Luke's Box with an M3 rear bench? NE1?

[StereoInstaller1]

I have shipped a couple of boxes down to "the bay area" (might even be one in Walnut Creek?) so see if you can find someone near you to compare to.

The big trick is getting 100% of the output form the sub into the car. That is where every single attempt at copying my work has failed.

I can tell you guys this: I am gonna try to find time to re-do mine before the picnic this year. If so, all y'all gonna be pissed!

[svn2002s]

I am going to build two boxes and compare the sound. The first one, something similar to Luke's box and the second one with the ports pointing up to the speaker holes on the rear shelf.
I won't be removing any foam from M3 rear bench. (I'll be running a dedicated sub amp with a 10 in. Jl Audio). I'll post my opinion on both setups.

[StereoInstaller1]

I hear ya there... When you say cut foam do you mean cutting about 3'' depth into the seat about the size of the ski pass cutout? I think I will be having to do this since I don't want to cut holes in my rear deck or can source a armrest rear seat by me...

I cut the foam out from the backside...bummer I don't have a pic!

I will tell you this: using one of my normal ported 10" boxes and an infinity 1030W (typically $50ish) on a pioneer GM3300T (maybe 150 RMS on a good day, about $75ish?) I got plenty of bottom end, like about 125ish DB at well below 30Hz...and it weighed about the same as the trunk tar I pulled out, and the depth at the top of the box is 4"...with superb quality of sound.

[Massive Lee]

Interesting thread that's giving me ideas. I have BMW's premium speakers and a nice Pioneer head with 4 x 45w amp and all sorts of sound shaping gizmos. Sound is good, but I feel I need more nbottom... I also have two pairs of Kef B138 "racetrack" woofers and could used one or two to add bass.

One spare set is 4 Ohms, the other is 8... Hmm.. ;-)

[mrbobian]

It is called "compromise" my man...I just like the ones I pick, best.

I do cut out 3" or so of foam on the heavy leather, cloth and M3 seats, only where the ski pass is. It makes a huge difference.

I hear ya there... When you say cut foam do you mean cutting about 3'' depth into the seat about the size of the ski pass cutout? I think I will be having to do this since I don't want to cut holes in my rear deck or can source a armrest rear seat by me...

[StereoInstaller1]

Does anyone with ports running into the cab but sub covered up by the seat have a problem with peaking around the tuning freq? It seems like a hell of a lot more sound would make it though right at tuning if the ports were in the cab and the sub really wasn't...

It is called "compromise" my man...I just like the ones I pick, best.

I do cut out 3" or so of foam on the heavy leather, cloth and M3 seats, only where the ski pass is. It makes a huge difference.

[mrbobian]

Does anyone with ports running into the cab but sub covered up by the seat have a problem with peaking around the tuning freq? It seems like a hell of a lot more sound would make it though right at tuning if the ports were in the cab and the sub really wasn't...

[ck_taft325is]

You don't need a ski-pass through seat. Behind the regular seat there's a punch out piece of sheet metal you remove. You can drill some holes in the center foam directly behind it and mount a box (sub facing in with ports up to the speaker deck) to get better sound quality.

[foglght]

So if I have an '89, I should have a ski pass?

Crap, don't have a fold down seat, so what should I do? The one I have is in really nice condition.

[Gruelius]

nah my parts 30 has the ski pass so ill just check that out lol, im tempted to try and headbutt it out when the insurers tell me how much my cars worth (my 5 month project e30 got written off 20 minutes after i registered it when someone crashed up the back of me, was driving it home from vicroads (registration place where they have to sight the car) and cause i got no insurance im up shit creek for arguing my cars assessed value)

[StereoInstaller1]

I can't claim to be any kind of structural engineer for anything beyond subwoofer boxes, and I can tell you I cut only what is needed to make the bass work...but the cars with the ski pass do have 2 vertical braces running on either side of the hole.

Grab a mates car and peek in there, with the false wall off, you will see what I mean.

Luke

[Gruelius]

ah i thought it was luck of the draw good to know that its a years thing.

Does the ski pass have any structural benefit?

** well i mean the wall thats there (not the flimsy knock out ski pass)

[StereoInstaller1]

not my car but same deal

Yup, if there isn't room in the trunk to fit a battery (318i, 325, pre-86) you have no ski pass.

I have done 2 like yours. Both got holes cut!

[ck_taft325is]

Scrooged.

[Gruelius]

not my car but same deal