The BMW speakers at 300 can be OK. (more) (archive)

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300 Hz sounds high, but the "bass blockers" are only 6dB per octave, so it's only 6dB down at 150Hz. With the BMW, this happens to work OK because of two fortunate coincidences. First, the actual loudspeaker impedance is higher than the stated nominal 4-Ohms, effectively moving the crossover down from what is stated. It's really closer to 200Hz with the BMW speaker impedance. Second, the BMW head unit has a bass boost centered at approximately 100Hz, again effectively moving the crossover down. My guess is that the "300Hz" bass blockers are actually resulting in an acoustic crossover close to 100 or 125Hz.

Best regards,
Bob Hazelwood
Product Manager, Cambridge Soundworks
(formerly with a/d/s/)
'93 525i. Sharked, BL/ss'd, H&R + Bilsteins
BMW CCA (Boston)

: Wow, those 10's are handling all of your sub bass, and a lot of your midrange. The lowest I'd ever cut a mid to bass is 150hz. So the amp you got has a built in line driver I assume. Very nice. Did you build your own enclosure? I'm thinking about doing one with oak. (Last two cars I've done had oak/particle board and were solid as a rock) Would you mind sending me the wiring scheme you used? Thanks a lot!
: -Dan

: : I finally took Bob Hazelwood's advice and added a subwoofer to my standard E39 stereo. The results are fantastic. It sounds like a whole new system - I would recommend doing this first (the Stage 1 upgrade on the A/D/S website) before you go out and spend the big bucks on all new speakers and having to figure out how to get them into the doors etc....

: : It was all pretty simple after figuring out what wires needed to be spliced into from the amp ( I mapped out all the wire colors if anyone needs them). I purchased a 10" Kicker Solobaric woofer with the enclosure and an A/D/S P2110 amp. I put bassblockers on the 4 factory 5 1/4 woofers to cut out the lower signals under 300. Then I spliced into the two rear outputs going into the factory amp and sent that signal to the new amp.

: : Anyone who is worried about the sealed trunk - which I have - need not worry - I only have the amp set at about 1/4 capacity and the seats in the cabin shake from the bass already! No need to cut out the ski-bag thingie. If you turn the amp higher, you end up drowning out the tweeter and mids - guess I need a new amp for those too. The amp and box fit snuggly into the back corner of the trunk leaving plenty of space back there.

: : For those unhappy with their standard stereo in the E39, this upgrade will make you alot happier with a nominal amount invested. Also, thank you Bob Hazelwood for explaining how to do the upgrade...I saved some $$ by doing it myself.

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