I inherited a brand new Rockford Fosgate stage 2 10" subwoofer (single voice coil) and a sealed box. The problem is the darn thing is 8 ohms.

I went to Best Buy to see if I could buy an mono amp for it and the guy said no amp will work with this sub, sucks to be you.

So any ideas what on earth this sub is for or what I could do with it? I have a feeling it is for using 2 subs wired together or something?
I would love to put it in my car, but Im not sure that is possible.

Any help would be appreciated!

I think you can use any 4ohm amp, the sub will just use about half the power. So if you get an amp that will put out 600w x1 @4ohms, the sub would see about 300w.

Im pretty sure this is right but wait for some one with more audio experience to reply.

Find something that puts out 300+w into 4 ohm mono. Probably like a 75x2 or 100x2 bridgeable amp. It will put out at least half the 4 ohm output into 8 ohm. It's only 3db loss at worst, not as bad as you'd think. Unfortunately not much is built to run a single 8 ohm load optimally.

Alternately, you could buy a smaller amp than you would, 50x2 or 75x2, and a 4 ohm sub. The smaller amp might be cheaper and save you enough money to get a sub. You can also sell the 8 ohm one. Though without a second 8 ohm sub it wouldn't be worth much to anyone else, either.

How in the heck did you inherit just one 8 ohm sub, anyway? Where is its brother?

I think you can use any 4ohm amp, the sub will just use about half the power. So if you get an amp that will put out 600w x1 @4ohms, the sub would see about 300w.

Im pretty sure this is right but wait for some one with more audio experience to reply.

Exactly right. That BB salesman is apparently very new or very dumb. Yes it would be better to have 2 of the subs to create a 4 ohm load, but your sub will still work on any amp. It will receive about half of the rated 4 ohm power. You are better off looking for a 2 channel amp that makes more power at 4 ohms bridged. Most mono amps are designed for higher power into 2 or 1 ohm loads. Unless you look for a regulated amp, like a JL Slash or Phoenix Gold Xenon series. I have a Xenon x200.2 that does over 400 watts bridged at anywhere from 2-8 ohms. It's actually for sale, if your interested shoot me a PM.

yeah a sub with such a high impedance is most likely designed to be used wired in parallel with other subs. 4 , 8ohm subs wired in parrallel = 2ohms .

what kinda amp are you running? I suggest buying another sub to get you down to at least 4 ohms...

BTW don't listen to anything a BB or circuitcity salesman has to say...
I always just kinda smile and nod my head when they are trying to "educate" me :p Then I explane to them how they are wrong :lol:

You could always buy a 4ohm 300-500w resistor and place it inline and make it a 4 ohm sub... not the best solution, but it IS doable...

or, buy another stage 2 sub..

You could always buy a 4ohm 300-500w resistor and place it inline and make it a 4 ohm sub... not the best solution, but it IS doable...

That would get more power out of the amp, but it would all go to the resistor and be converted into heat (A lot of heat, not the safest thing for in a car). It wouldn't get any more power to the sub, and a resistor that can safely handle 300-500w is going to cost more than another sub is.

You could always buy a 4ohm 300-500w resistor and place it inline and make it a 4 ohm sub... not the best solution, but it IS doable...

or, buy another stage 2 sub..

http://www.the12volt.com/installbay/forum_posts.asp?TID=91392&KW=resistor

I wouldn't be too keen on the resistor idea.

Reality sucks, but you are just best to either accept that you are going to lose some power, or get a different sub.

You could always buy a 4ohm 300-500w resistor and place it inline and make it a 4 ohm sub... not the best solution, but it IS doable...

or, buy another stage 2 sub..

I think you meant an 8 ohm resistor in parellel with the 8 ohm sub to get a 4 ohm total load.
And this would accomplish what?

Lets say you have an amp that does 300 watts at 4 ohms or 150 watts at 8 ohms.
If he hooks up the 8 ohm sub to the amp, the sub will receive 150 watts.
If he hooks up the 8 ohm sub and 8 ohm resistor to the amp the sub will still receive 150 watts, and the resistor will get 150 watts which it will give off as heat.

Looks like I just repeated what 2 others said before me. Guess that is what happens when you stop typing for 15 minutes to take a phone call.

You could always buy a 4ohm 300-500w resistor and place it inline and make it a 4 ohm sub... not the best solution, but it IS doable...

or, buy another stage 2 sub..

Regardless, the speaker itself will only accept 8ohms, so you will not get more power to the speaker, but you will make the amp work twice as hard, because it WILL see 4 ohms

Looks like I just repeated what 2 others said before me. Guess that is what happens when you stop typing for 15 minutes to take a phone call.

