A90 Subwoofer - Any And All Info Pertaining To Subs

[30MilesOffshore]

Thought I would start a thread discussing only the subs. The other thread has too many pages and stuff is getting buried and mixed in. So chime in on anything you want to discuss about them.

I spent all day messing around with them and thought I would share my findings. Since there isn't a How To Remove Subwoofer section yet, I'll get started with that first. This probably isn't 100% correct but it worked for me. It was more of a pain to reinstall everything than it was to take it apart.

------------------------------------------

How To Remove Subs:

• Remove the trunk security shade (#2).

• Remove the battery cover panel (#1).

-----------------------------------------

You will now be able to see the plastic clip holding the subwoofer trim board on. To remove the plastic push pin (#1), you need to pry up on the center of the clip and pull the plunger high and then the trim ring will pop right out.

Now remove the sub panel board (#2) by pulling straight back towards the rear of the car. There are clips (#3) on both ends and also in the center which will simply pop out.

With the panel board removed you should now see another clip in the middle of the subwoofer baffle board that will need to be removed too. This is similar to the previous plastic push pin.

--------------------------------------

Remove Center Console

There are two T-20 screws located under the rubber mat that need to be removed (green circles). Once removed, you can pry straight up and the cup holder will pop out.

Next step is to make sure there aren't any screws in the cubby hole under the rubber mat. Mine did not have any installed but there are two holes there so double check. Once its clear, then pry straight up and it will pop out.

The manual shows two screws located in the center trim (yellow arrows) but I quadruple checked and could not find them at all. I could not see any place where the baffle board was connected to the center console so I did not have to do anything else. The two bolts (green) are only securing the center console down and do not have to be removed.

-------------------------------------

Rear Hatch Trim

There are 7 pieces of trim that will need to be removed. You want to start at the top and work your way down. All of the pieces lock into each other so there isn't any other way to do it that I could see.

-------------------------------------

Piece -1-

This is held in by a few white plastic clips and will simply pry out. Be sure to pull horizontally towards the middle of the car and they will pop out.

------------------------------------

Piece -2-

Using a Torx T-50 bit you will need to unbolt the transverse bar and seatbelt (red circles). There are also two T-20 screws that will need to be undone (green circles).

Now just like piece -1-, pull horizontally towards the middle of the car. Be sure to be delicate around the seatbelt area. The trim is split to allow the seatbelt to feed through and there is a clip located right behind the split.

Once removed, you can remove the trim piece right above it. I forgot to label it but it is about the size of a cell phone and attached to the roof of the car. The bottom will pry out first and then pull it straight down to release the top section.

----------------------------------

Piece -3-

Transverse pipe has one Torx screw located on each end. Using a T-50 bit just unbolt it and it will pop out. I would go ahead and remove the seatbelts at this time to since it's also a T-50 bit.

---------------------------------

Piece -4-

Remove the door sill cover by pulling straight up towards the roof of the car. There are 4 plastic white clips and one peg at the end that locks into piece -6-

-----------------------------------

Piece -5-

This one is tricky! You have to maneuver this piece in two different directions.

But first you will need to unbolt the transverse bar and seatbelt (red circles). These should have already been done in Piece -3- removal. There are also two T-20 screws that will need to be undone (green circles).

There are 3 large clips located behind the speakers (red circle). This part of the trim will need to be pulled towards the front of the car.

The lower part of the trim is attached in two sections. One section has right angle clips and attach to the sub baffle board (green circle). This will need to be pulled straight up about an inch and then towards the front of the car.

The very bottom has several clips (yellow circle) that attach to piece -6-. These clips are all inserted vertically and will just pull straight up towards the roof of the car.

More pictures to help....................

-------------------------------------

Rear Tower Speaker Removal

You now have access to the rear tower speakers. The are held in the by three T-20 screws (yellow circles). You can unplug the speaker (yellow arrow) by pulling straight out. You do not need to disconnect the other wire.

• BTW, the speakers are Harman Kardon. The door speaker grill is stamped JBL and the sound system is advertised as JBL but all of the rear speakers are HK. However, both JBL and Harman Kardon are owned by Harman International which is owned by Samsung.

-----------------------------------

Piece -6-

This has a 10mm plastic nut (red circle) that will need to be removed. You will also need to remove one white plastic clip from the door sill area (green circle). There are also three right angle clips (yellow circles) that attach it to the baffle board. To remove you will need to pull up about an inch and then out towards the front of the car.

