[mdw]

There's an M2 in my near future , but the HK system needs to go. I would love to put something like these JL 10 TW3-D4 speakers under the seats. The work will be done by an outstanding shop, so I am certain they will do a great job. My concern is whether I should try to get away with under seat.

Anyone feel like sharing their under seat (or not) thoughts?

The shop I go to will try their best to get me to put the sub in the trunk, but if the M2 is anything like my 98 323is, then I want to avoid loosing the trunk space unless the gain is dramatic.

[Viffermike]

Originally Posted by mdw

There's an M2 in my near future , but the HK system needs to go. I would love to put something like these JL 10 TW3-D4 speakers under the seats. The work will be done by an outstanding shop, so I am certain they will do a great job. My concern is whether I should try to get away with under seat.

Anyone feel like sharing their under seat (or not) thoughts?

The shop I go to will try their best to get me to put the sub in the trunk, but if the M2 is anything like my 98 323is, then I want to avoid loosing the trunk space unless the gain is dramatic.

Read this thread, then this thread. Then, do some more research on this subforum.

First off: those JL Audio drivers will not fit under your seats. The space is for an 8-inch driver; those are 10-inchers.

Second: You need to define what 'bass' is to you. See the first thread I link to above. Bottom line (pun slightly intended) is that you really only need a sub if you listen to music with regular excursions below 60-80 Hz: Hip hop, dub, orchestral music, some heavy rock.

Third: The OEM drivers under your seats are not subs: they are mid-bass drivers that occasionally can reproduce sub-bass frequencies. "Sub" is often used improperly in car audio because it's a selling point to the uneducated (i.e., most buyers). You already know that the HK is not all that good a system. The 'subs', in fact, are the best part of that system stock.

Lastly: If you do decide to install a sub, you will absolutely have to power it with a separate amp, no matter where the location. The stock amp simply does not produce enough power to drive a sub properly.

That you're working with an aftermarket shop is a step in the right direction. Listen to what it has to say, but be skeptical of what it recommends -- because in the end, a shop is going to want to sell you as much gear as possible, whether you actually need it or not.

[yatesfloyd]

I have the stock hifi system but I am getting a 10 inch audiofrog sub in my trunk installed tomorrow (powered by a micro 450w amp) I will let you know how much of a difference I notice.

[mdw]

The question of whether to go trunk, as I've been lead to understand is best, or under seat still stands. I have no experience with good subwoofers in a car, so I'm a novice.

Viffermike, Those links look familiar, but they're primarily about amps, wiring, and speaker selection. Huge thanks regarding speaker size; I didn't know under seats were limited to 8". Sub bass for me is the stuff that makes things shake, rumble, and bump (electro, dub, some rock ... ~ 60 Hz). Understood regarding amps. I expect a couple (or more). My shop is really good about advising me; I just don't want to loose trunk space unless I have to.

Let me know how it goes yatesfloyd.

Viffermike's point about the JL 10's not fitting under the seat make me suspect the trunk is inevitable. Hope not.

[yatesfloyd]

Originally Posted by mdw

The question of whether to go trunk, as I've been lead to understand is best, or under seat still stands. I have no experience with good subwoofers in a car, so I'm a novice.

Viffermike, Those links look familiar, but they're primarily about amps, wiring, and speaker selection. Huge thanks regarding speaker size; I didn't know under seats were limited to 8". Sub bass for me is the stuff that makes things shake, rumble, and bump (electro, dub, some rock ... ~ 60 Hz). Understood regarding amps. I expect a couple (or more). My shop is really good about advising me; I just don't want to loose trunk space unless I have to.

Let me know how it goes yatesfloyd.

Viffermike's point about the JL 10's not fitting under the seat make me suspect the trunk is inevitable. Hope not.

System specs
- 10" audiofrog GS10 subwoofer (in a f22 fitted Musicar Northwest enclosure)
- Rockford 450w micro amp
- mounting plate for micro amp (to fit next to stock)
- T harness (plug and play)

So I had my trunk sub installed today and it was awesome. However, I was shuffling through SoundCloud's stream option and the sub was better with certain songs obviously. For instance I like rap and house music, which both played phenomenal in my car. Other various pop genres sounded good. I don't listen to rock but I didn't notice the sub having a huge impact on the genre as a whole (obviously a guitar won't come through with deep notes).

Things I've noted since I got installed:
- golf bag still fits in trunk at an angle
- there is some rattling (not too bad tho)
- I now have a badass sound system

Note: I am trying break it in gently with like 3/4 max volume

Overall: 9/10 with OEM look, fit, and hidden amp as well as the loud deep bass made this a very good fit for me. I wouldn't give it a 10 simply due to the minor rattling, but it's something I'll fix or just learn to live with.

