Ok so i have 3 12"s in a parellel series. When i hook up my tester to the speaker connection on the outside of the box it says 4 ohms (There is only one connection).. When i hook my amp up will it run in 4 ohms or less??. The futureshop guy said that the amp will run in 2.5 ohms or something like that. BTW the amp ill be using will be a Panasonic GM-D510M.
Thanks guys
Well if yur multi-meter says its 4 ohms then the amp will run at 4 ohms. Its impossible for it to majicly jump down to 2.5ohms. I would go to a new shop. That guy is a idiot.
what he said four ohms is four ohms is four ohms. thats like saying your cav will run 12s once you hook up the battery. it just wont happen.
series you add the ohm ratingv(2+2=4), prallel cuts it in half (2+2=1)
It sounds like he was saying it was CAPABLE of output as low as 2.5ohms, though I doubt it. It's usually 1,2,4,6,8, etc... not 2.5 (though it's possible, it's rare)
yeah 2 and a half ohms seems a little weired.
the amp will run at 4 ohms as long as it is capable of running 4 ohms. the closer you come to matching the impedence of the speaker to what the amp can handle, the less power will be wasted (the output will be more effecient).
another thing. if you stick your multimeter on it and measure 4 ohms, thats fine and all, but thats resistance. your sub does not have a resistance it has an impedence, which is still measured in ohms, but is a little different. impedence involves more than just voltage and current, it involves XC and XL curves.
Injection is nice but id rather be BLOWN!
^ right on the money ^
when you put an ohm meter on the speaker terminal, push on one of the subs and you will see the impedance change, this does really have anything to do with this post so im gonna leave now....
Thanks guys, i actually went with a Kicker KX250.2, Although my previous orion amp had more SQ my new amp pounds!!. I got out of my car around 3pm and my head is still pounding!
i still dont see where this has anything to do with ohms law.
-----------------------------------------------------------------------
-----------------------------------------------------------------------
- Sold my beloved J in April 2010 -
lol idno either, its more to do with amps impedance capabilities... and about the "cutting in half" statement...not true...its like...average impedance divides by the number of loads... like if you have 4 4 ohm loads wired in parrallel it'll be 1 ohm or if you have 2 4 ohm loads in parallel it'll be 2 ohms or 8 4 ohm loads in parallel it'll be .5
wysiwyg wrote:i would say they bang, they don't really pound so much. but if
you want to bump, then they will bump and hit real hard and a lot good. 
LOL
the formulae for the subwoofer impedance is as follows (provided I remember correctly for parallel)
R = Impedance (TR = Total Impediance)
# = Sub or voice coil number
Series
R1 + R2 + R3...... = TR
ex: 4 Ohm + 4 Ohm + 6 Ohm = 14 Ohms
Parallel
(R1 x R2) / (R1 + R2) = TR
ex: (4 x 4) / (4 + 4) = 16 / 8 = 2 Ohms
So... The guy a futureshop is wrong if he told you 3 4 Ohm subs are 2.5Ohms total. It'd be closer to about 1.3Ohms (or 1.5, pretty sure it's 1.3 tho). Obviously parallel is going to lower impedance, and seeing as 2 4 ohm subs is 2 ohms... where'd that extra .5 ohms come from?
That was an interesting bit about the impedance and resistance difference. I never knew that, thx
FIREHAZZRD wrote:^ right on the money ^
when you put an ohm meter on the speaker terminal, push on one of the subs and you will see the impedance change, this does really have anything to do with this post so im gonna leave now....
The changing reading on the meter isn't due to changing impedance, it's because when you move the coil you're generating a voltage which interferes with the meter reading.
