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Been hella sick the last week or so, but finally got bored of sitting in the house so came in on a sunday to knock out a log. :)

Followers of our build logs over the years probably have seen us cram quite a bit of gear in some pretty limited spaces over the years...a lot of that has to do with our values of trying to make things look as OEM as possible and take away as little usable space as possible. This 2012 BMW 135i convertible, owned by our own member Tom aka. Tjswarbrick, is quite a good example of that.

We have known Tom a long time, and followed his progress in his previous mercedes C class, and interestingly enough, this project didnt quite start off as a space saving venture.

Like many of our members, Tom has collected a pretty extensive series of high end gear to be used in his next project...what he didnt know was the type of car that he was gonna purchase...as luck would have it, he ended up with a vehicle with VERY limited sacrificial space and very unique and limiting oem locations...and after sometime mocking up his existing gear, including arc SE amps, 12" subs, etc, and talking about just how much space he can sacrifice, it was decided that we would revamp most of the product list to better suit his desires for this vehicle.

the goals:

1. achieve a nice level of sound quality using oem locations

2. obtain a high level of bass performance despite the convertible configuration

3. sacrifice as little space as possible in an already limited trunk

Jesse did most of the work on this build, while Joey built the sub enclosure...i just did the tuning and the write up :)

lets get started.

first the car...this is our first 1 series of any kind, just happens to be a convertible :)







one of the biggest obstacles to making a convertible with a sealed off trunk sound good is the subbass performance. Subs located in the trunk separated by solid panels and the convertible mechanism, simply dont have a very good chance of getting into the cabin...thus, apart from unique vehicles such as the s2000, almost every other convertible we have done a subwoofer in the interior. The difficult part for this car is that it is a pretty small interior to begin with, so here is the view of that interior:





as you can see, it remains pretty much stock looking. :) only very keen eyed owners of the 135 can perhaps notice that the passenger side floor mat is raised a little bit higher than normal...honestly, not being so familar with the vechile, i couldnt really see it even while i was taking the pics:


well, beneath the carpet lies a sealed enclosure housing an illusion audio Carbon C10 10" subwoofer. :) the middle of the enclosure is finished in graphite vinyl, while the two sides were wrapped in the actual floor carpet that was trimmed and reattached. this means with the floor mat in place hiding the vinyl portion, it is very difficult to pick out the enclosure. The sub itself is protected by a press fit mesh grille that still allows a view of the unique C10 subwoofer:















here are some build pics of the sub enclosure by Joey. first, the area that will house the subwoofer enclosure was marked off and the carpet trimmed. one of the nice things about this car is that the passenger foot well is spaced up by a super thick piece of foam. with this section cut out of the car, it gave us quite a bit of room to build a decent sized enclosure and not protrude out too far from the oem floor level. :)







then the whole area was tapped off, and several layers of glass laid down to form the back side of the enclosure:







then joey got to work on the front baffle for the enclosure. with the unique front magnet design of the sub, the sub itself has to be inset quite a bit, so a stack of rings was built into the baffle to achieve that purpose. also, the press fit grille itself, which eventually becomes even with the front baffle, had to be several stacks high as well:













the side of the stack of rings was then ground down so it would fit within the confines of the floor mold, and then another top piece was attached, and the rings sealed off with druaglass:







this piece was then mated to the back mold, forming the complete enclosure of a little under .5 cubic foot, it is a bit small for the c10, but from past experiences such as our Mini and E30M3 build, we know the C10 performs beautifully in tiny boxes upfront. :)





the bonding area between the mold and the front baffle was then smoothed out, and basically, looking at this picture, the part that is in filler is how little the enclosure is raised from the oem floor...about 3-4 inches at the top and very little on the bottom:



the box was then fitted back into the car, and the edges backfilled to form a perfect fit with the car's foot well space:



when that cured and was sanded, the enclosure was once again test fitted in the car:





then came time to build the top trim layer, which started off as a single piece of 1/8" mdf. it was trimmed so the mdf itself will be in vinyl, while the sides in the salvaged factory carpet, and the difference in thickness between the two materials made for a flat top surface when done. :









so here is a pic to show just how far recessed the sub is:



and here is joey rabeting the inside edge of the grille to allow the mesh to be fitted from underneath the top most layer of the grille:



