How to Improve OE Sub Bass Quality and Eliminate Vibrations

[spta97]

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

Thanks for posting! Very timely as I am getting some vibration from this area as well.

I also seem to be getting a vibration from inside the woofer enclosure itself. At first I thought it was the ports, but I removed the entire piece and it persisted.

There also seems to be some sort of resonance behind the passenger seat.

More work to do on this...

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[tadda]

Thanks for posting! Very timely as I am getting some vibration from this area as well.

I also seem to be getting a vibration from inside the woofer enclosure itself. At first I thought it was the ports, but I removed the entire piece and it persisted.

There also seems to be some sort of resonance behind the passenger seat.

More work to do on this...

Did you also apply silicone adhesive between the woofer grill and cover plate as I mention in my 1st post? ..Those had quite a bit of vibration until the 2 plates were isolated from one another using that adhesive....

I also stuffed quite a bit of foam in the empty cavities within the subwoofer cover itself...

 

[spta97]

Did you also apply silicone adhesive between the woofer grill and cover plate as I mention in my 1st post? ..Those had quite a bit of vibration until the 2 plates were isolated from one another using that adhesive....

I also stuffed quite a bit of foam in the empty cavities within the subwoofer cover itself...

I actually removed the grills to take them out of the equation but will do that.

For the subwoofer enclosure, I was sticking my hand in it to see if I could find where it was coming from - will try the foam but it sounds (as best I can tell) like it is coming from the woofers or the plastic boxes the woofers are housed in.

I guess the true test would be to take it apart and just have the woofers in their enclosures.

I'm starting to think that this was not a design flaw, but rather a way for BWM/Toyota to avoid having to spend more on rattle avoidance.

It's amazing how much more bass this mod creates - rattles were not present in the stock config!

 

[tadda]

I'm starting to think that this was not a design flaw, but rather a way for BWM/Toyota to avoid having to spend more on rattle avoidance.

It's amazing how much more bass this mod creates - rattles were not present in the stock config!

It's interesting you say this because the very reason for adding exhaust ports on the narrow rear panel was to eliminate vibrational noise due to the panels being placed directly infront of the chassis exhaust ports restricting exhaust flow and in turn caused hellish vibrations and distortions!

These issues I find are like playing wack-a-mole....you resolve one major issue allowing you to increase volume and improve bass response and other problems surface...

I've finally gotten to the point I can increase volume to 3/4, significantly increase bass levels, and experience no vibrations or bass distortions...

Hang in there!

 

[spta97]

It's interesting you say this because the very reason for adding exhaust ports on the narrow rear panel was to eliminate vibrational noise due to the panels being placed directly infront of the chassis exhaust ports restricting exhaust flow and in turn caused hellish vibrations and distortions!

These issues I find are like playing wack-a-mole....you resolve one major issue allowing you to increase volume and improve bass response and other problems surface...

I've finally gotten to the point I can increase volume to 3/4, significantly increase bass levels, and experience no vibrations or bass distortions...

Hang in there!

Ha ha! That's so true.

It's also hard to actually locate where rattles are coming from - not to mention it is no party to be crammed in the hatch of this car during troubleshooting.

What is surprising to me is I did not have any of these issues with my X3MC install. Could it be because I jammed foam (egg crate) in anything that would take it after I used Peal and Seal on anything I could reach, or the W7 with a 500w JL amp just masks the rattles? Build quality seems similar between the two vehicles.

My biggest issue was the license plate rattling which I solved with more peal and seal and adhesive foam strips. Comparing these HK woofers (I have the same under my seats) to my W7 is like comparing the brightness of a candle to the sun.

I am starting to lean towards disassembly and foam jamming/peal and sealing everything but it seems silly for two OEM woofers...aaaaaand it's not my car lol.

 

[digicidal]

My biggest issue was the license plate rattling which I solved with more peal and seal and adhesive foam strips.

I initially had the same problem but solved it a different way... either one is cheap and easy though.

 

[nosavingthrow]

I did it! Thanks for the awesome guide and for answering questions. Definitely sounds noticeably better too.

Attaching some extra photos I took while progress:

 

[nosavingthrow]

Question about the dynamat on the trunk floor: it sounded like this reduced road noise (hurray!), but I am curious if it makes it harder to hear the stock exhaust?

