4 + 4 Ohms =......I'm not sure
 

Well the linear DC answer is 2 Ohms......but... I am pretty fair electronics person and I know when to ask and take advise. I have a pioneer head unit in my car and am driving my crappy rear speakers (one on each side) directly from the head unit( Pioneer like I said)
I ordered a set off the metal rear speaker brackets to replace the Porsche Plastic ones in my car and going to ditch the cheapo speakers. I just got in 4 of the Polk DB351 that fit the brackets like magic. They are listed as 4 Ohm each.....so the real question is parallel or ??

Thanks in advance

Dwight

Driving each off of a seperate channel, 2 on one channel or 4 on one?

For 2 per channel, go with 2 ohms (parallel).

Two
 

Two channels in rear, each will have 2 - 4 ohm speakers in it. 4 total speakers. No amp just the power from the head that is well under the power rating for the speakers

Yeah, I'd go with parallel, assuming the HU is 2 ohm stable.

Either way will work but it makes the most sense to wire in parallel. Rear speakers are small and won't demand much power that you will have a stability problem at two ohms.

I've got 4 2.75" speakers in the rear, in parallel, driven directly with a cheepo JVC BT head unit. No problem.

Now that I think about it, Last year I added the door speakers to the rear channels as well ( in parallel). No issues.

Next question
 

are you guys using the supplied capacitors as a passive crossover or just wiring them straight ?

According to ohm's law; if your speakers are 4 ohms impedance

in series : impedance adds up = 8 ohms

in parallel : If the two resistances or impedances in parallel are equal and of the same value, then the total or equivalent resistance, RT is equal to half the value of one resistor so roughly =2 ohms.

rule of thumbs here say to match as close as possible the HU impedance.