 

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then, the mesh was temporarily secured, and the whole box test fitted together one last time:





then the vinyl and carpet went on, and once again, the enclosure was test fitted to ensure proper fitment:



the grille was also wrapped in vinyl and the mesh attached from the backside:





and the box was wired up, the center portion painted black, and stuffed with blackhole stuff, and is now ready to go back into the car:















a final look at the foot well before the subbox went in:



moving onto the rest of the front stage.

for the oem door midrange location, Tom supplied us with an older set of ADS 4" midranges and some aluminum mounting baffles. jesse wired the speaker up, and secured them to the oem locations and sound proofed around the mounting to help with resonance:













for tweeter duty, we supplied the car with a set of Morel Elate MT350 tweeters, as they fit in bmw stock locations perfectly and has proven to produce great results:







the oem underseat woofers were replaced with a set of gladen oem fitment drivers, jesse fully sound proofed the enclosures inside and out before bolting in the gladen drivers:







next came the wiring, and being a bmw, it was almost impossible to take good pics of the wiring once its tucked under the carpet in the door sill channel, so here ist he bundle still outside of hte car:



so thats it for the interior, moving onto the trunk.

so this is a pretty darn small trunk to begin with, and with the convertible top stowage taking up quite a bit of the depth, it was a challenge trying to conceal all the amps and dsp...keeping in mind that the car's stock locations dictated two amplifiers for this job.

But after some thinking, jesse came up with quite a brilliant mounting and trim for the amps. :)

so here is the view from back of the car...and if you dont look really hard, it is easy to miss what Jesse added:



basically, a trim panel with a center vinyl trim and press fit grille resides on the driver side the trunk, it barely takes up any real trunk space and through the grille, you can see the profiles of an arc audio xdiv2 amplifier. even though this looks very simple, it took quite a bit of trial and error and careful fitment to achieve, and i am really proud of Jesse for this one..note especially the profiled curves on the front surface so as to make it blend better with the lines of the oem carpet:















lift up the oem floor board, and you see a mobridge DA3 at the front of the trunk well, that provides signal source and all the processing for the system, and if you look closely at the back, you will see a stinger fuse block next to the battery:



 

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onto the build pics of the trunk.

first up is the little holder for the fuse block...which jesse fabricatged to snap into a cavity in the oem trunk well divider:





To house the two amplifiers in a verticle stacked confifguration, jesse came up with a two part platform. here is the foundational portion that bolts to the car itself, sitting inside the cavity on the driver side trunk corner, it is foamed to prevent rattles and is very sturdy as to provide a solid mounting bass for the actual amp rack:







and here is the actual rack itself that houses the two amps, a 1200.6 powers the mid, tweeter and subwoofer with 150, 150 and 600 watts, while a 600.4 is bridged on the midbass sending them 300 watts a piece. this rack is also very strudy to prevent any flex when the car is in motion. this rack bolts to the foundation platform to secure it solidly in the car:













so here is the amp rack bolted to the car and wired up:





and here front trim panel...which basically started out as a piece mdf cut to fit the area, topped with anotether strim of mdf, the corner profiled with cardbard and fiberglass, and then a center trim area cut out and backfilled with filler to present a presfit cavity. the rest of the area was then profiled with more fiberglass and filler; while the center preset grille is fabricated out of mdf and note the pressed grille that actually raises up in the middle to become even with the top surface of the grille. it looks very small and simple but presents quite a bit of work to get right:









here is the piece test fitted one final time before upholstery:



and finally, here is the entire piece after upholstery with carpet and vinyl, with the carpet being dyed darker to better match the oem carpet color, and the grille piece press fit in place:











so thats it! if there ever was a build that has a lot more than meets the eye on the surface, this is it...i am super happy with how it turned out from a cosmetic fit and finish stand point.

as for how it sounds, i think Tom is knowledgeable enough to present his own thoughts..and with some more tuning at more capable hands, i am sure it will shine even more.

