OK, guys, don`t laugh. I`ve done alot of wiring in my time (i`m 19) but one thing I just can`t seem to comprehend: Ohms. I know wiring has alot to do with it, but please break it dow a little better. Any help would be great!

 

ohms is resistance. Higher ohms=more resistance. Lower ohms make for more efficiency. Help? You can go to www.the12volt.com if not.

 

Ohms/impedence is the resistance of a component to the flow of electric current. Impeadence is an "active state" resistance, ie, the current/voltage is alternating like on a speaker or a toater oven at home. Plain old resistance is a "static state", ie, DC condition like the rear window defroster wire or the resistors in you car fan control, or the light bulbs in your truck.

Higer resistance will allow less current to flow and cause a higher voltage drop across the component. Since autos are limited in the amount of voltage available, we are seeing a lot of amplifiers etc that are capable of driving more current at the same 12 volts. This is why you are seeing 4 and even 2 ohm speakers versus the old 8 or 16 ohm speakers. The lower resistance allows more current and since power is current times voltage, you get more power. This is also why we are seeing talk about autos going to something like 42 volt systems in the future so they can supply more power for all the computers and accessories we want in our cars. We can't boost current as easily since wires get too fat for lower resistance and so they don't melt, so voltage boost is the way to go.

Resistance can also be bad. If you have high resistance/impedence wires you will get more voltage drop in the wire and supply less to the component. For example, if you have 4 ohm speakers and your wires have 4 ohms impeadence, you are loosing half your potential voltage just in the wires. Ditto for your starter motor, that is why starter motor wires are really fat, you can't afford to lose any voltage in the wires.

As a quickie...

Resistance = Voltage/Current
Voltage drop = Resistance x Current
Current = Voltage/Resistance
(low resistance means more current)

from that we get

Power = Voltage x Current = Voltage x Voltage/Resistance =
Current x CurrentxResistance

Hope that helps.
Jim Henderson

 

OK, thanks guys, that helps alot. I am finishing up a speaker box to house two 12`s with a two channel amp. What is the best way to wire it up? In a series or paralell? or Should I just hook one up to each channel?
Thanx for the help!

 

prolly just hook each sub to one channel
assuming you have normal 4ohm subs
if you wired them together in series, you'd have an 8ohm load, most amps are designed for a four ohm load, so your wattage would get cut in half.
if you wired both subs in paralell, you'd have a two ohm load.
most amps these days can handle a 2 ohm load on each channel, but when you bridge an amp each channel only sees half of the total load, so with the subs in paralell each channel would be driving a one ohm load. some amps can handle one ohm, but most cannot, and may blow.
so unless your amp is rated to drive one ohm(and some are) I'd run the amp in stereo.

 

Sweet.. I in fact do have an amp that will run at 1 stable ohm..... This really helps alot, thanks!

 

OK disregard some of the last post
wire the speakers in paralell, and bridge the amp

sounds like you're in for some THUMPIN