It'* just a matter of impedance matching. Your amp sounds like it'* designed with a 4 ohm output impedance, so the maximum amount of power will be delivered to the sub if and only if the sub'* impedance is also 4 ohms. With any load but 4 ohms, the power delivered will be less.

(I'll spare everyone the math -- the last time I busted out some theory I killed the thread )

-b

Good call. If the amp isn't designed for lower impedance, it will deliver more power, just for a short time until the protection circuits catch it, or worse yet, smoky time.

Hahahahaha edumacation never hurt anyone

Actually, it'll deliver *less* power -- but more current. Kinda counter-intuitive. But yeah, if the impedance is too low, fuses start blowing.

<geek>

For anyone who'* interested, I plotted the voltage, current, and power response of an amplifier with a 4 ohm output impedance vs. varying speaker impedance (boredom and procrastination can do strange things to a person). You can see it here:

http://www.missouri.edu/~bcc5zb/maxpower.gif

You'll notice that the maximum current occurs when the speaker impedance is zero (when the terminals are shorted -- duh). This'll blow fuses. The maximum voltage occurs when the speaker impedance is infinite (on this graph, 20 ohms = infinity ) The maximum *power*, which is what we're after, occurs somewhere in the middle -- where the load impedance equals the amp'* output impedance -- in this case, at a speaker impedance of 4 ohms.

</geek>

-b

Well... The amp will spill it'* guts out to maintain voltage, the current would usually double with half the resistance (ohms law?) Where'd this start? Just get the 4 ohm sub.

Hear hear! Enough of my foolishness!

-b

Cool, thanks!