In my opinion it comes down to what music you listen to. Rap, hip-hop, trap, edm, house, pop, etc. all sound amazing. You can ask me to play a song or two and I'll let you know what it sounds like.

[matt@bavsound]

mdw - the quick answer is why not both?! As Viffermike stated, the speakers under the seats are 8" shallow mount drivers with not a ton of excursion and a relatively small motor structure. Depending on your personal music and sound system preferences, upgrading to beefier drivers like our GhostSubs, ones from Gladden or Rockford Fosgate could make you completely happy without going through a ton of effort.

If you find that you want more low end than just the underseats provide, then you could simply set them for midbass/high subbass frequencies through the use of a crossover. Then, add a slim sub in the trunk as well in a small enclosure that occupies the least usable space possible, such as the spare tire well, under the rear deck, or in the side between the shock tower and taillight. Any good audio shop will be able to use mdf, baltic birch and fiberglass to fit a nice shallow sub in a tight spot to retain your trunk space. This true subwoofer would be set for low subbass frequencies that it is truly capable of handling, and would be crossed over to naturally roll into the underseat woofers, then the door midbasses.

The simplest and cheapest route I'm suggesting is just swapping out the drivers under the seat to see if you're happy enough at that, or going all in with a multi-channel amplifier, soundfield processor (such as the Audison BitTen) and adding a trunk mounted sub as well. The benefit with the latter would be that all frequencies will be sent to drivers that can truly reproduce them, and you won't get any of the "bass in the back, music up front" sound that plagues so many cheap and poorly thought out audio systems.

Hope this helps, and let us know if we can be of any help!

[Solarphil]

Originally Posted by matt@bavsound

in a small enclosure that occupies the least usable space possible, such as the spare tire well,

Hey, let me know when you find that spare tire well, i've been looking for mine for a while and can't figure out where they hid it.

Seriously though, your input is appreciated and I've had to cover the company line on a forum myself so I know what your job is like, but please, respectfully, no cut-n-paste answers on a model-specific forum.

[Viffermike]

Originally Posted by Solarphil

Hey, let me know when you find that spare tire well, i've been looking for mine for a while and can't figure out where they hid it.

Seriously though, your input is appreciated and I've had to cover the company line on a forum myself so I know what your job is like, but please, respectfully, no cut-n-paste answers on a model-specific forum.

Hear, hear! (pun totally intended).

Though: the Bavsound rep did include some good info. Example: the underseat space, which is very shallow and really isn't nearly enough to help move air like a sub should. That's another reason why sealed enclosures are favored for car subs: to function best, the driver assembly needs a baffle behind the cone that is ideally of a set measured volume that offsets the air moved by the front of the cone. To put it simply: when this space is too small, the excursion of the cone is limited and the sound pressure is choked off; when it is too much, impact and SPL is severely curtailed. Think of that baffle as a form of 'air suspension', and you'll understand it better.

OP: sounds like you've got a handle on what you'll need. I'm sorry to say the underseat space just isn't close to ideal for that need.

[mdw]

Thanks so much everyone. I really appreciate all the comments; much to consider. Wish I had the car today, so I can better visualize things, but I gotta wait till it's built. Grrr.

yatesfloyd Glad to hear (no pun intended) that you've gotten a 9/10 _and_ still manage to get your golf clubs in. Yay! Where in the trunk did you mount the sub? "You can ask me to play a song or two and I'll let you know what it sounds like." ... please, Intermixture- Liquid Fidelity is on soundcloud. There are killer drops sprinkled throughout; you'll know when you hear them.

M

[yatesfloyd]

Originally Posted by mdw

Thanks so much everyone. I really appreciate all the comments; much to consider. Wish I had the car today, so I can better visualize things, but I gotta wait till it's built. Grrr.

yatesfloyd Glad to hear (no pun intended) that you've gotten a 9/10 _and_ still manage to get your golf clubs in. Yay! Where in the trunk did you mount the sub? "You can ask me to play a song or two and I'll let you know what it sounds like." ... please, Intermixture- Liquid Fidelity is on soundcloud. There are killer drops sprinkled throughout; you'll know when you hear them.

M

You can see my trunk space/setup here with the golf clubs in the back too. The musicar enclosure fits in the little inlet on the side that wasn't really usable space anyway, so I didn't lose much trunk space.
[IMG][/IMG]

Intermixture's low notes (the ones my sub picked up) sounded good. 50% volume was good. 75% volume was great. 100% caused noticeable rattling but the bass was overwhelming it. You won't really notice the deep bass under 50% volume though.

[mdw]

Thanks again yatesfloyd. Glad to hear that intermixture came through ok.

"You won't really notice the deep bass under 50% volume though."