--------------------------------

Piece -7- Subwoofer Baffle

I tried prying at the very bottom section below the baby seat attachment. I ended up snapping a clip as I found out that the clips actually slide down to lock in place instead of pulling out towards the front of the car. The sliding locks are similar to sliding a gun into a holster.

First step was to pry straight up on the flat deck around the subwoofer grills. There are several clips (yellow arrows) that will pop right off if you pull straight up towards the roof.

Next step was to slide the entire baffle straight up towards the roof. Do not pull towards the front of the car. The entire baffle will slide up towards the transverse bar (red arrow). When you slide the baffle back down the clips will slide into the locks.

If you look by the center console, you will see that the baffle also slides straight up in this area too (green arrow).

------------------------------------

Sub Removal

I did not remove the entire baffle, I simply slid it high enough to give me access to the subs. I used a bungie cord to hold it up while I worked on the subs.

First you need to unplug the speaker connection (yellow circle). Then there are two clips (yellow circles) holding the speaker wire down that will need to be pried off too.

Now you can unbolt the four nuts (red arrows) that lock the subwoofer in place. They are located on all four corners. At this point you are done with the sub removal.

Sponsored

 

[30MilesOffshore]

What I found out about the subs:

• The subs are Harman Kardon. The model number, build date, and BMW Part number is listed on the orange decal. So if your looking for an OE replacement, you can simply shop around using the BMW Part number. Odds are this will be cheaper than someone advertising it as a Supra Subwoofer.

 

[30MilesOffshore]

More sub facts:

• The bottom of the subwoofer enclosure is open. There is a strip of green tubing that goes around the outside edge. This tubing gets compressed when you place the speaker down on the sheet metal of the car. This compression gives you an air tight seal.

Some people have mentioned rattling or air leakage so I would think this would be a good place to check. I have not experienced any rattling but I did notice that one of the installation nuts on the corner was not torqued down all the way. It felt as if it was just hand tightened. So double check yours.

 

[30MilesOffshore]

Sub info:

• These are 8 Ohm subs. I measured 7.3 on one and 7.5 on the other. I would assume that they are wired in Parallel to give the system an effective 4 Ohm load.

 

[30MilesOffshore]

Subs Stuff:

Effectively the subs are ported and use the sheet metal chamber as the port. The air is pushed down from the bottom of the sub through the large opening in the sub box (red arrow). The air then goes into the elongated chamber (yellow bar) and then is vented out of the three oval holes (green arrow).

 

[30MilesOffshore]

Sound Check 1:

I ran a few tests to see what kind of results I would get. I originally wanted to stuff the subwoofer box with polyfill to try to adjust the "Q" Factor. But this could not be done due to the large hole in the bottom of the subwoofer box. So I compromised and decided to fill the port chamber instead. Given the confined space and access issues, I stuffed the sheet metal chamber with micro fiber towels instead of polyfill. The towels made it easier for me to remove after the test (neon towels in the chamber).

I played 3 different types of music (jazz, hip hop, and rock). I didn't adjust the EQ, Tone, Sub or any other parameters. I left everything the same. This was time consuming but I played one song with the chamber not stuffed and then stuffed the chamber and listened immediately to the same song. I repeated this three times for each song so I could get a good comparison going.

Result: I could not tell any acoustical difference with the towels in there. Overall I felt that everything sounded the same as before. However, there were a few times when I felt that the volume level was dampened a little bit and not as loud. It sounded like I had turned it down about 10%.

Discovery: By stuffing the sheet metal chamber with micro fiber towels, I realized that the entire chamber is completely open. There are holes on the edges and also in the metal itself where air can flow freely in/out. In hindsight as I type this, the other thing I realized was that I couldn't tell if there was a divider section in the middle. If there isn't a divider in the middle, then the air pressure/air flow from one sub will interact with the other sub. I'm guessing this has a chance to cause some pressure/phasing/cancellation issues. More tests will need to be done to confirm if this is happening.

 

[30MilesOffshore]

Sound Check #2:

Ported vs Sealed? After the damping Test #1, I wanted to see what would happen if the subwoofer box was sealed. I decided to block off the open port directly below the subwoofer housing. I used multiple layers of painters tape in a cross weave pattern to accomplish this. By using the tape, it layed flat and the green compression gasket from the subwoofer housing was still able to compress and make a tight seal. I also left the micro fiber towels in the the chamber from Test #1.

Result: It sounded bad! You could definitely tell the subs were being strangled and starving for air. The volume level of the bass was completely lowered by about 80%. It only took one song to realize that the sub setup definitely needs the ports to run efficiently.

