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Car audio speaker impedance and wiring dilemma

wheresmybacon

wheresmybacon

Diamond Member
This may be a really bad or weird idea, but I figure I'd ask. Also not sure if this should go in The Garage or here, so mods please move if this post is in the wrong place.

I'm putting a system together and I have Infinity Reference 6030cs separates in the doors of my 2003 M3. Manufacturers specs indicate that each one of these is a 2 ohm load.

Since I'm on a budget and am not too concerned about rear fill, I'd like to use the Harmon Kardon mid and midbass drivers that I already have in the rear of the car. Each of these speakers are 3 ohm.

Again with budget and parts already-on-hand in mind, I have an oldschool Rockford Fosgate Punch 75 I'd like to use to power the entirety of the system sans the subwoofer. For my sub I have a Rockford Fosgate P325.1.

On to my question! I'm trying to figure out a way to wire each channel. Here's what I'm thinking, but I'm not sure it that will work or not.

35OhmLoadonPunch75.jpg


Admittedly I haven't done an install in a while, and I certainly haven't monkeyed around with 3 ohm speakers before. Is this even a viable solution? Or should I just wire them in a series, getting 8 Ohm? I'm open to ideas. I don't want to buy new drivers for the rear as if you've ever been in an M3 you know the rear seats are really an afterthought.

Thanks in advance.
 
I assume you're going to have a crossover in there somewhere, that will affect the total system impedance for any given frequency. You really want to wire up the speakers as they were designed to be connected with the crossover or else you'll have all kinds of problems. I'd suggest running the front speakers off the punch 75 amp and connect the rears to the integrated amp in your head unit.
 
Your assumption is correct. The loads represented in the image are inclusive of the crossovers/etc.

I like your idea about the head unit. I'll just do that. Thanks!
 
Why would you use speakers in the rear at all? If its really just for "rear fill" (which is really just "Screw up the soundstage and have sound coming from behind you that is supposed to be coming from in front of you for the sole benefit of your rear seat passengers") Just use the unused channels out of the head unit. Your rear seat passengers are the only ones to benefit from rear speakers, and thats more than enough to hear what is going on.

This is also a terrible idea (using multiple full-range speakers in multiple locations in a sound-stage without time alignment or phase correction). Basically - the sound from the front and the sound from the rear speakers arrive at your ears at slightly different times. Also the sound field generated by the speakers create both constructive and destructive interference. The most apparent effect is that your speakers just don't sound right, and you can't put your finger on it. Things become hard to pick out, details get lost, sound is just plain muddy.

TL;DR
1. Stick with just using the fronts.
2. If you must use rears, just use the amp in the head unit.
 
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