4ohm amp 8 ohm speaker?

Question

i am buying an 8 ohm subwoofer because my home theaters speaker output is only 8 ohms and if i get anything higher or lower than 8 ohms it wont work well so i am also planning on getting an amp for it too because without it the subwoofer would only make like barely any vibrations so i am looking over some and i cant decide whether i should buy one specifically for your home or one for your car, the ones for your car are way more powerfull and cheaper but the ones for the house have way less wattage and cost like too much, so i found a few car amps but the only problem is they only support 2ohms and 4ohms, will it still work if i use the 8 ohm speaker? or if i get two 4 ohms and that will add up to the 8 ohm home theater output?

Answer 1

I'm not certain what you’re asking, so I'll try to answer your question the best I can.

1) If you’re buying a sub for your HT, it is advisable to use the rated impedance recommended.  Using a 4 Ohm woofer may be too much of a load for your system, causing your amp to fail.  So yes, putting two 4 Ohm woofers in series (Amp+)--(+woof-)----(+woof-)--(-Amp) could be an option.

2) High power speakers does not always equate to louder ones.  It just means they can handle the rated amount of power without blowing out.  Look at the sensitivity as well.  An 87dB/Watt speaker will require twice as much power to produce the same sound level as a 90dB/Watt speaker.

3) An automotive power amp used in an HT system will require a 12 Volt source to operate.  That is not cost effective option.

Check out Parts Express http://partsexpress.com for some ideas if you want to build something on your own.  They sell kits and pre-assembled speakers too!

Answer 2

If you use a car amp[, you can use an 8 ogm sub. It's just the power would be cut in half if it's expecting 4 ohm. to get around this is to buy an amp that's twice the power for a 4 ohm load. this way it will match the power at 8 ohms.

Oh, and have you thought about how you're going to power the car amp?

A 13.8 volt DC 25 ampere benchtop supply will push 350 watts RMS total at the cost of about $100.