tricking amp with speaker's impedance

i have an amp that puts out 400watts at 2ohms. i am thinking of a jl10w7 which is rated for 500rms and has a 3ohm voice coil. is there any way to "trick" the amp into thinking that there is another sub that doesnt take any power? i would assume that there isnt but a lot of you guys know much more than i. also, with the amp i have, will the w7 be able to put out as much volume as a w6 would?

Just run it at 3ohms. The small increase in power you'll get won't make much of a difference. Remember, you need to DOUBLE power to get only a 3db increase in volume. The volume between the w6 and w7 will be very similar given your power. One is 84 db sensitive, the other is 83. You might want to consider going with a ported box as ported boxes require less power. New Project: 2003 Pathfinder

i was thinking more along the lines of bringing it down to 1.5ohms. that would be a very decent increase in power. would this be possible with a resistor?

No.  There is no way to "trick" an amplifier.  It will deliver whatever current it is capable of into whatever load is presented to it.  If you were to add a 3-ohm resister in parallel with the speaker, the amp would deliver whatever it can into the net 1.5 ohm load, but half of it would go to the speaker and half would be burned up as heat by the resister, giving you a net gain of HEAT.  Just conenct your speaker to your amplifier, set your gain properly and go.  If you need "more," get a new amp.Support the12volt.com

First it wouldn't increase power to the sub.  Second, even if it did it would at most double the power output of the amplifer and give you a 3db increase in SPL.  3db is not a lot.  Third, the amplifier would run strained and more distortion would be greater.  Again though, it doesn't work this way - as DYOhn just said, you can't do it.  The quote below should show you why. 

Don't be so hung up with power, you don't need to match rms speaker ratings for the system to be loud and sound good.  If you're into SPL and you want every little db out of the system then, sorry to say, you simply need to buy another amplifier.  If you listen to your music at normal levels, you should be just fine.

See this page:  http://www.bcae1.com/resistrs.htm from http://www.bcae1.com/

 "Using Resistors to Increase an Amplifier's Power Output

As we found earlier on this page, a resistor can be used to dissipate power. Some people believe that they will have an increase in system SPL if they reduce the amplifier load's impedance with resistors. The fact is, the SPL will likely be reduced. Just because the amplifier is producing more power, it does NOT mean the SPL will increase. The reason? The extra power is dissipated in the form of heat and produces no audio. The reason that the SPL will likely drop is because the amplifier's internal power supply will lose some rail voltage with the lower impedance load (the loss may not be significant on amps with highly regulated power supplies). When the rail voltage drops, the output power to the speaker drops. Even if you have an amplifier with a regulated power supply and the power to the speakers doesn't fall, the amplifier will draw more current and run hotter.

In the following diagram, you can see a few different things:

• You can see that the amplifier is producing almost twice the power with the resistor in parallel with the load.
• The rail voltage is reduced with the heavier load.
• The power to the speaker is reduced because less rail voltage is available.
• The current draw has more than doubled. It is more than twice due to inefficiencies within the amplifier.
• The amplifier will run hotter because of more voltage drop across and more current through all of the semiconductors."

New Project: 2003 Pathfinder

thanks for the help guys.  i had thought that would be the case. how far from the 10w7's full potential will i be?

Best thing to do is look at your amp's rating at 2 ohm, and at 4 ohm, and find the difference between the two to give you a pretty close indication of power output into a 3 ohm load.  Looking at the sub manual, it will perform comfortably beginning at about 250 watts, but will not perform to it's full potential until about 500 watts.Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

The w7's will take well beyond 1000 watts of true power, please tell us the amp you want to run this sub on?2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

2007 USACI World Champion

2007 World Record

2006 USACI Finals 2nd Place

i have a jl e1400d. it has 240rms at 4ohms and 400 at 2ohms. both with 12.5 volts. should i be ok?

Well a little underpowered in my opinion, but it will run2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

2007 USACI World Champion

2007 World Record

2006 USACI Finals 2nd Place