[AGT SMTH]

Hey all,
I'm halfway done with my stereo but am now facing a serious dilemma... the car is a 2009 328i E90 sedan with no Logic 7, so it's nice and easy to upgrade (yeah). I've only had the car for a month or so and in reading online it seemed the trunk is very well insulated and I would need some significant sub power to get any sound inside the cabin. My solution a month back when I ordered everything was just to use brute force: beefy sub with gobs of power to drive it.

Unfortunately, it's far too insulated and now that it's installed I'm getting 80% trunk rattle and 20% cabin bass. The setup so far is:

MB Quart QSD 210 4" components in the doors and rear deck
Alpine PDX-4.150 4-channel amp powering the MB Quart's

Alpine SWR-1222D 12" Type R DVC 2 ohm sub in a sealed custom fiberglass box (left side of trunk)
Alpine PDX-1.600 mono amp powering the sub

Kenwood KGC-4042A eq mounted under steering wheel
3 farad cap, factory head unit
Factory amp powering the factory 8" under-seat subs

Picture so far with the sub box out of the car: (MB Quart crossovers are upside-down in the top-left and top-right corners of the picture)



So the problem: I can't stand the trunk rattle the sub is producing. It's an incredible sub, hits harder than hell and powered by that amp with the trunk open you think the world is coming to an end. But driving my shiny black BMW with that kind of rattle makes me look like some punk teenager (I'm 31, married with kid #1 due in March), it's embarassing. You can actually see the trunk's metal outside body panel on the side flexing with every bass hit.

So if I scrap the custom box and 12" sub altogether, could I use the PDX-1.600 to power a pair of Earthquake SWS-8's or would that just completely kill them? They appear to be 150W RMS each, my amp's certification sheet said it was producing 630W RMS. Or should I scrap the amp and downgrade to a "safer" Alpine PDX-2.150 which would put out 300W when bridged into 4 ohms?

I hate pissing away cash like this but man, that was a mistake. The ultimate sub in any car other than the ultimate driving machine.

Ironically, with the 12" sub out of the car and the factory under-seat subs put to +5 on bass, the setup sounds "excellent". The MB Quart's are phenomenal, no complaints there, and the factory subs hit hard--just not quite hard enough. Plus now I have a $500 amp just sitting there not plugged into anything. Damn.

Thanks for any input...

[AGT SMTH]

Oh yeah, additional question: anyone know if the factory sub wiring is good enough for the SWS-8's or should I run completely new higher-gauge wires?

[kaigoss69]

Originally Posted by AGT SMTH

Hey all,
I'm halfway done with my stereo but am now facing a serious dilemma... the car is a 2009 328i E90 sedan with no Logic 7, so it's nice and easy to upgrade (yeah). I've only had the car for a month or so and in reading online it seemed the trunk is very well insulated and I would need some significant sub power to get any sound inside the cabin. My solution a month back when I ordered everything was just to use brute force: beefy sub with gobs of power to drive it.

Unfortunately, it's far too insulated and now that it's installed I'm getting 80% trunk rattle and 20% cabin bass. The setup so far is:

MB Quart QSD 210 4" components in the doors and rear deck
Alpine PDX-4.150 4-channel amp powering the MB Quart's

Alpine SWR-1222D 12" Type R DVC 2 ohm sub in a sealed custom fiberglass box (left side of trunk)
Alpine PDX-1.600 mono amp powering the sub

Kenwood KGC-4042A eq mounted under steering wheel
3 farad cap, factory head unit
Factory amp powering the factory 8" under-seat subs

Picture so far with the sub box out of the car: (MB Quart crossovers are upside-down in the top-left and top-right corners of the picture)

So the problem: I can't stand the trunk rattle the sub is producing. It's an incredible sub, hits harder than hell and powered by that amp with the trunk open you think the world is coming to an end. But driving my shiny black BMW with that kind of rattle makes me look like some punk teenager (I'm 31, married with kid #1 due in March), it's embarassing. You can actually see the trunk's metal outside body panel on the side flexing with every bass hit.

So if I scrap the custom box and 12" sub altogether, could I use the PDX-1.600 to power a pair of Earthquake SWS-8's or would that just completely kill them? They appear to be 150W RMS each, my amp's certification sheet said it was producing 630W RMS. Or should I scrap the amp and downgrade to a "safer" Alpine PDX-2.150 which would put out 300W when bridged into 4 ohms?

I hate pissing away cash like this but man, that was a mistake. The ultimate sub in any car other than the ultimate driving machine.

