[I800C0LLECT]

Just wanted to share an installer's post on the M3 he worked on as it relates directly to our G20. Bottom line, under seat mid-bass can be great. I have had several applications of that from custom installs. With the right approach everybody loves it. Simply put, infinite baffle is probably the easiest approach in our vehicles. See below...

View post on imgur.com

https://www.diymobileaudio.com/threa...1/post-5971390

Next up was the midbass install. Everyone knows that BMW has been installing their 8" midbass drivers under the driver and passenger seats for a while now. Most also seem to "know" that this "isn't a good location". This is not true. The location from a midbass perspective is fine. Good, even. But the enclosure itself is absolutely horrid. BMW has an extremely tiny enclosure that vents into the rocker panel via a very small opening. This combo causes all sorts of issues such as early and steep low-end roll-off, resonance, unpredictable frequency response, etc. How we know this, well, we have a good deal of experience with doing sound systems in BMW's, and we even tried it first in this car before we did anything major.

The results were not up to par, and the phone call was made to get approval for the next step. Now many of you are going to think how we went about this is insane, but I promise you, how this was executed and its end results were great. Let's be real for a second.. BMW is not some low-tier manufacturer. There is a certain level of quality that goes into their vehicles. Unlike a Honda Civic for example (I only know this since I used to own one), this car has a full, plastic underbody cover. There is no real way for dirt or water to get to the actual metal floor pan, especially the specific area we are focusing on here. So what we did, we opened up the floor below the speaker and let it be in a true infinite baffle setup. Not only does this specific driver call for infinite baffle, but now we no longer have to deal with the resonance of the enclosure and the rocker panel regardless of what driver was used. How we went about this was actually pretty simple. We removed the plastic underbody cover, mapped out the area that the speaker enclosure covers, made sure nothing was in the way and nothing would be affected, and... started cutting. I know, blasphemous. But here's the thing. This is a single layer of non-structural steel. Nothing about this part of the car is needed aside from separating you from the outside, which we'd handle anyway. Once the area was cut away, it was sanded smooth, cleaned, primed, and then painted to prevent any corrosion. From there, we secured a primed/painted steel fine-mesh grill to prevent anything from getting to the speaker. We didn't bother using hydrophobic mesh as there is no way for water to get to this location with the underbody paneling fully assembled. Any other cars door would see much more moisture and dirt than this setup. In the end, the difference in sound was drastic, in the best ways possible.

Anyways, the rest of the build is fairly interesting. I may take the same approach but use drill holes instead. We'll see. Leave him some comments too...Cheers!

[I800C0LLECT]

We're losing about 12.5 decibels at 70Hz!!! Physics is a big deal. You can't fix that with different speakers or even multiplying amp power by 10x. The other perspective is that what your underseat subwoofer could do for 100 watts...it can now do at 10 watts.

For those that don't want to look through...you just cut out space underneath the the mid-bass. The response graph that shows the difference is an attachment. It's fairly significant...green is before and blue is after. Link to video below

[Panscan340]

No I’m not going to cut a hole in the bottom of my car. End of day it’s a car and that’s a bit wild. What happens when you drive through a puddle ? You have water splashing up against the magnet ? Pass.

[Gladius Nova]

Cutting a hole through the floor seems a bit extreme.

[I800C0LLECT]

Originally Posted by Panscan340

No I’m not going to cut a hole in the bottom of my car. End of day it’s a car and that’s a bit wild. What happens when you drive through a puddle ? You have water splashing up against the magnet ? Pass.

There’s another panel underneath the car that’s protecting it already. It covers the length of the underbody.

If this cutout was open to the road and weather you would see them create a protective barrier that looks like a vent covering it. Then they would add water proofing screens over the vent to protect against debris and puddles.

Originally Posted by Gladius Nova

Cutting a hole through the floor seems a bit extreme.

No more extreme than voiding warranties for performance. That area isn’t structural and it won’t change NVH characteristics. It can hurt resale for sure though as it just scares people off. You can just weld or epoxy the piece back in when you’re done. No harm no foul

In the video below is an approach that uses a manifold to hold two 18” subs. The way those two speakers are mounted also cancels out each others mechanical energy so you don’t hear any rattles or feel any vibrations moving through the car

https://youtu.be/lZGZWiYLVu0?si=42ec35cTpWq55RP2

[I800C0LLECT]

Here’s the panel that covers the under side of the vehicle and covers the hole

[I800C0LLECT]

Got an update…no cutting but added an amplifier and subwoofer.

