

@spta97

My concern with using the "peal and seal" would be with respect to odor and outgassing...This may be fine to use in a sealed trunk area, but the Supra has an open hatch area and the odor will be much more noticeable...

I used it in my X3MC (hatch, not trunk) and have not ever experienced any odor.

Initially I was concerned it would smell like a freshly paved driveway on hot summer days when used in my previous E46 M3 (trunk) but there is no odor at all which I could smell. Same is true for the X3MC which has a hatch as stated.

That's not to say there isn't something there at a chemical level, just nothing I have ever noticed or experienced.

 

[tadda]

FYI...

Just applied adhesive backed felt tape to a number of places around the edges of the plastic rear hatch brake light cover and contacting hatch surfaces....There was a good amount of vibration coming from this plastic cover, particularly obvious during very low bass notes...Vibration from this area has been eliminated...

Felt Tape in Self Adhesive

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