Alternator and stereo power question, 87 300D - PeachParts Mercedes-Benz Forum

BodhiBenz1987 · #1 08-16-2009, 04:57 PM

I installed a new HU in my 87 300D a year ago and then had 4 Focal speakers installed in the stock locations, powered by an Alpine PDX-5 amp (75X4 + 300X1), which also powers a 12-inch Polk sub which has I think 350W RMS. The system sounds incredible in terms of sound quality and really kicks out powerful, clean bass. The only thing I've noticed -- and this kind of goes counter to what I would have thought -- is that the system, notably the bass, seems to lose a little oomph at highway speeds. I do realize some of this may be perception, as there's more highway and engine noise to make the music seem quieter. But there seems to be a noticeable difference: I.e., if I turn the volume up to 3/4 power at 20 mph, it's pretty much too powerful to stand ... if I turn it up to 3/4 at 60 mph, I can feel the bass, but not anywhere near as well. Isn't this the opposite of what should happen? Doesn't the alternator put out more at 3,000 rpms than at idle? Just curious if an alternator upgrade would improve that at all, or if it's another phenomenon.

This system really does sound brilliant ... unfortunately it's sort of lost during the summer because I have to drive with the windows down as I have no AC. For some reason, boomy, crappy sound is easier to hear over the rush of wind and traffic, whereas the crisp, bright sound seems to get drowned out. Maybe I should fix my AC ...

BoomInTheTrunk · #2 08-16-2009, 07:57 PM

Do the Big 3 upgrade and see if you see a difference. Upgrade the ground to a 0 gauge and run a 0 gauge wire from the alternator to the battery terminal then run one more ground to another location on the motor some where. It will possibly keep the electronics from dimming and help at the lower RPM's of the motor.