So when I first got my 08' 528 I was like most...didn't like the sound in the car. So I purchased the BSW speaker package to upgrade my speakers. When I took the for installlation they talked me into focal 100krs poly lass speakers. They put a JL Audion XD 7 amp in and amped the OEM subs under the seat. Now I want more. I am going to get the Audison bit one installed, but they are trying to talk me into getting a JL Audio stealth box for the trunk. I don't want metal and my license plate rattling. So two questions:

1. Anyone have the stealth box that can speak to it?

2. Will I be ok with just the Audison Bit One upgrade?

 

How many channel is your XD amp? The stealth boxes are just a prefab sub box that goes behind the rear wheel well, saves the shop from having to fabricate something for a sub. The bit-one's are nice but all manual tuning and no logic 7, is your factory system the logic 7? If you have logic 7 and want to keep the center speaker then I would consider a JBL ms8, the ms8 also has a pretty decent auto tune.

 

No...it's a non logic 7. The amp is 5 channels. I saw the box, but again worry a little about rattling and such.

 

the bmw is pretty solid and shouldn't have too much rattling, nothing that can't be cured. If your shop is going to be doing all your tuning and you aren't one to want to fiddle with it much then the bit-one is a solid unit. Many amateurs prefer the ms8 because of the auto tune, without a RTA the bit-one is tough to tune well. I debated this for a while and ended up with the ms8, but either way you will need some sort of processor. You may want to consider replacing the oem subs under the seats with some mid-bass speakers to fill the frequency gap between the 100krs and the sub that will be in the trunk. Use the front 2 channels of the amp to power the focals and the rear 2 channels to power some midbasses under the seats and the sub channel for the sub in the trunk.

 

So you don't think it will sound right without doing the sub?

 

I think it would sound best with a sub and then some midbasses under the seats.

I'm not sure that the oem subs under the seats are going to be able to give you much more. the other option is try and replace the oem underseat subs with some different subs that will fit there and powering those. How is your amp wired up right now? It sounds like you have a 5 channel amp but aren't using all the channels right now. Also are you just taking the high level signal from the factory headunit and feeding straight into the amp? Are the focals amped right now?

 

Right now the oem subs are powered by the amp. The vocals are also powered by the amp.

 

I think the best solution would be to figure out what options your shop has for midbass that will fit under the seats where the oem subs are, get a sub for the trunk and eq everything with the bitone. That would be what I would look to do with what you have, although you can always scale down from there as you see fit.

 

Thanks Cleung!!