 

[30MilesOffshore]

Sound Dampening / Foam:

A few people have mentioned rattles/vibrations from the back area. I have not experienced this but I was ready to lay some down where I thought it might be needed. I had several sheets of sound dampening pads, tesa tape, and jute material ready to go.

As I took everything apart I could not find any spots that felt like they needed any extra damping. Everything locks into place tightly and the majority of plastic trim already had either dynamat on it or acoustical foam/jute material installed. The subwoofer baffle board had jute material already installed and there was even foam above the subwoofers to give a tight seal.

I had considered putting some on the sheet metal port chamber but all of the areas are really small and would end up just putting a square inch or two on it. Overall, I didn't install any sound deadening at all. I didn't see any spots that needed it and I don't have any rattle or vibration issues that I needed to take care of.

If your car is having issues then just try to pinpoint them and apply the appropriate material where necessary. You have several options to choose from. As @tadda, said "it can be like a game of whack-a-mole". When you fix one rattle another can show up until you find them all.

 

[SA91]

Do you intend on replacing the subwoofers or are you just exploring?

 

[30MilesOffshore]

Do you intend on replacing the subwoofers or are you just exploring?

I was just exploring, as I'm not 100% satisfied with the sub sound. My previous sound comparison was the M4 and that sounded amazing when compared to this system. Since they're both essentially BMW products, I was expecting the same result as the M4. It is definitely a night/day difference between the two systems.

So I wanted to see how this was setup, and to see if there was anything that could be tweaked to improve the sound quality. I'm open to the idea of replacing them but I'm not actively looking to do that yet. I was hoping others would chime in with ideas, tips, insight, or other brainstorming ideas.

One thought I have is that the amplifier seems under powered for this system. For comparison, I would rarely have to turn the volume up past 50% on the M4, and on the A90 I have to turn it up to 75% to achieve the same volume level. I'm not sure if it's possible, but I was thinking there is a chance that the amplifier from another BMW might be able to be swapped out (simple plug & play). Does anyone have any insight into this?

 

[30MilesOffshore]

Sound Check #3:

Keep in mind that this test and all the others above are primitive sound checks but they are still good for basic testing. Next test was to see how the subs sounded with strictly bass notes playing and no other input. I didn't adjust any of the EQ or sound settings. I left all the settings the same as I would when I play my daily music. I played several different low end frequencies and a couple of other basic sound checks:

• 30hz, 40hz, 50hz, 60hz, 70hz, 80hz, 90hz, 99hz
• Left Channel + Right Channel Check
• In Phase + Out Of Phase Check

All of these were loaded up and played from the USB Drive in the center console. These are old school test notes from back in the day (2001) so the compression is not the best (MP3 @128kbps). However, it is good enough to still get some ideas of what the system can or can't do.

I have attached them below if you wanted to give them a play and have some fun with your system. I would recommend playing on another system first (computer or home system) to get an idea of what they sound like (especially the In/Out Phase Check). *Warning* these are bass notes only so don't crank your system up too loud because you increase the risk of blowing other speakers that aren't designed to play those frequencies (mids & tweeters).

Results:
Bass Notes: All of the bass notes sounded good. The subs actually did a decent job at playing each frequency. I did notice that 60hz had the most resonance in the car. The bass was crisp, clean and punchy. They sounded just like I would have expected them to sound. The muddiness factor that drives me crazy was completely gone. They definitely don't sound that way when I'm playing my regular daily music.

Left/Right Check: It sounded fine and seemed balanced to my ears.

In Phase/Out Phase Check: Both tests (In & Out) sounded exactly the same when I ran this test. I could not tell any difference between the two tests.

Thoughts:
The bass notes are clear when played alone and muddy when played with my daily music. This leads me to believe the subs are not getting a clean signal when played with daily music. They are getting low end frequencies, and alot of midrange frequencies as well. This is probably contributing to the muddiness factor that I'm hearing. Better filtering to clean up the subwoofer signal would definitely fix this problem. This could be done with a 8-Ohm Low Pass 80hz Filter but the cheapest fix would be to try to tweak my EQ settings to see if I can get a cleaner sound.

With the phase check the (In Phase) should arrive at your ears at the same time and sound balanced. The sound should sound like it's all around you and you are sitting in the middle. The (Out Phase) should sound like it's coming from another location or direction. It will sound like someone is talking to you off to the side. The cheapest and first place to try to fix this is with the EQ settings to see if I can clean it up.

I thought I had the EQ setup to my liking, but since both tests above suggest otherwise, it looks like it's time to mess around with the settings a little more and see what can or can't get cleaned up.

 

[Kaizen]

This is fantastic! Thanks for dissecting all of this. Can't wait to see what you do to get this thing sounding a lot better.

