[font size="1" color="#FF0000"]LAST EDITED ON 23-Oct-01 AT 03:22 AM (EST)[/font][p]My used, '97 Expedition, Eddie Bauer which has the factory-installed MACH System, Premium AM/FM/TAPE + 6CD-Changer. I've been pleased with the system overall, BUT...

Passengers complain regularly of hearing "too much bass" and not enough mids/highs in the third row seats.

This is true when playing CDs, the radio or tapes. It seems that the mids/highs coming from the four doors towards the front of the vehicle just get lost in the back...

Is there any way to improve the frequency balance (and apparently deficient layout/design) in the third row without dialing out the bass altogether?

I'd be willing to consider installing another pair of speakers in the rear wall panels, if it would help (and if it's possible.)

Help!?

Thanks,

Marko

 

Marko-
The problem you describe is what I would expect with the speaker layout in the Expedition. As you have already found out, the sub is in the back and the speakers are in the doors. Bass is pretty omnidirectional, so it can be heard throughout the truck, but the higher frequencies can be heard best near the speakers.

You could (best option IMHO) install speakers in the back, but you would probably have to take a speaker level signal from the rear speaker wires and run it through a line converter to an external amplifier. This doesn't give the best sound quality in the world because any distortion from the existing amplifier gets amplified again in the aftermarket amp, but it shouldn't be a big deal at normal volume levels. The Ford factory amplifiers seem to put out a surprisingly clean signal, although there isn't a whole lot of power output.

You can't use the Mach radio's preamp outputs with aftermarket amps because of signal incompatibility. You could relocate the door speakers, but then you have the problems in the 2nd seat.

If you try to tap into the rear speakers and have the factory amp drive all four back speakers you may run into problems with the amp not powering up and thus not getting any sound at all. I know the 1999 and up radios with the internal amps (right in the head unit) do a resistance check on the speakers before powering up (to check for shorts in the wires). If you put two more speakers in parallel with the existing rear speakers, you will cut the resistance of the circuit in half. This may (I'm not sure what the tolerances are) cause the amp to trip out. If you take out the rear speakers and install four new speakers with twice the resistance of the factory ones, the resistance will be the same and the amp should work fine, but you will cut the power delivered to the speakers in half (less volume). Your best bet would be to hook up two more identical speakers with the rear speakers and see if the radio powers up. If so, then there shouldn't be any problems, unless the amp overheats (this setup will increase the power load on the amp by 50%).

One more idea is to scrap the idea of putting in any passengers in the back seat at all (it's pretty uncomfortable anyway). Remove the third seat, and replace it with a plastic tub. Then put a barrel of beer in the tub, fill it with ice, go to the lake and have yourself a kegger party.

Jerm

 

I guess I should try that BEFORE the kegger party...

Could I try to do something somewhere inbetween that would increase the load a little less? For example, install two more, new speakers in the rear with more than half the resistance of the existing rear speakers (tapping into the amplified signals that are going to the rear speakers?)

Anyway, thanks for the great information!

- Marko

 

First of all. have you personally taken your exp. to a stereo shop to see what they say. I'm sure that they have dealt with this problem before. Obviously when ford designed this they were thinking of the front two rows. Why? because generally you aren't going to have a car load of kids riding down the road with the radio blarred. I would suggest that you remove the rear subs, put some quality mid range speakers in the back that way the sound is then equalized. And then I would tap into the left signal(+) and the right signal(-) and then bridge them with a very nice amp with a built in crossover that won't allow any feedback. As for reading the guys last explanation i'm not sure if this is possible. I have never personally dealt with a system like that. As for the signals not matching up on the fords rca preouts, I'm sure that they have some kind of device that will change it back to standard format. Not sure though. Just an idea. You're best bet is to go to a store like car stereo city or car toys.