mattski

Hiya,

Firstly, the car isn't a scoob... but you chaps know your stuff anyway so here goes...

The car is a 96 Mercedes E320 and I've kinda decided to upgrade the stereo in it so have so far got the following:-

Kenwood KDC-PS9590R cd headunit
MB Quart two-way (with little crossover) things in the rear doors.
Infinity two-way components (with crossover) in the front doors.
standard mercedes speakers in the rear shelf ( to be replaced ).

I think it sounds fab but... when playing a fairly bass-heavy track at high volume the headunit can really loose the plot, it starts to distort and 'fade' (best way I can describe it) until the volume is turned down etc.

Now I know what you're thinking, it's too loud. BUT... it is 'loud' but sounds fine at the same volume, it only starts to loose it after a while, as if something is getting hot perhaps?

So, what do you think... Is it the headunit not being able to cope ( should do, it's fairly powerful ), 'odd' speaker loading with all of those speakers dotted around? dodgy head-unit ?

I've got an amp to go in (5 channel Alpine V12) but am a little concerned about the headunit at the mo, or should I just turn the volume down

One more thing... there are speakers in the rear door and rear shelf, how does front-rear fading work in such a situation? Are the rear door speakers simply wired to the rear shelf speakers?

ta,
Matt

chiark

Ooh err, I'm guessing here, but I think you'll be running two pairs of speakers off one channel pair of the head unit. This is meaning that the head unit is trying to drive a 2 ohm load, which it shouldn't do at all

This is assuming that Mercedes haven't put some form of balancing trickery in circuit, but I really don't know. Have speakers always been in the rear doors?

Anyhow, assuming no special tricks, driving a lower impedance load than 4 ohm with a head unit will cause two things: more distortion, and more heat.

I'd guess that as the heat builds, distortion becomes worse.

I'd use two channels of the amp on the front speakers, two on the rear shelf speakers and disconnect the door speakers. Move the MB stuff to the shelf. Then with the spare channel, run a sub for your basslines

mattski

Hiya,

Thanks for the reply... it sounds like what you suggest could be right, although I am not sure how they will have wired it. The speakers have always been in the back door. I tried fading to the rear but the back door speakers where still on a little.


Anyhow, assuming no special tricks, driving a lower impedance load than 4 ohm with a head unit will cause two things: more distortion, and more heat.

sounds fair... so would you disconnect the rear shelf speakers?

I'd use two channels of the amp on the front speakers, two on the rear shelf speakers and disconnect the door speakers. Move the MB stuff to the shelf. Then with the spare channel, run a sub for your basslines

The MB stuff won't fit into the rear shelf, it is too small! The speaker layout is as follows:-

Front : 6 1/2" in the door, tweeter in the corner of the door. (some have a 3" midrange in the dash).

Rear Doors : I *think* it's about 5"

Rear Shelf : 6 1/2" although there is holes for an extra set of 6 1/2's !

The way I am thinking of doing it was like this:-

Infinity components in the front.
MB's in the back doors.
Nothing on the rear shelf.
Focal sub in the boot.
Alpine V12 5ch driving it all.

Would you go for rear shelf or rear door mounting?

ta,
Matt

chiark

Which mounting to choose? Oh it'd be too easy to insert a crap joke, so I'll cut to the chase

I'd go for the doors if you have to, and then leave holes on the shelf (covered) to get the bass out of the boot.

Sounds like it will be a nice system