 

[digicidal]

Question about the dynamat on the trunk floor: it sounded like this reduced road noise (hurray!), but I am curious if it makes it harder to hear the stock exhaust?

It should (slightly), but that can always be fixed by going with a louder exhaust. ?

 

[spta97]

I initially had the same problem but solved it a different way... either one is cheap and easy though.

I actually used this on the Supra. Nice simple plate holder but two issues why I didn’t use it on my X3MC:

1) The amount of vibration coming through the hatch was enough to rattle the metal in the plate itself.

2) I already had an ///M license plate frame which I like and I was concerned that people may not notice the other ~32 ///M badges BMW placed in/outside the vehicle and neglect to give me proper respect

 

[tadda]

Question about the dynamat on the trunk floor: it sounded like this reduced road noise (hurray!), but I am curious if it makes it harder to hear the stock exhaust?

I've used and found that with Dynamat you'll definitely experience less vibration and rattles. That said it seems to have had little to no impact on exhaust noise levels...

 

[GorillaGuy]

Hey Everybody,

I just wanted to share with everyone what I did to improve the bass in my MkV. Its not meant do be a DIY, just some pics and info on what I used and a brief description on how I did it.

I ended up removing the OEM subs and replacing them with some shallow mount 8" subs from Pioneer. I searched high and low for subs that had the shallowest profile and low cuFt requirements. I ended up coming across the 8" Pioneer TSA2000LD2 subs. Their profile was shallow enough to fit in the enclosures and only required 0.15-0.5 cuFt of space. I know these Pioneers aren't the greatest subs, but for me it was all about retaining the OEM enclosures and keeping everything looking OEM. I used a Kicker Key 500.1 amp to power them and tapped into the stock sub inputs for the signal.

The results are pretty good and sound way better than the stock subs. The lower range is drastically improved and the overall sub output is way louder. Here's a list of the major parts I used with some pics to summarize the install.

Parts:
Pioneer TSA2000LD2 Subwoofers (qty 2) - Pioneer Subs
Kicker Key 500.1 Amp - Kicker Key Sub Amp
Kicker 4 gauge Amp kit (46PK4) - Amp Kit
Kicker Bass knob (46CXARCT) - Bass Knob
12 gauge speaker wire - Speaker Wire
Install Gear 4/8/10 Distribution Blocks - Distribution Blocks
Rubber foam tape, 9/16" thick - Foam Sealing Strips
22 gauge wire for remote turn on
Lexan Board for amp mounting
Posi-taps
Add-a-fuse
Tessa Tape
Cable Ties

Install:
-Step 1-
Cut out OEM subs from the enclosure. I literally cut the fabric cone out and left the flange that mounts onto the box. This was the only way to maintain an air tight seal between the sub and the box.




-Step 2-
Using the thick rubber foam striping, line the flange where the OEM sub used to sit. This will allow for an airtight seal between the new sub and the enclosure box.




-Step 3-
Now here's the risky and somewhat "ghetto" part of this install.... For the perfectionists out there, this method probably isn't going to work for you, but I didn't have any other means to get it done. In order to get these Pioneer subs to fight into the oddly shaped enclosure, you're going to have to cut the sub mounting flanges into straight sections. I used an oscillating / reciprocating saw with a high quality metal cutting blade to get this done. It doesn't look pretty, but its not something you can see because their covered by the grilles. At the end of the day, it got the job done and that's all I cared about.




-Step 4-
I used 6 screws on each sub to mount them to the OEM box. You'll have to screw them in at a bit of an angle in order to catch onto that flange you cut out of the stock subs. After they're screwed in, I made sure they were air tight by pressing the bottom of the enclosure to a table (where the green seal is) and pressing on the sub. If their was resistance on the sub and no air leaking out of the circumference of the sub...youre good.




-Step5-
I wired these 2 ohm DVC subs in series, and then both subs in parallel at the amp which gives you an overall load of 2 ohms. The speaker wires were ran down the bottom of the enclosure and out of the ports where the actual bass comes out of. I tapped the stock sub wires with posi-taps and then ran everything over to the drivers side following the OEM harness. The distribution blocks linked above are where I made the connections between the subs and the output of the amp.






