View Full Version : Head unit and Speaker selection

08-01-2007, 09:21 AM
I'd like to upgrade my OEM (2002 Galant) head unit and speakers. The existing size speakers, head unit are as follows;

-Head unit is DIN size
-Front speaker location and size: lower front door panel, 6.5"
-Rear speaker location and size: rear deck, 6x9

I would like to use the existing speaker locations without external amp. What information is needed so components complement one another. Do the aftermarket speakers and head unit have to match my OEM head unit and speakers (ohns,watts etc.) due to existing wiring? If not, how do I select aftermarket head unit and speakers?

For example, I've been researching a head unit I like with the following specs;
-Maximum power output 212 watts (53W 4 Built-in MOS-FET Amplifier) 20 W RMS x 4 channels at 4 ohms
-Speaker Impedance 4 ohms (4 ohms to 8 ohms allowable)

6.5" speaker specs (front);
-2 way design
-tweeter design is 1" dome
-sensitivity is 92db
-frequency response is 46 - 21k Hz
-RMS power range (watts) is 2-100
-peak power handling (watts) is 300
-Impedance (ohms) is 4

6x9 speaker specs (rear);
-2 way design
-tweeter design is 3/4" dome
-sensitivity is 92db
-frequency response is 53 - 21k Hz
-RMS power range (watts) is 2- 60
-peak power handling (watts) is 180
-Impedance (ohms) is 4

Will this head unit and speaker combination work well together? Also, with regard to selecting head unit and speakers, do all components need to be the same impedance? All 2 or 4 ohms, or can the head unit be 2 ohms, rear speakers be 4 ohms and front speakers be 2 ohms?
Your help as well as your time is appreciated.
Thank you.

08-01-2007, 09:33 AM
Welcome to the forum. Hopefully your time here will be well-spent.

First let's cover a couple of basics:
Wattage ratings, whether those ratings are related to the output capability of an amp or the input capabilities of a speaker/subwoofer, are generally given in two sets of values ~ RMS and either Peak or Max wattage.
When you encounter wattage figures listed as Peak or Max you can take these figures and completely ignore them altogether. Sadly they are basically useless numbers good for nothing more than marketing purposes.
What this leaves is the RMS wattage ratings which is a much more important number. It is the statistic that is indicative of *whatever product's* capabilities in real-world, day2day use.

When considering aftermarket speakers - whether they be coaxial speakers or a component set - can certainly work if only being powered from a headunit but you won't be able to extract all the performance they are capable of without using an outboard amplifier of some kind. Headunits simply do not offer sufficient output to get all of the performance possible from even mediocre aftermarket speakers.

"Ohms" is the unit of measure for electrical resistance. You aren't going to change the ohms of a headunit - pretty much every aftermarket headunit in existence is designed to operate with a speaker load resistance of no lower than 4 Ohms per output channel. Ergo - should your aftermarket speaker purchase be of the 2 Ohm variety you don't want to try powering it with the headunit. Unhappy things can and likely will result.

I've got more to say on this subject, certainly, as it's a broad one, but I need to step away from the PC for a few minutes.
I'll be back!!

08-01-2007, 12:21 PM
Hello Prowler573 and thanks for your reply, it's appreciated. At this time I was considering the following head units;
-Clarion DXZ775USB
-Pioneer DEH-P6900USB

6.5 oversized or 6.75 FRONT SPEAKERS
-Infinity Kappa 63.7i (2ohms)

6x9 REAR SPEAKERS (already in place)
-Infinity Reference 9612i

Would like a set of three or four way speakers (Pioneer TS-A1682R ?) for front location with impedance of 4ohms to match all components. Any recommendations? I'll await your return and adding to your post.