View Full Version : Upgrading Head Unit To Better Factory Unit

02-11-2010, 06:28 AM
Hi all,
Right, here's my dilemma. I've got a 2004 Ford Fiesta Finesse, and I want to upgrade the speakers. Because of certain ownership limitations, I can't really change the head unit to an aftermarket one, but I still want to get good sound out of the car.

I am going to replace all 4 door speakers and run them off of the head unit's internal amp. I am also thinking of getting an active subwoofer and connecting it through the ol' splicing one of the back speaker wire trick.

The only thing I'm thinking about, is because the new speakers would be able to handle more volume than the stock ones, and they could handle more bass (until I got the sub anyway) the head unit amp could be under a lot more strain? Would I be in danger of blowing it?

Thanks in advance for any replies,

02-11-2010, 06:55 AM
You can't swap out head units, which requires no cutting of any factory wires, but you can splice the back speaker wires to add a sub? :confused:

You won't blow the internal amp if the speakers you buy are 4 or 8 ohm. If they are 2 ohm speakers, there is a good change you will cause damage to the internal amp.

Honestly, unless your factory speakers are blown, they will probably sound better than if you replace them with aftermarkets, solely because aftermarket speakers need the power only an amplifier can produce to sound good, 90% of the time. Especially in newer cars, which come with pretty decent factory speakers.

02-11-2010, 07:05 AM
Thanks for the reply. I understand what you're saying, but the speakers in the car at the moment are very weak, and when turned up to a reasonable volume you can't have the bass setting up too high or they distort. The overall sound is muddy, so hopefully new speakers will improve that. Regarding the power bit, would it be possible to join both the front and back wires into 2 speakers, giving them double the power? Would this be better than using 4 speakers? I'm not familiar with the kind of outputs a generic head unit has, but if it came down to it I would be happy to get an amplifier for the door speakers if I could still use the standard head unit.


02-11-2010, 07:10 AM
Unfortunately, no; you cannot bridge a head unit.

Yep, with Line Output Converters. They convert the speaker leads to RCA outputs. But of course, this requires cutting the speaker wires to your head unit, so if you need to return the vehicle, that would be an issue...

Line-Out Converters | Line Output Converters at Sonic Electronix (http://www.sonicelectronix.com/cat_i331_line-out-converters.html)

02-11-2010, 08:20 AM
I didn't think I'd be able to bridge them. I'm used to using large outboard amps, being a sound technician and all, but I've never really ventured into the world of car audio. I think what I'll do is wire the new speakers into the headunit amp to start with, and see how they sound. If they need any more oomph I'll do what you suggested. One thing that I have read somewhere is some factory stereos limit the bass at higher volumes to eliminate distortion with the cheapie speakers. The stock stereo does have bass and treble controls, I'm guessing I'd just have to experiment with them if I got a sub?

Cheers, Chris.

02-11-2010, 08:32 AM
I've never heard of such a thing, but I've never ran aftermarket speakers off of a factory head unit.

If you got a sub though, it probably wouldn't matter too much, considering you'd have an amp to power it.

02-11-2010, 08:57 AM
Well it would be an active sub, so the amp is built into the enclosure. I'm guessing it just takes the signal and uses its low pass filter to channel out the rest of the frequencies?

02-11-2010, 09:01 AM

02-11-2010, 09:14 AM
Excellent, I think I'll order some speakers now :) Thanks again for your help mate, much appreciated. Have a good day!


02-11-2010, 09:19 AM
No problem dude, good luck. :)