Gotta question about ohm ratings

[capitolj80]

Is it common for subwoofer VC's rated at 2 or 4 ohms to actually have a similar but somewhat different resistance in reality? I was checking out the manual of a sub that I'm thinkin about givin a run, and although the advertised resistance is 2ohm per VC, the manual states the each VC actually rates at 1.5 ohms (and 3.3ohms for the 4ohm version). Wouldn't 2 of these (1.5ohm DVC) provide a final 1.5ohm load? My amp puts out more power at 2ohms than 1 (and I wanna maintain as much fidelity as possible), so should I think twice about tryin these subs or is this a common thing and not really gonna make a difference? Thnx for any input

[ttocs]

the rated value of the speaker and what the meter will tell you will almost never be the same.

[Mr. Wild]

DC resistance is a constant 1,5 ohms or 3,3 ohms or whatever. This is what your ohm meter reads out.
On top of that you have speaker reactance, which varies with frequency. Add these up with complex mathematics and voila, IMPEDANCE!

Nominal impedance of car speakers is usually 4ohms or 2ohms, but the ACTUAL impedance varies with frequency .

DC resistance is the absolute minimum impedance a speaker can pose on an amplifier.

Example: JBL 1200GTI subwoofer.

Nominal impedance: Z=4ohms
DC resistance: Re=2,5ohms
Actual minimum impedance in recommended bass reflex enclosure: Z=3,1ohms at enclosure tuning frequency
Actual maximum impedance peaks: Z=15ohms at 21Hz and Z=19ohms at 56Hz

Then there's impedance phase, but I won't go into that..

[dwnrodeo]

Now that is an explanation! With pics too!

[capitolj80]

Ok, that's right, I forgot that resistance varies depending on frequency and other factors. So the rated ohm load is really just an average and with a MINIMUM load of 1.5 (in this case), this is perfectly normal. Good to know...thnx guys