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Old 03-15-2004, 08:52 PM   #11
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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 )

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Old 03-15-2004, 09:15 PM   #12
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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.
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Old 03-15-2004, 09:23 PM   #13
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Quote:
Originally Posted by enmityst
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
Hahahahaha edumacation never hurt anyone
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Old 03-15-2004, 10:06 PM   #14
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Quote:
Originally Posted by Haywood
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.
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>

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Old 03-15-2004, 10:24 PM   #15
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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.
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Old 03-15-2004, 10:33 PM   #16
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Quote:
Originally Posted by Haywood
Just get the 4 ohm sub.
Hear hear! Enough of my foolishness!

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Old 03-15-2004, 11:32 PM   #17
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Cool, thanks!
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