Crap I did it too. You guys are too damn quick!

or buy a jl amp ( or one that has the same technolgy) that the output stays the same no matter the ohm load placed on the amp. http://mobile.jlaudio.com/products_amps_pages.php?page_id=46

As i said, not the BEST solution....

or buy a jl amp ( or one that has the same technolgy) that the output stays the same no matter the ohm load placed on the amp. http://mobile.jlaudio.com/products_amps_pages.php?page_id=46

I love mis-information

"The "Intelligent" portion of the R.I.P.S. System is a circuit that actually monitors output current to optimize the amplifier's output power over a wide range of load impedances (1.5 ohm to 4 ohm per channel)."

I love mis-information

"The "Intelligent" portion of the R.I.P.S. System is a circuit that actually monitors output current to optimize the amplifier's output power over a wide range of load impedances (1.5 ohm to 4 ohm per channel)."


You can love me some other time:banana: .. .. i stand corrected.. i mis understood what function this did for the amp. Good catch 02silvawagon

As i said, not a solution at all....

Fixed that for you. :D

I love it in BB when people walk up and turn on the DUALS, turn them all the way up and bottom them out, then turn to thier friend and tell them how good they sound :lol:

Thanks for the replies everyone, It was worth a shot anyway.

I guess I'll put it on ebay or something.

Don't forget, an 8 ohm sub is more efficient than a 4 ohm sub so it takes less power to get it to the same output as its 4 ohm sibling.

I have run a single 8 ohm sub and the loss in output is minimal. You can also be sure that your amp will never overheat.

or buy a jl amp ( or one that has the same technolgy) that the output stays the same no matter the ohm load placed on the amp. http://mobile.jlaudio.com/products_amps_pages.php?page_id=46

Thanks for the replies everyone, It was worth a shot anyway.

I guess I'll put it on ebay or something.

I think the smarter thing to do would be to try it out first. You might find you're perfectly happy with it.

Thanks for the replies everyone, It was worth a shot anyway.

I guess I'll put it on ebay or something.

Just because the sub is 8 ohms doesn't mean you can't use it. Just get an amp for it and try it out. It may be enough bass for you. If not, then upgrade the sub later when you get some more money.

Don't forget, an 8 ohm sub is more efficient than a 4 ohm sub so it takes less power to get it to the same output as its 4 ohm sibling.

I have run a single 8 ohm sub and the loss in output is minimal. You can also be sure that your amp will never overheat.

in reality .....he's preaching nothing but truth

why do you think home audio runs nothing but 8ohm speakers???

just run the thing...

ok after last 4 posts and a few beers, I have decided to stop whining and just get some random amp and try it out. I can always upgrade the woofer to 4 ohm wal mart special if it sucks. Thanks for the motivation :banana: ftw

ok after last 4 posts and a few beers, I have decided to stop whining and just get some random amp and try it out. I can always upgrade the woofer to 4 ohm wal mart special if it sucks. Thanks for the motivation :banana: ftw

You could put 5 watts to it and still beat out any Walmart sub :lol:

ok after last 4 posts and a few beers, I have decided to stop whining and just get some random amp and try it out. I can always upgrade the woofer to 4 ohm wal mart special if it sucks. Thanks for the motivation :banana: ftw

That's the right idea. You'll never know until you try it, and my guess is you'll be impressed, or at least surprised at what it could do. One more thing, most single 8ohm subs (for cars at least), are not rated for a lot of power, so even a pretty small 2-channel amp should be fine. The difference between 8ohms and 4ohms will be no more than 3 db, so you should be fun. Have fun!

in reality .....he's preaching nothing but truth

why do you think home audio runs nothing but 8ohm speakers???

just run the thing...


they run 8 ohm speakers because, most, home audio amplifiers are 8 ohm and are not designed to with stand a 4ohm load... now there are some that can but in general most are 8 ohm for that reason.

Same thing with most coaxials that you find for car audio...they most of the time will be 4 ohm...why? because your typical head unit is 4 ohm.:devil:

they run 8 ohm speakers because, most, home audio amplifiers are 8 ohm and are not designed to with stand a 4ohm load... now there are some that can but in general most are 8 ohm for that reason.

Same thing with most coaxials that you find for car audio...they most of the time will be 4 ohm...why? because your typical head unit is 4 ohm.:devil:

Which came first, the speakers or the amps? The chicken or the egg? Your logic is flawed.

There are plenty of 4 ohm stable home audio amps and plenty of 4 ohm home speakers as well. Just not the cheap crap you can buy at Best Buy or CC.