New rear door speakers-no bass! - PeachParts Mercedes-Benz Forum

miktvk · #1 11-08-2002, 08:27 AM

ok, now I'm sad. I installed the awesome Rainbow SLs in the dash from the fine folks at LaJolla, that made me very happy.

So happy that I went ahead and installed some Alpine 3.5" SPS-0829s in the location in the rear doors (this is a '95 E320 wagon). They produce fairly clear sound, but zero bass, and at higher volume I can detect some distortion. What the heck happened??

I though this would be a simple plug-n-play considering the low-power requirements of the Alpines, but I guess I was wrong.

Unfortunately, I don't have the original radio manual that came with the car, that might have provided some guidance, but I thought this would be a no-brainer, apparently its me with no brains.

I'm no audiophile, I just want improved sound in the old wagon.
Anybody have an idea what to do?

Thanks!

JCE · #2 11-08-2002, 08:44 AM

3.5" speakers are not going to put out much bass - they don't have enough cone surface or driver movement to move much air, which bass wavelengths require. In fact, they generally need a high pass filter - something to cut out the bass frequencies - to keep them from distorting at high volumes. If you want bass, 6.5 or 6x9 are where you need to start.

miktvk · #3 11-08-2002, 08:55 AM

But, I'm not looking for a massive amount of bass; the new Rainbows (approx 4.5") in the dash pound out a fair amount, especially relative to the factory cones I removed.

The Alpines just sound like something is wrong with the system, neglibile bass response; less than the stock paper cones I took out.
I'm stumped.

We briefly owned an Audi A6 with the top of the line Bose system, and that was absolutely the best factory sound I've ever heard, so I have something in mind for comparison, although it doesn't have to sound that nice.

JCE · #4 11-08-2002, 10:13 AM

You might check over the installation a bit. The speaker should not be overtigtened to the cut out in the door frame. There should not be any holes or gaps around the speaker where it attaches to the cutout, as this will allow sound waves from the front to distort and cancel when they hit the back surface of the cone. Speaker wire polarity should be observed for both speakers. There should be a reasonable volume of space behind the speakers. A bass blocker type low pass filter - about 120 or 150 hz for a 3.5" speaker - will help prevent distortion.

If everything checks out, maybe the speakers are bad, but the sound from 3.5" speakers in the rear is going to be pretty directional into the rear of the car. Also, the 4.5" rainbows have 50% more surface area than those 3.5 Alpines, and are going to move 50% more air, and have more bass capability!

So the speakers may be bad, or the installation may need some tweaking, but most likely the 3.5"s aren't up to the job. FWIW, the Bose systems had a sub driver, and since the bass frequencies are relatively omnidirectional, a sub sounds like it is coming from throughout the car. The higher the frequency, the more directional it apears to your ears.

miktvk · #5 11-08-2002, 10:32 AM

Thanks for the info, John,
Polarity is definitely correct, but giving it more thought, based on what you say, I think there is just not enough open space behind each speaker, they are mounted inside the arm rest, away from the hole in the sheet metal behind, which is actually not big enough for the magnet; just a bad environment to generate any low frequency.

Holson Adi · #6 11-08-2002, 06:51 PM

What size speakers were originally in there?

3.5?

You could probably fit some 4" Inifinity's in there...

Anyway I must agree that the Audi A6 with its Bose sound system sounds amazing. Better than the C230's Bose, and the BMW 323Ci's Standard stuff.

SCLJA · #7 11-08-2002, 10:03 PM

The three things that are going to cause the speakers to sound bad are not being sealed into the enclosure and the lower frequencies distorting the speaker and the size of the speaker. This location was a terrible afterthought at mercedes. I am sorry I don't have an easy fix for you! Enjoy your new front speakers

Scott@lajollaaudio

miktvk · #8 11-10-2002, 10:01 AM

Hi Scott,
Thanks for responding. The 3.5s were definitely not sealing well, so out they came and in went some 4" Eclipse, they have a square-shaped, 4-screw mounting flange around the cone that seals that area up nice and tight. No distortion seems to be present.

I only had to shave a little plastic here and there to make them fit, no problem.

It's just a bad location, a bad design and engineering compromise.

SCLJA · #9 11-11-2002, 10:06 PM

I am glad that worked out for you! Do you have a pic of the install?

Scott@lajollaaudio

miktvk · #10 11-12-2002, 07:41 AM

I'll get one for you Scott, no problem!