Under seat subs are run by JL audio vx1000/5 that is bridged down to two channels. An AudioFrog GB10D4 is run by the sub channel.

I used the technic pnp harness and the amp’s onboard dsp to help correct the mid bass. I didn’t measure anything so I have a ways to go but filling in the bottom end made it easy to take the stress off the under seat subs. Now they’re set to 50Hz through 200Hz at 24 decibel slopes.

Big step forward in sound quality. However, it’s very easy to ruin the level matching been the speakers in the system this way.

Also, not real happy with the amplifier location as I prefer stealth or OEM look. But it made it easier to hook up to the laptop for tuning. Plus I can easily troubleshoot if I ever need to

[I800C0LLECT]

It is all tuned up… Huge difference!! Nobody would know that this was the standard HK speakers.

Adding the subwoofers allowed me to put a 80Hz filter on the under seat mids. It sounds great now with the sub handling 80Hz and down. The vx1000/5i amplifier has an excellent DSP built in. I haven’t measured, but adding at 150Hz helped a lot. Dialing in the mid bass and sub bass has really helped the upper range. The staging is much better now.

Powering the mids with the amp let me correct the few uses coming from factory. It really was an easy approach. Part of me wants to get the match up 10 but I’ll reserve that for the next time I get the itch to upgrade

[I800C0LLECT]

Always loved links helping me expose my own bias

blind test vs sighted test

[I800C0LLECT]

From infinite baffles install group on Facebook

Thank you Peter Steinbacher

[quote]
There you go for all the naysayers! Same floor location, same application in true-IB like the one you slagged off in the last 2 days. Solid mounting, zero flex or rattle. It’s been like this for the 2nd year, speaker is happy and dry. Layer of rainguard foam and BMW under tray keeps all moisture and water away and in UK it gets plenty enough.
Path length difference between this and most of your favourite door locations is actually 0.3ms less, easier to focus centre and they integrate to the mids seamlessly, especially as the only sound that you hear comes out of the speakers only and not out of rattling and flexing panels.
Ohh if you still doubt it’s pointless, then i have no idea how we could win European EMMA Finals in SQ E-Unlimited class with a car with 8”s in front of the seats in true-IB on the floor out of 15 cars that qualified for finals, which all finished in top 2 nationally in Europe. This install in post was also documented, all the test results, RTA evaluation and whatnot on all the Pssound social channels in the last years, 1000s of people have seen it and learnt from, so feel free to dig if this installation method is new for you (it’s been done plenty of times in the last 40 years too).

Just because you have never heard or experienced a solution, just because your creativity or freedom are limited, just because you’re a miserable keyboard warrior, it doesn’t mean that you should feel entitled to discourage others, who you don’t even know. Rather ask a question like “what are your expectations?” “How are you planning to solve x y z challenges?” “Have you thought about this/that?”.
Be helpful, feel free to help and give recommendations, rather give, than take. This is how we all move forward towards SQ happiness!🔊🔊
Have a successful and impressive IB year in 2024! 🎉
[\quote]

📸 Look at this post on Facebook https://www.facebook.com/share/CJpXW...ibextid=K35XfP

[I800C0LLECT]

Looks like I'm eating crow...I found the owner of that install in the G80. Here's what he said

I cut the floor on the floor of my G80 M3 to fit a utopia 8wm, and yes you definitely get more midbass though you also get a ton of road noise when the woofers are not being energized i.e. not playing any music. When you are playing music with bass the driver is energized and you can't tell the additional road noise but if music is off or listening to a podcast then you hear a ton of tire and road noise not worth it I'm my humble opinion, and I still think the midbass is lacking compared to properly sealed mids in the doors.

My only other thought is that if the 8" mid-bass can't breathe then you're left with two options.

1) Throw raw power at it...which I'm doing and I have hit the limits of them.
2) Use a 6.5" speaker...I have also done with extremely good results. That's probably the best answer. My last underseat install was with AudioFrog GB60 speakers.

We'll see what happens. I'm presently happy enough with the mid-bass. I have a RTA kit headed my way too so I can get some real measurements.

