It gets better. Vacation time is tinker time :-)
Dynamatted the under seat sub enclosures to death and blocked the ports. Much much better.
Removed the capacitors that are in series with the front speakers - caps are in the side storage in the trunk wrapped in foam btw.
At full head unit volume the bass now overpowers the Alpine 410s. ie audible distortion in bass from the poor little blighters.
Added the capacitors back but increased them to 300uF (bipolar cross over caps) to get a low frequency roll off about where the under seat subs are cutting in. Can now run at full head unit volume with no distortion and no reverb. Very crisp bass with good punch to the midriff. Heck of a difference to stock.
Summary to date:
- Replace the front door speakers with Alpine 410s (not the rear - leave as stock)
- Replace the under seat sub with earthquake SWS-8X (4 ohm)
- Dynamat the enclosures and seal the ports (with dynamat)
- Add focal solid 2 amp in the hidden area under the floor in the trunk to run the subs. Use the high level speaker lines from the stock subs as input to get auto power on/off. Set to low pass with rollofff at 150 Hz. Set to approx 25% gain.
- Replace the capacitors in series with the front door speakers with 300uF crossover caps - caps are located in the side access hatch in the trunk.
I have ordered an Alpine PXE650 for further trimming. Will be interesting. e.g. will need another 4 channel amp to run the front door speakers and the rear door speakers to be able to use the PXE to best effect.
X3 3.0d 2006 (MY07)
Last edited by x3oiler; 12-30-2011 at 12:47 AM.
Reason: typo - always typos no matter how much proof reading