Thursday, November 27, 2008

More power?

Unlike in Star Trek more power will not get you what you want. Why? Well for instance you could push 10,000 watts into an 4 ohm woofer, but it would fry in under a second, even less for 2 ohms. You see you want voltage, not current. The voice coil of the speaker is what makes the cone move up and down. Almost all subs use 20 gauge or smaller wire. Now how much current can 20 gauge sustain for an indefinite period of time? About 10 amps. How much voltage? About 200 volts. See where I'm going? Why did I use an 8 ohm sub in my car? Well my 8 ohm sub will soak up 60 volts at 7.5 amps. That's 450 watts RMS, 900 peak with an oscilloscope. Most subs can't play at 60 volts before breaking. However my can because of the high resistance. Because my sub puts out 107 db at one watt it requires very little power to operate. So at 450 watts I can put out 134 db. If you take that POS kicker which 88db efficient and put 450 watts into it you will get 115 db. Big fat freakin' difference eh? And there is also a limit to every subs maximum output potential, you will have a hard time finding it unless a. Your sub is a pro audio driver, in which case it's in the spec sheet. Or b. You will have to contact your speaker mfg to find out what it is. Most of the time the mfg will not want to state it because it is a rather low number. Now I know what I just said above probably rattled your brain and you have some questions, like "but my friend down the street has a kicker solo l17 and it sound loud." Yes it may sound loud but a bet you a 1000 bucks he can't play it that loud for very long, I've tested my sub at 50 hz at 60 volts for 48 hours, my sub never broke, and my amp stayed room temp (ap1200). His will most likely overheat in a few hours. Also when looking for a good amp go with a high RMS rating at 4 ohms, believe it or not, stay away from mono sub amps. They are meant to run at 2 ohm's which is cheating by allowing more current rather than voltage, current is easy, just make the wire on the transformer core larger, voltage is more difficult you need to wind more wire, 60 volts output (at 12 in) is a 1 to 5 turns ratio. Now typically high voltage does not mix with high current (low resistance) which is fine, I like my 8 ohm sub which actually halves the THD.

Wednesday, November 26, 2008

I promised I would upload images of my car:

Tuesday, November 25, 2008

Emergency Unlock

Have you ever found yourself in the situation where you leave your keys in the car? Or even worse you have the engine on and the doors locked, but your are outside? I have. All this and even worse (like leaving the baby inside the car), can be avoided with what I just did. I took the unlock wire (which is actually a ground wire) and made a junction to another 10 foot 20 gauge wire, then I soldered the wire to a momentary push button, then another wire to a ground point on the chassis. With this I can put the push button anywhere under the vehicle (right now I have it 2 feet off to the left of the engine block). So if you leave your keys in the car as well as the family dog and the baby in 110 degree heat you can just slide under the car push the hidden button and unlock the doors. This can be a real lifesaver if your forgetful like me. I will post pictures in the morning.

Locked out, again

Well this was bound to happen, about a week ago I had to reverse the door handles because KIA in there infinite wisdom decided to make the door handles COMPLETELY out of plastic. Even the receiving ring for the locking bar. What does this mean? This means I need to go down to KIA pay 60 bucks for each door handle and have them replaced. Scam eh? So after using my neighbor's Slim Jim to get into my car I took the paneling off and rebuilt part of the handle, simple job. Now the receiving ring is screwed in place and it's made of a metal washer, this should keep from breaking off, one down three more to go..... I will be posting pictures of my car later on today. But right now I need some sleep.

Sunday, November 23, 2008

Alt doing good so far

Well the new Alternator in my car is doing great, it starts off at 14.4 volts and drops down in-between 13.4 to 13.8 volts when the battery is charged/car is hot. wich is nominal I used my 200 amp current meter and it actually shows more current when the alt is hot (13.5 to 13.8 volts) about 175 amps, but that is to be expected at the voltage is lower. This is a 3g alt s othe voltage tapers off when the battery is charged and it can whip out 122 amps (13.5v) at 800 rpm engine idle. This is probably the best alt I know of. Also when the car is hot and the voltage drops the voltdrop from current draw is smaller (100 amps at 14.4 drops down to 13.4, at 13.4 it drops down to 13.2) this right here tells me the alt is doing peachy. Hopefully next week me and Bracket Man can take off the front end of my car and get a larger belt so I can use the H bracket he made. I keep forgetting to take pics/videos of my car. Tomorrow I promise to take some pics.