[CaleCro]

Originally Posted by I800C0LLECT

Looks like I'm eating crow...I found the owner of that install in the G80. Here's what he said



My only other thought is that if the 8" mid-bass can't breathe then you're left with two options.

1) Throw raw power at it...which I'm doing and I have hit the limits of them.
2) Use a 6.5" speaker...I have also done with extremely good results. That's probably the best answer. My last under seat install was with AudioFrog GB60 speakers.

We'll see what happens. I'm presently happy enough with the mid-bass. I have a RTA kit headed my way too so I can get some real measurements.

Im also now in beginning of SQ install to G20, and im researching what is the best option for midbass. As you writen here can you share any more info, pictures of Audiofrog installed?
Im also planning to go with 6.5'' and already prepared 3d model for adapter to fit...

[I800C0LLECT]

Adapters are easy to make but the real problem is air space. There’s always an issue of trade offs in car audio…just as noted above with the IB install.

As long as you’re installing a subwoofer then a 6.5” speaker should have plenty of excursion to handle 80Hz and above. Peerless has excellent speakers for this. But if you want an “exceptional” build quality that is better than most 8” speakers then an AudioFrog GB60 can’t be beat. An anarchy 6.5” is next along with Stereo Integrity MKV(I think?).

What’s great about a 6.5” is that it’ll be easier to install and you don’t have to worry about suffocating them.

If you don’t install a subwoofer then you need a slim 8” that is a jack of all trades. Almost every drop in speaker is about the same as or usually worse the OEM HK speaker. I highly advise you to install a subwoofer

[CaleCro]

Originally Posted by I800C0LLECT

Adapters are easy to make but the real problem is air space. There’s always an issue of trade offs in car audio…just as noted above with the IB install.

As long as you’re installing a subwoofer then a 6.5” speaker should have plenty of excursion to handle 80Hz and above. Peerless has excellent speakers for this. But if you want an “exceptional” build quality that is better than most 8” speakers then an AudioFrog GB60 can’t be beat. An anarchy 6.5” is next along with Stereo Integrity MKV(I think?).

What’s great about a 6.5” is that it’ll be easier to install and you don’t have to worry about suffocating them.

If you don’t install a subwoofer then you need a slim 8” that is a jack of all trades. Almost every drop in speaker is about the same as or usually worse the OEM HK speaker. I highly advise you to install a subwoofer

Well im going with STEG Masterstroke MSS6 for underseat, wanted to go IB, but as i can see road noise will be a problem, and 6.5'' can be a good solution without cutting the car.

In my case i will use for rear sub Morel Ultimo Ti124 and for front sub SB acoustics 10''... so will se how it will all blend in.


Another question - why you choose Right side for Audiofrog rear sub? any special reason or...

[I800C0LLECT]

That side is especially great for the driver. There’s cancellation issues when you have the subwoofer on one side only. The best spot is the middle of the car or rear center of the trunk.

That position is best for driver only

Edit: Assuming those are correct T/s...The speakers should be good for underseat use. That morel ultimo has amazing reviews too. It seems to blend so well that people aren't sure if it's the mid-bass they're hearing or the sub. Granted, it's punchy and sounds like a sub..it just blends that well. You should be very pleased! I got my microphone in the mail too so I can take some measurements now.

For tuning...check out the bottom of the page with all the PDFs

https://testgear.audiofrog.com/

and this is why for subwoofer...

https://www.diymobileaudio.com/threa...idbass.427251/

[CaleCro]

Thanks for info, but here on this video is visible dip in 60Hz....and there is slight difference up to 50hz for rear sub. So front sub is req. for sure here.

Do you have any photos of your 6.5 under seat how is mounted.

[I800C0LLECT]

The last vehicle I mounted 6.5” under the seat was in my 2013 Jetta hybrid. It was excellent…first time I ever received compliments without prompting. I had a lot of people try to copy it.

MS-8 ran it all. I had the same subwoofer back then but it was in the the spare trunk area.

I would throw caution to chasing down singular issues such as a specific frequency dip… as you likely won’t hear them. Just remember, one fix might break something else.


EDIT: You nailed one of the easier tricks to resolving response issues...one sub up front and another in the rear. There isn't much to rival that.

[I800C0LLECT]

Today I added filters to the tweeters in the doors. BIG improvement. It's a third order crossover around 4KHz

Quick and easy to install. I soldered the connectors I bought off Amazon so they're plug and play.