 

[JasonO]

Sound Check #3:

Keep in mind that this test and all the others above are primitive sound checks but they are still good for basic testing. Next test was to see how the subs sounded with strictly bass notes playing and no other input. I didn't adjust any of the EQ or sound settings. I left all the settings the same as I would when I play my daily music. I played several different low end frequencies and a couple of other basic sound checks:

• 30hz, 40hz, 50hz, 60hz, 70hz, 80hz, 90hz, 99hz
• Left Channel + Right Channel Check
• In Phase + Out Of Phase Check

All of these were loaded up and played from the USB Drive in the center console. These are old school test notes from back in the day (2001) so the compression is not the best (MP3 @128kbps). However, it is good enough to still get some ideas of what the system can or can't do.

I have attached them below if you wanted to give them a play and have some fun with your system. I would recommend playing on another system first (computer or home system) to get an idea of what they sound like (especially the In/Out Phase Check). *Warning* these are bass notes only so don't crank your system up too loud because you increase the risk of blowing other speakers that aren't designed to play those frequencies (mids & tweeters).

Results:
Bass Notes: All of the bass notes sounded good. The subs actually did a decent job at playing each frequency. I did notice that 60hz had the most resonance in the car. The bass was crisp, clean and punchy. They sounded just like I would have expected them to sound. The muddiness factor that drives me crazy was completely gone. They definitely don't sound that way when I'm playing my regular daily music.

Left/Right Check: It sounded fine and seemed balanced to my ears.

In Phase/Out Phase Check: Both tests (In & Out) sounded exactly the same when I ran this test. I could not tell any difference between the two tests.

Thoughts:
The bass notes are clear when played alone and muddy when played with my daily music. This leads me to believe the subs are not getting a clean signal when played with daily music. They are getting low end frequencies, and alot of midrange frequencies as well. This is probably contributing to the muddiness factor that I'm hearing. Better filtering to clean up the subwoofer signal would definitely fix this problem. This could be done with a 4-Ohm Low Pass 80hz Filter but the cheapest fix would be to try to tweak my EQ settings to see if I can get a cleaner sound.

With the phase check the (In Phase) should arrive at your ears at the same time and sound balanced. The sound should sound like it's all around you and you are sitting in the middle. The (Out Phase) should sound like it's coming from another location or direction. It will sound like someone is talking to you off to the side. The cheapest and first place to try to fix this is with the EQ settings to see if I can clean it up.

I thought I had the EQ setup to my liking, but since both tests above suggest otherwise, it looks like it's time to mess around with the settings a little more and see what can or can't get cleaned up.

Great breakdown. I was thinking of doing one but I start tearing it apart and I think how much additional work it would be and just plug away instead. Glad your more disciplined than me.

I think some of the mud is from the amp and 4” speakers. I don’t think the factory amp has a good power section as it couldn’t feed everything well.

Once I added an amp and replaced the subs, my mids got significantly better. High volumes still suck as the mids get lost in road noise and mud. If I had to guess, that has more to do with high efficiency 4” speakers being fed full range or damn near full range signal along with needing some quality CLD installed than the amp at that point.

My next step is to turn off the amp and run some sweeps to see where the mids are picking up. Once I do that, then I’ll decide what to do next. The sub channel appears to be crossed over below 180Hz.

 

[Hakkim23]

Finally someone made an aftermarket subwoofer!
Hell yes!

 

[tadda]

How to Improve OE Subwoofer Quality and Eliminate Vibrations

I spent a fair amount of time over the past few weeks thinking about how to improve the Supra's subwoofers, which we all know by now, were not designed properly and as a result have issues when it comes to both vibrational noise and lower bass quality...

Some improvement to the bass response can be made by removing the Active Sound Design (faux engine / exhaust noise) which is electrically imposed onto the bass signal when sport mode is selected ...I found that the ASD feature actually "muddies" the bass response and increases distortion and noise...

Also many of us have played with EQ settings in an attempt to optimize sound quality but the OE system still fell somewhat short...I also found that selecting the "surround" enhancement feature added to the phase distortion which resulted in reduced sound clarity...This is one of the first things I turned off and the system clarity was noticeably improved...

Here are my current audio settings:

• ASD / Active Sound Design (off - using Bimmercode)
• Surround (off)
• Speed Volume (+4)
• Balance: (0)
• Fade: (front +2)
• Broad Bass (+2)
• Broad Treble (-2)
• Equalizer (shown below)

These are my new EQ settings (below) after improvements made to current OE Subwoofer system...I can also now raise the volume to 2/3 of max with no low bass distortions or vibrational noise...

