Resistance ratings

[hon_n_gem]

Hi, can someone explain to me the idea of resistance ratings for amps and subs. Ive currently got a Pioneer GMX 762 760W amp. Its two channel and im not sure what the resistance is. I thinks its 2 Ohm when bridged.

Does this mean i have to look for a sub that is 2 Ohm stable? What if i buy a sub that is 4 Ohm stable? Thats what i dont really understand. Also if the sub has a dual voice coil, does this affect anything?? Any help on this is much appreciated!! Thanks.

Hon

 

[RB_172]

Generally speaking, subs are 4ohms - single or dual voice coil.

You cant doing anything with the resistance on a single voice coil one, but with a dual, you can make it 2ohms or 8ohms.

Most amps when bridged will only run double of what they are stable at for 1 channel.

So for me, my 4ch amp can run 2ohms per channel ok meaning when bridged it will do 4 ohms and no less. Now if you have a single voice coil sub, thats not a problem because the two will be matched. With a dual voice coil sub however, youll have to run it at 8ohms (like I am currently) or risk killing the amp!

If you want to run it at 2ohms, go for a mono amp. These can go as low as 0.5ohms I believe!

Hope that makes sense

 

[hon_n_gem]

Thanks for the reply, just one more quick question.

Im goin to get a subwoofer that is a dual voice 2 OHm sub. My amplifier is 2 channel 2 Ohm stable. Does this mean it is a perfect match?? The sub can be run at 4 ohms, and the amp can be run at 4 ohms bridged. Am i correct?? Thanks again

 

[RB_172]

That sounds ok to me.

Might I ask which sub youre going for because ive not seen many (any?) subs with 2ohm coils.

Mind you, Ive not really looked!

 

[Sipha]

Dual 2 Ohm sub can be run

- 1 Ohm parrallel

- 4 Ohm Series.

so its fine, but id get a new amp and run it parrallel cos itll suck more power from u amp i.e ull get the full rating, 600wrms or whatever. (as long as its 1Ohm stable)

 

[hon_n_gem]

yeah i opted for a Rockford Fosgate 2112. Its a 12" Dual 2 Ohm. My dad has 2x 10" and they sound nice. This one is a bit meatier than my old Alpine Type-R, but for some reason it has blown. I havent turned the gain up that high, but apparantly its because i changed HU and because the new one has 4V preouts, i didnt adjust the gain on the amp accordingly :-(

If you were given the choice of a Fosgate 2112 or Alpine Type-R, which would u guys opt for??

 

[Colin_S]

Most amps with the exception on JL and a couple more run at different power at different ohms. If you put a 4 ohm sub onto an amp it will ran at 500watts for example, if you give the amp a 2 ohm load then the amp will run at 750watts. and so on.

Subs are not classed as being x ohm stable that is the way the amps are rated. Subs are just like a resistor and have a set resistance. Subs can be combined and wired in parallel or series to give different loads to the amp.

Amps are classed as being x ohms stable which and this value tells you what load it can handle without blowing up!!! A 1 ohm stable amp can have four x 4 ohm subs wired in parallel which will give a 1 ohm load and this will draw the maximum power from the amp.

 

[hon_n_gem]

Thats a beautiful definition, thanks Colin!!

So when u have dual voice coil, i presume its like playing around with 2 resistors...and using the combination as a load to the amp!

 

[Colin_S]

Spot on Gengar!!!

 

[cuptastic]

ahh ohms law

 

[Colin_S]

Mr. Georg Ohm was a clever man

 

[hon_n_gem]

i do electronics in uni...laugh at me now!!

 

[Colin_S]

I thought you would have been able to work that out then. lol