for me, the car sounded very good, very similar to other late model bmws we have done that has very similar locations and equipment. the staging and imagine are all quite decent, with very smooth tonality that can reach very high volumes.

the subbass is truly something else tho. with the open air nature of the car, extreme bottom end below 30hz suffers a bit due to lack of cabin reinforcement, but above that, the impact, transient response, and blending of this car is something else. we do not get to do a lot of front subs, so when i listen to the various tracks on my own test cd, especially the ones featuring snappy snare trunks and bass notes, it is quite an experience in this car...everyone likes to say their drums slap them in the chest, this one seriously does and is very cool to listen to.

well, thats it for now, time to get some more rest to recover for the busy work week ahead.

until next time,

Cheers :)

Bing
 

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Nice work on everything ! that amp cover is quite a project with detailed work and looks great! :thumbsup:

Is that 2 gauge power wire on the amp? It looks thick. What power size wire was the main line ? Sorry I could not see the main one.

Maybe it's just the pictures since that MDF also looks like over 1" thick :) making me guess is 4 G wire

I may get a chance to listen and see it all eventually ;)
 

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very off topic, but whoever tagged that box before it was wrapped, i like your style
 

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i think its 4 guage all around on this, being so close to the battery. but jesse can confirm.

i keep telling jesse that he should be some kind of illustrator or designer with that hand writing thing of his...:)
killah shark sjc.
 

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that sub box is niiiiice. I remember Tom showing me his trunk before the install and it is so small, couldnt imagine how all the gear could fit, this is def a very nice solution. Cant wait to get a demo. :)
 

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10 lbs of gear in a 5 lb bag is right!
Jesse, JOey, and Bing - I am SO pleased - nee, awestruck, by your gear recommendations and installation. It looks so clean and hides so well.
The day I picked up the car I loaded it with camping gear and headed to the hills (okay, over the hill) with my daughter. Everyone else had minivans, and I was the one carrying the coolers! Everything fit, and the drive was an utter joy.

Bing is right - the impact and tunefulness are astounding. I'm still playing with the tune, and getting a handle on the DA3, but mostly I'm trying to minorly improve the timing without honking up the initial sound.

Jesse - wow - you weren't kidding about those amps being a tight fit in there. Thanks for making the perfect rack for 'em!

And JOey - that sub enclosure just hit it out of the park for me. The repurposed carpet was a stroke of genius. It makes it look like it was built that way in Germany.

Thanks guys.
Loving it more every day.

- Tom
 

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Nice work on everything ! that amp cover is quite a project with detailed work and looks great! :thumbsup:


I may get a chance to listen and see it all eventually ;)
that sub box is niiiiice. I remember Tom showing me his trunk before the install and it is so small, couldnt imagine how all the gear could fit, this is def a very nice solution. Cant wait to get a demo. :)
Demo coming soon...
 

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I can truly say that I am very impressed with how that front subwoofer is integrated. I have a friend who didn't want to give up any trunk space for an enclosure, and now I can show him this. :)
 

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Nice work SiS Team!

Congrats Tom, you must be so stoked!
 

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You guys continue to amaze me with your ability to take it up a notch. How is the sub enclosure attached to the floor?
 

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Thanks Tom! Glad you like it! It was fun to build (my part anyway... )


10 lbs of gear in a 5 lb bag is right!
Jesse, JOey, and Bing - I am SO pleased - nee, awestruck, by your gear recommendations and installation. It looks so clean and hides so well.
The day I picked up the car I loaded it with camping gear and headed to the hills (okay, over the hill) with my daughter. Everyone else had minivans, and I was the one carrying the coolers! Everything fit, and the drive was an utter joy.

Bing is right - the impact and tunefulness are astounding. I'm still playing with the tune, and getting a handle on the DA3, but mostly I'm trying to minorly improve the timing without honking up the initial sound.

Jesse - wow - you weren't kidding about those amps being a tight fit in there. Thanks for making the perfect rack for 'em!

And JOey - that sub enclosure just hit it out of the park for me. The repurposed carpet was a stroke of genius. It makes it look like it was built that way in Germany.

Thanks guys.
Loving it more every day.

- Tom
 
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