ok i have to 4 ohm speakers and a 2 channel amp that is 2 ohms of output on each chanell(bridgable to 4 ohms) how do i wire this?

 

The only way you can is to wire each sub to its own channel. Ir just use one subs and bridge the channels together.

 

ohm education.

"ohms" are units of resistance. Just like inches are units of length.

Resistance is what prevents infinite amounts of current from travelling through something. For example, if you short out your battery wires, you have a situation where there is "zero" resistance between them. Bad things happen. The output of your amplifier is basically the same thing. The lower your impedance, the closer you are to a direct short.

Your amplifier can only deal with so low of an impedance. In your amp's case, it's rated to be able to deal with 2 ohm loads on each channel. Your subs are rated at 4 ohms each (although that's another issue all its own). If you hook one sub to each channel of your amp, your amp will be happy.

A common thing for people to do is "bridge" an amp. This is when you use both amplifier channels together as 1 channel. Most car amps have this capability. When you do that, each one of the 2 channels sees 1/2 the impedance. That means that a single 4 ohm sub hooked to a bridged amp places a 2 ohm load on each of the 2 amp channels. This is why amps are typically specified as "stable 2 ohms stereo, 4 ohms bridged", because that "4 ohms bridged" places a 2 ohm load on each channel, just like the 2 ohm stereo configuration would.

So... on to wiring subs. There are 2 ways to wire speakers together. One is "parallel" wiring and the other is "series" wiring. Since it's a pain in the *** to describe it, I'll just use pics that I swiped from JL Audio's site.

Parallel:


Series (this shows 1 dual-voice-coil sub, but wiring 2 single coil subs is identical):


With 4 ohm subs, parallel-wiring results in a combined 2 ohm load. Series wiring results in a combined 8 ohm load.

So... why would people want to bridge their amp and/or use lower impedance subs? Simple. The lower the impedance is, the more power the amp typically makes. This is due to Ohm's law (and you thought the term "ohm" was just picked randomly), which states that power equals volts^2 divided by resistance. Since you can't change the voltage on the output of your amp, changing the resistance is your only option. But... the amp can only deal with so low of a resistance before the current output exceeds its abilities.

So... let's combine all this crap. If you bridge your amp, and try to drive your 2 subs that are wired in parallel, your combined sub impedance will be 2 ohms, which means each amp channel will see a 1 ohm load. Your amp isn't capable of doing that.

Your next option is to series wire the subs for a combined 8 ohm load. This will place a 4 ohm load on each amp channel, which is fine. But... there is absolutely no benefit to wiring it this way compared to just keeping the amp in stereo (unbridged) and running 1 sub off each channel.

clear as mud?

 

I kinda want to hear what my new mids sound like. It'll be a week or so until they get installed in the car. They're 4ohm speakers. Can I run them off my home 8ohm stereo amplifier, or would that wreck something?

 

yes, it will wreck the amplifier.

connect the pair of 4 ohms in series +-+- , connect the + of one speaker and the - of the other speaker to the - & + of ONE channel.

Two 4 ohm speakers in series is 8 ohms and this won't hurt an 8 ohm amplifier.