-Step6-
Mounted amp, distribution blocks, wiring, bass knob cable, etc to the Lexan board I cut. I mounted the board to a threaded post that was welded on the body of the car. I ran the power and ground cables to the battery, and 22 gauge remote turn on wire to rear passenger side fuse box (fuse 207). Fuse 207 is an extra unused fuse that turns off 5 seconds after you turn the engine off.





Like I said....this wasn't meant to be a total DIY. I wanted more to just share with you guys the general ideas I had to replace the stock subs with better ones while maintaining a totally OEM look. Maybe this will give others some insight on trying to do something similar with possibly different / better equipment or ideas. If anyone has any questions on how I did something and wanna try this for themselves....just send me a message and I can try to help you out.

 

[tadda]

^^ Nice job!

One suggestion...I think it would be a good idea to start a new thread in the Audio Section for this writeup for others to see and comment on your particular audio setup...

-------------------------
Side note:

And as I mentioned several times within this thread the Harmon Kardon OE subs are actually quite good and not really the problem here...In other studies done in the BMW forum by a few audio enthusiasts / professionals it was surprising to find in side by side comparative tests that the HK OE subwoofers actually performed much better than most shallow mount competitors!

I actually tried replacing the subs after modification with Bavsound Ghostsubs and was extremely disappointed and ended sending them back since there was really no major improvement in sound quality!

Bavsound Ghostsub Review: I really wanted to like them...

That said, I've always said that installing a dedicated amplified sub to the system, high pass crossovers to the existing HK woofers @ ~200hz (utilizing them as mid-bass woofers) would be the best low cost / high quality solution for the existing system...This would also effectively increase headroom of the HK OE amp as well since power below 200hz would no longer necessarily be drawn from the OE Amp...

This is my next step and will create a new thread when completed...

 

[tadda]

I did it! Thanks for the awesome guide and for answering questions. Definitely sounds noticeably better too.

Attaching some extra photos I took while progress:

nicely done!

 

[GorillaGuy]

^^ Nice job!

One suggestion...I think it would be a good idea to start a new thread in the Audio Section for this writeup for others to see and comment on your particular audio setup...

-------------------------
Side note:

And as I mentioned several times within this thread the Harmon Kardon OE subs are actually quite good and not really the problem here...In other studies done in the BMW forum by a few audio enthusiasts / professionals it was surprising to find in side by side comparative tests that the HK OE subwoofers actually performed much better than most shallow mount competitors!

I actually tried replacing the subs after modification with Bavsound Ghostsubs and was extremely disappointed and ended sending them back since there was really no major improvement in sound quality!

Bavsound Ghostsub Review: I really wanted to like them...

That said, I've always said that installing a dedicated amplified sub to the system, high pass crossovers to the existing HK woofers @ ~200hz (utilizing them as mid-bass woofers) would be the best low cost / high quality solution for the existing system...This would also effectively increase headroom of the HK OE amp as well since power below 200hz would no longer necessarily be drawn from the OE Amp...

This is my next step and will create a new thread when completed...

Id be curious to see how they compared with theses Pioneers.

I understand the OEM subs were specifically designed for the space and type of enclosures that are in the car. But they just seemed really cheap and flimsy. Like they wouldn’t withstand the extra power from adding an additional amplifier. The subs weighed barely anything, the cone material seemed extremely cheap, and the size/weight of the magnets was laughable.

I understand that a lot of the poor base response is due to the OEM amp, but I just didn’t trust the OEM subs would handle additional power from a dedicated sub amp. Your idea of adding an additional subwoofer and using a bandpass on the stock subs is prob the best route, but it wasn’t the route I wanted to take. I value whatever space I do have in the hatch and didn’t want to loose any of it. I also didn’t feel like spending $2500 on something like the Oem Audio Plus system which I’m sure sounds great. But for $600, I got what I was looking for, and I’m totally happy with it. The lower bass notes are now present and the sound quality has greatly improved. Plus I have confidence these subs will hold up over time and I won’t have to worry about replacing anything in the future.

Thanks for your detailed response to my post and all you have contributed to this forum. I’ve used lots of information you’ve provided on here a bunch of times and it’s highly appreciated.

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