With respect to the OE subs I saw a few areas for improvement after seeing a few pics posted of stripped down rear cargo areas and began to get to work...

I lined the walls of both metal sub enclosures (which are indeed separated) with 1" speaker wadding to improve lower bass response and bass quality by reducing distortions created by destructive waves within the metal enclosure..The wadding also serves to increase it's "effective" volume...Speaker wadding turned out to be a very good solution for this...

Enclosure Lining - Wadding Template (left side) / flip over for right side...I was actually able to roll up the speaker batting cut from a template (shown below) and slip it through one of the elongated exhaust ports and then use a long screw driver to manipulate the cut batting to line the walls of the metal enclosure shown below:

Most of the lower bass vibrational noise and distortion are actually due to the narrow rear cover panel which blocks most of the woofer exhaust energy and introduces most of the nasty low freq vibrations heard...The solution here was to insulate the area within the narrow rear panel with 2" foam leaving the exhaust port open and then add 2" exhaust ports to the narrow rear panel...

Foam Cutout Dimensions (below):

Note: I didn't need to remove the narrow rear panel mounting brackets...I actually used a 4"h length of 2" foam and cut slits into the foam such that the foam could be worked in from the top behind each of the brackets...

I also added a 2"h x3"d foam strip in the center and (2) 1"h x 1"w foam strips on either side above exhaust ports, under the top cover, to fill some voids as shown in pic below...

View attachment 25647

Installing Rear Panel Exhaust Ports...

1. Cover the front carpeted area of narrow rear panel to be cut with tape and mark a 2" diameter circle
2. Use a dremel tool with disk to rough cut out the plastic panel within the marked circle
3. Use a small dremel grinding drum to finish the edges of the port hole
4. Cut the black OE panel insulation in the the center of hole and fold back on either side
5. Insert 2" exhaust port
6. Use tie wrap to hold thin black OE panel insulation along side walls of exhaust port
7. Secure port to rear panel with drops of epoxy at edges touching rear panel and port walls

I also placed black metal speaker mesh (4" x 4") over the three elongated holes and secured in place with 3m tape...

View attachment 25775

I've also identified another area that needed to be addressed...I discovered this after implementing all these other improvements, thus allowing me to significantly increase volume along with raising bass EQ settings...What I found was that there was some exhaust port energy escaping from under the long narrow rear panel (which as I show in a few pics below) causing the rear floor panel to vibrate...Keep in mind that this is yet another design problem which causes the floor panel to vibrate where in-turn this vibrational energy is transferred to the cargo areas' side and back panels causing them to vibrate as well...

The solution here was to apply some adhesive back foam to the areas show below which eliminated any energy transfer under the rear cargo floor panel...

Below I first applied 1.5"d x 4" L x 0.25" h adhesive backed foam strips above and below the exhaust port to isolate them further from the top cover and floor....

Next, the image below shows where some exhaust energy from the 3 elongated ports was also being released under the large rear floor panel causing it to vibrate greatly...With the floor panel removed simply place your hand under the narrow panel and you'll see / feel the exposed gap ...

Shown below are the locations where 2 adhesive back foam strips were applied to underside of exposed narrow rear panel ...The left adhesive backed foam strip was 1.5"D x 11" L x 0.25" H and the right foam strip is 1.5"D x 6" L x 0.25" H...This essentially sealed off the gap where the exhaust energy was also be channeled...

As a result the large rear floor panel vibration has pretty much been eliminated and side and rear trunk panels no longer vibrate during low bass / high volume music passages....

As far as materials, I used Noico RED 315 mil Sound Insulation , which I already had available for beginning my next project of eliminating front door speaker vibrations ....

Shown below is a pic of the finished project:

Here is yet another area that required attention for eliminating subwoofer grill rattle / vibrations...I did this awhile ago and thought it might be helpful to post while we're on this topic....

Apply small dollops of flexible silicone adhesive (red dots shown below) between grill insert plate and grill cover...

And finally, I found that the rear cargo panel was also a major contributor to harsh vibrations experienced during low bass tracks ...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 for the narrow rear sub cover panel and applied it 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...

I'm extremely pleased with the results...Bass response is noticeably lower and punchier and vibrational noise is gone...I can now listen to the sound system at 3/4 volume and the bass kicks ass!

---------------------------------------------------------------------------------------------------------------------------------------------------------------

Project cost: $30

Here is a list of materials:

2" Foam Pad

1" Speaker Wadding

2" Exhaust Port

Sponsored