Ironically, with the 12" sub out of the car and the factory under-seat subs put to +5 on bass, the setup sounds "excellent". The MB Quart's are phenomenal, no complaints there, and the factory subs hit hard--just not quite hard enough. Plus now I have a $500 amp just sitting there not plugged into anything. Damn.

Thanks for any input...

Yes, the PDX amp has the potential to blow those subs, but so does a $50 Walmart amp. As long as you set the gains properly, and play music responsibly, you will be fine. With the subs being inside the cabin, you will actually hear when they start to get too much power and distort or bottom out, so you can control the volume and prevent the damage better than for a trunk sub, where it is harder to hear the distortion. Also, the extra power (overhead) will give the amp better control over the cone movement which will give you cleaner bass at high volume levels and prevent amplifier clipping.

From personal experience, another thing you can do that will make those SWS sound better/cleaner and protect them from damage is to engage a high-pass crossover (if your amp allows it), attenuating frequencies below say 40 - 50 Hz, as the relatively small SWS and their enclosures do not really allow for any earthshaking bass notes anyway.

The only drawback is that you will be playing the subs in mono, and you will theoretically lose some imaging in the lower mid-bass region.

Oh, and the factory wiring is fine for 150W per channel.

[AGT SMTH]

Originally Posted by kaigoss69

As long as you set the gains properly, and play music responsibly, you will be fine.

Ack, the "r" word that wifey likes to use! That ain't gonna happen...

Originally Posted by kaigoss69

The only drawback is that you will be playing the subs in mono, and you will theoretically lose some imaging in the lower mid-bass region.

So from the factory they're two separate channels? (Didn't think to look.) Dang, that settles it... definitely need a different amp. Do you have any information on the factory subs, frequency response from the factory amp, etc? I'm having a very difficult time finding any info on OEM anything.

This may take some finesse. I only have one channel coming out of the EQ and that's "sub". So maybe the sub amp should just bypass the EQ altogether? Kind of defeats the purpose of having that fancy gain switch, but once it's set I should never move it. Argh, drawing board again.

Thanks,

[cbauer1227]

DYI the 8" SWS mod with MTX 300Xd amp this weekend. Have been doing a ton of online research. Check these threads. i found them helpful.

Frequency specs
http://www.diymobileaudio.com/forum/...-330i-e90.html

SWS mod tutorial
http://www.e90post.com/forums/showthread.php?t=134066

Wiring Harness diagram
http://www.e90post.com/forums/showth...wiring+diagram

I may post my experiences on this board too.

[AGT SMTH]

Hey, thanks, that wiring diagram was great! This afternoon I finally ordered a pair of the Earthquake SWS-8X's (4 ohm) from sonicelectronix.com and an Alpine PDX-2.150 from Crutchfield to run them. I've had many heart-to-heart talks with myself about the whole setup and decided to keep the 12... so now I need to figure out how to fit three Alpine amps back there. Not a bad problem to have.

Install probably won't be for at least 2 weeks. I'm far too lazy to compile a DIY but I'll take a ton of photos of the finished setup and post 'em once I'm done. 7 channels and, what, 1500 watts RMS total? boom

P.S. I ordered from www.sonicelectronix.com at 3:45 p.m. and got the UPS "your shipment tracking number is blah blah" e-mail at 6:30 p.m. And I'd selected free ground shipping, no "priority processing" or anything. Dayum!

P.S. 2 - I just checked my e-mail and lo and behold, there was a note from Crutchfield with my UPS tracking number--I'd ordered from them today at 4:30 p.m. Never in my life have I had an online order ship the same day, now twice in one day? This could be a sign...

[Atsnow]

Originally Posted by AGT SMTH

Hey, thanks, that wiring diagram was great! This afternoon I finally ordered a pair of the Earthquake SWS-8X's (4 ohm) from sonicelectronix.com and an Alpine PDX-2.150 from Crutchfield to run them. I've had many heart-to-heart talks with myself about the whole setup and decided to keep the 12... so now I need to figure out how to fit three Alpine amps back there. Not a bad problem to have.

..

Hey,
You will find that the SWS-8s with the Alpine in combination with your MBs will make for a well balanced system up front with a good butt massage,

the only thing you might find lacking in low end grunt

while it is true that BMW trunk are well insulated there are ways around that ( I should know I'm on my 4th BMW) , one thing I have noticed is that you hear bass much better if you use the trunk as a bass chamber ( not sure if that make sense)

what I mean is a 12" woofer in a proper box firing from the back of the trunk (near the bumper) (something similar to this http://www.e90post.com/forums/showthread.php?t=290391) will sound much louder in cabin then one like what you have , also if you have a ski pass leave it open

Personally I now have a 10" mass market sub powered by a about 300W Rms and I hear and feel it very well