Convert passive subwoofer to active subwoofer

[J Zimm]

I'm trying to connect a sound bar with a sub out port to an amplifier and then to a "home theater box set" subwoofer. The amp I am currently using puts out ~80 Watts across 2 channels. The subwoofer is the real issue since it is 1.5 ohms. The system "works" until the bass gets too heavy and hits the amp's power limit which shuts it off. Tips, tricks , hardware to buy??

 

[americanaudiophile]

If the sub comes from a HTiB you are probably not running out of power. The amp may not stable enough to put out it's rated power into a 1.5 ohm loud. You could try putting a 4 ohm resistor in series with the plus speaker wire. 50 -100 watt power rating
http/www.sears.com/unique-bargains-car-aluminum-4-ohm-50w-5/p-SPM7925991723?hlSellerId=29267&sid=IDx20110310x00001i&kpid=SPM7925991723&kispla=SPM7925991723
http/www.parts-express.com/4-ohm-100w-non-inductive-dummy-load-resistor--019-015
or replace the woofer with one with higher resistance. Parts Express can help there too.

 

[J Zimm]

If the sub comes from a HTiB you are probably not running out of power. The amp may not stable enough to put out it's rated power into a 1.5 ohm loud. You could try putting a 4 ohm resistor in series with the plus speaker wire. 50 -100 watt power rating
http/www.sears.com/unique-bargains-car-aluminum-4-ohm-50w-5/p-SPM7925991723?hlSellerId=29267&sid=IDx20110310x00001i&kpid=SPM7925991723&kispla=SPM7925991723
http/www.parts-express.com/4-ohm-100w-non-inductive-dummy-load-resistor--019-015
or replace the woofer with one with higher resistance. Parts Express can help there too.

I bought some resistors and they worked, what's the science for why that works?