Also I got this for you from Crutchfield as well:

"Impedance
The resistance offered by an electric circuit to the flow of alternating current

 

Whoa I am still confused. I was wanting to run x-over 2 channels for the sub and the other 2 channels to run my door speakers. Would that work with the Polk Sub?

 

If you want to keep it simple (minimal parts)

I'd buy the the Dual, 2 ohm voice coil Sub

Hook each coil to ONE rear channel of the amp and use the internal low pass filter on the amp for the rear channels.

You already have a variable bass boost on the amp that controlls the rear channels ONLY, so perfect for your application.

 

Get the DB124(4-ohm) and bridge the rear channels if you want to get the most power out of this amp. It probably won't be stable bridged @ 2-ohms.

 

You yell'n at me?

Ok, sure, bridge it to 3 channel (same rated power output @278 watts either way), but I'd still get the DVC (at 2 ohm) for future expanability/flexibility. Wire the coils in a series for a 4ohm load.


Don't forget to start using the high pass filter on the amp for the fronts once you get the sub going.

 

You would want to use a 4 Ohm subwoofer. Read http://www.bcae1.com/bridging.htm under the section titled, "Why a 2 Ohm Mono Load May Damage Your Amplifier." In the picture at the end you would correspond to configuration Y, also look at Diagram D on that page. Since we know that for a single channel the amplifier impedance is 2 Ohm (evidenced by a higher power output from a 2 Ohm load vs. the 4 Ohm load) and since you are essentially placing two voltage sources in series along with their corresponding impedances, and that's where the 4 Ohm comes from in bridged, 2 from each channel.

Basically, if you bridge 2 channels use a 4 Ohm load and if you just use a channel normally use a 2 Ohm load. Just like I said above.

You could also run two 2 Ohm subs in series from the bridged channel to get your 4 Ohm load, but I am assuming you only want one sub based on the lack of "s" following "sub" in your posts.

And I never said that I trust Crutchfield, I just trust their data entry people to be able to read a data sheet and type what they read. Did you even look at my first link? Since Power = Current^2 * Resistance, there is a point where lowering resistance to have more current flow actually lowers the power output since you have lowered the other factor, resistance. The point of maximum power transfer occurs when you match the load impedance to the supply impedance.

That quote from Cruthfield is false since they don't reference that it would be for a 2 Ohm supply, if the channel had a 4 Ohm supply side impedance then a 4 Ohm speaker would get more power. Just look at http://www.allaboutcircuits.com/vol_1/chpt..._power_transfer again.

 

It's a dual 4-ohm. You either get a 2-ohm or 8-ohm load. Neither of which are ideal for getting the most power out of the 2 rear channels of that amp reliably.

 

Good call Jason.......your're right the DVC polk Sub has 2, 4ohm Voice coils......I missed that.

Jeff if you have to have polk....get the single 4 and bridge the amp.

 

burnmacs - I'm not going to argue with you... Your right I'm must be wrong. Happy now...
Your an engineer you 'must' be right and I must be wrong.

 

I'm happy to be shown incorrect and even will admit to my mistakes and appreciate being corrected, I just need real evidence to back it up from real sources. I was trying to not only tell the guy what sub he wanted, but explain why. That way we can sort through myths and when people use the search they can take the concept and make informed decisions when they plan their own system and not have to just see "wired correctly". I provided two links that explain on a base level of math & physics why my opinions are as such.

Since the power output is higher for a lower load, the supply impedance will probably be 2 Ohm or less. If it were less, you want to match your load to that. If the supply side impedance of one channel was 1 Ohm, bridging them would yield a 2 Ohm supply side impedance and thus maximum power would be from a load of a 2 Ohm speaker. Since the supply impedance value is not always known and is even possibly dependent on frequency, I linked to another site that explained why using a 2 Ohm speaker may be bad on the bridged amp since each channel may be designed to drive a 2 Ohm load. Given the amp doesn't even give a power spec for a 2 Ohm bridged load, my guess would be that you don't want to do it.

I'm not sure why you feel the need to use the , I was professional in all of my posts. I even made sure my first link referenced the concept to the application of audio instead of being pompous and just referencing the concept and expecting others to understand it.