Anyone know/see a real difference in using factory speaker wiring versus running your own cable?
I am looking at finally adding an amp so I can get rid of my HU. Amp is only about 100w RMS x2.
Play with it, 'til it's broke.
I have a tad bit of experince in the subject.
What is the application, to drive door speakers or a sub?
One has to ask themselves, are you going to continuously push that 100W amp to its limits? Pushing a typical door speaker to 100db (that REAL loud for a door speaker) can be done with approximately 32W. Driven into a 4 ohm load that is 2.8A. Chances are your vehicles speakers are wired with a minimum of 20ga cable, probably 18ga.
Even if you had 20ga cable. The resistance of said cable is approx 0.08ohm per foot. Power loss across a cable run of 12ft would be 7.5W. Not trivial, but, not terrible. things improve with 18ga cable. It's resistance is 0.06ohm per foot. Power loss along the same wire run is 5.6W. Now, lets put things into perspective. Say you had the ambition to rewire your system with 16ga cable. This cable has a resistance of 0.04 ohm per foot. Power loss down a 12ft cable would be 3.8W.
There will be no appreciable power loss across the stock cable. The difference between 20ga and 16ga cable may gain you 0.5dB or so in additional output. Your ears aren't that sensitive. Therefore, keep it. Statements suggesting you'll get better SQ are silly. The cable adds no distortion or frequenct response anomalies to the signal. The only difference being where there is a grosse undersizing of cable. Where attenuations of 3dB to 6db are encountered. The human brain seems to equate louder to sounding better since your brains sensitivity to various frequencies starts to flatten out as volume increases. Music sounds more natural.
Make sure you use at least 18ga cable to prevent excessive power loss. Subs are much less efficient than door speakers and require more current to get them going. You need to achieve higher sound pressure levels with a sub to make it sound as loud as door speakers. This is because your ears are less sensitive to low frequencies. You may need 120db out of a sub to make it sound as loud as 100db from a door speaker.
I hope my mindless drivel has helped you decide.
I am driving some Pioneer 3-way door speakers... nothing too crazy. I actually tested one of the speakers with this amp by splicing into the factory harness... and it sounded fine. Hard to tell with only one speaker going, but I think it will work out.
And yeah I should have done the math in the first place. Ohm's law is <3
Thanks for such a good write up!