4 ohm vs 8 ohm subs

[Sethro]

I found a good deal on two 10" RF subs, but they are 8 ohms. Can someone explain the differences(pros cons) of 4 ohm vs 8 ohm subs? Thanks

 

[TTG]

I'm no expert on this, but this is what I've gathered about the subject...

The Ohms rating is the resistance the speak will show to the amp. The more resistance shown, the less power that gets there. Most Amps will show their max power ratings at 2 Ohms. However, most speakers and subs are 4 Ohm, or Dual 4 Ohms Coils. You're not supposed to mix Ohms ratings, so you're supposed to have 4 all around or 2 all around or whatever. Also, if you wire 2 subs together out of the same amp, they will add their resistances together. I would think that the subs are just dual 4 Ohm coils, but I may be wrong. If not, they would show a total of 16 Ohms of resistance to your amp which would cause a HUGE amount of power to not reach them. I suppose the 8 Ohms would be a little more efficient.

 

[rome85CT]

no no, the ohm's get added together and divide themselves down as you increase the number of subs your putting together, for example 2 and 2 ohm subs wires down to 1. etc. or you can take the easy way out when your lazy and go to rockfordfosgate.com. they have a wiring wizard on there, all you do is input the numbers and it will tell you what the ohm's are and also how to wire your subs down. as long as the impedance is higher than amp is rated for, youll be A ok.

heres the wiring wizard if anyone is interested. http://www.rockfordfosgate.com/rftech/wiringwizard.asp

 

[leenjen]

the two 8 ohm subs will produce a 4 ohm load when run in parallel. that will wior with just about any car audio amplifier. do not run them in series. it wont hurt anything, but 16 ohms is very inefficient.

if the subs were 4 ohms subs, you would need a 2 ohm mono amp. those amps are usually a little more expensive then the average 4 ohm mono amp. you could run them 4 ohms stereo, but again that is less efficient. it would be the same as wiring them @ 8 ohms mono.