Same on my home stereo; I have to pump up the volume to get the thump. I attribute it to the mix.

" The musicar enclosure fits in the little inlet " (the IMG tags are empty BTW)

Great, I'll head over to the dealer and take a look.

[yatesfloyd]

Originally Posted by mdw

Thanks again yatesfloyd. Glad to hear that intermixture came through ok.

"You won't really notice the deep bass under 50% volume though."

Same on my home stereo; I have to pump up the volume to get the thump. I attribute it to the mix.

" The musicar enclosure fits in the little inlet " (the IMG tags are empty BTW)

Great, I'll head over to the dealer and take a look.

Sorry posting off the phone is weird. Here it is.

[BentZero]

Originally Posted by yatesfloyd

Sorry posting off the phone is weird. Here it is.

Do you have a pic and source for the mounting plate or did you just fabricate one?

[yatesfloyd]

Originally Posted by BentZero

Do you have a pic and source for the mounting plate or did you just fabricate one?

It's musicar northwest's mounting plate. It's under the trunk liner in the OEM spot. May be able to ask them for a picture.

[matt@bavsound]

Originally Posted by Solarphil

Hey, let me know when you find that spare tire well, i've been looking for mine for a while and can't figure out where they hid it.

Seriously though, your input is appreciated and I've had to cover the company line on a forum myself so I know what your job is like, but please, respectfully, no cut-n-paste answers on a model-specific forum.

I don't know if it's my writing style or what, but I get that copy and paste comment more than I'd like! That response was typed by these little fingers specifically in response to the thread. Definitely my bad on the spare tire well comment - I neglected to remember that the 2 doesn't have one...oops.

I really do feel (after a lifetime doing audio in all types of cars) that the best dedicated audio setups have as much midbass/high sub bass in the cabin, and then a dedicated sub in the trunk that's running somewhere around 60hz and below. We used to do 8" woofers in the doors of customers cars, in the floorboard, under the dash, under the seat, etc. (Not being model-specific there - I used to build systems in all makes and models) At the very least, some solid 6" midbasses sealed front to back with plenty of sound deadening wherever possible.

In these cars specifically, I'd highly recommend upgrading the underseat subs with any of the offerings out there (including ours), and if you still want more and are willing to add the complication of another enclosure and amp, putting at minimum a 10" in the trunk crossed over as mentioned above.

Bummer BMW didn't give the 2-series the spare tire well option, but in the quarter panel or under the rear deck are also great options.

Please do let me know if I can help. It's what I'm here for.

[matt@bavsound]

Originally Posted by yatesfloyd

Sorry posting off the phone is weird. Here it is.

Exactly what I'm talking about right there! That's a nice looking enclosure that doesn't kill the usability of the trunk...

[yatesfloyd]

Originally Posted by matt@bavsound

Exactly what I'm talking about right there! That's a nice looking enclosure that doesn't kill the usability of the trunk...

And don't forget the bumpin' bass

[mdw]

Yay! The M2 arrived, and the stock HK system was poor as expected. No problem. Benchmark Motoring, Bellevue WA, installed some upgrades, and it now sounds outstanding. Special thanks to Justin who arranged everything and Sonny who patiently worked with me on the equalization. Hardware notables include an Audison AP8.9 bit 520 W amplifier with dsp, JL Audio 10TW3 10" subwoofer, and a custom enclosure fabricated by Benchmark. The subwoofer fires toward the side panel and there is a 1" or so air gap around the enclosure back (shadows).

Equalization was a bit of a chore. With tone control flat on both iDrive and audison DSP, there was a huge hole in the bass just above the sub crosover. Bass lines about the crossover when from booming (subwoofer) to empty (8"ers under seats) and back again. Using a spectrum analyzer and ears, we were able to EQ the system so those bass lines seamlessly transitioned between speakers.

I am extremely pleased with the sound, and the trunk has room enough for my stuff.

[ryem3]

Seriously added a sub and amp and left the stock speakers alone? Interesting.
Interesting comments here noting that a lot of mid bass comes from the underseat subs. Seems like it would really be worthwhile to replace them, even if they are the best part of the hk system.

[mdw]

Originally Posted by ryem3

...
Interesting comments here noting that a lot of mid bass comes from the underseat subs. Seems like it would really be worthwhile to replace them, even if they are the best part of the hk system.

I kinda share your thoughts, but I went with the shop's recommendation, and we were able to get it EQed with the stock underseats. I've had a week with it now, and the sound isn't quite as good as my home system, but it's close. The dynamics are great, and the sound is well balanced at volumes up to ear pain levels (I haven't tested beyond). No clips, distortion, or hiss.

[ryem3]

And you left ALL of the other stock speakers in? The stock speakers really could use upgrade, although I have heard worse stock systems.