Ohms

[Anton]

Ok probably a dumb question, but what is the difference between 2/4 ohms?

Cheers
Anton

[mikeoxford]

ohms is a measurement of resistance.

car speakers are usually 4 ohms, house ones vary (not usually four)

basically a speaker is a big magnet - and a coil.

when the headunit sends power to the speaker it energises the coil, pushing and pulling the cone in and out on the speaker, bit like a electromagnet or summat.

all car headunits - except maybe imported ones, will operate on 4 ohms. this is the amount of resistance the components to your headunit operate at.

so if your 6x9s (or anything for that matter) are four ohms, and so is your headunit, then the 6x9s resist 4 ohms worth of power. fine.

if you put say house speakers (4 ohms ++++)

in your system

they have a higher resistance, and the headunit has to work harder to push the electrical current through. This is why it is stupid to wire house speakers in temporarily!!! thus resulting in a fried headunit (in time)

im guessing if the speakers are lower than 4 e.g 2, the components (speakers) will just go bang if your headunit is on MAX or high for prolonged periods of time

the same effect is when you wire two speakers to one wire on the headunit. put two speakers in the wire and itll double the resistance, unless wired correctly.

this is why tweeters and other components using a crossover are sometimes lower ohm rating. so when they are all wired to the same output, they dont overload the system.

this is how ive always understood it anyway

8) how am i doin cambridge?!

[mikeoxford]

:twisted: other than that m8 the difrence between 2 and four is 2 in my book :twisted:

[Anton]

agh cheers matey, I think I understand now :D

[neiloakley]

voltage = current x resistance

Cars run on 12v (for arguments sake) so at 12v, if you have a 4ohm speaker the max current it can draw is 3 amps.

If you connect two speakers in paralell (+ve1 to +ve2, -ve1 to -ve2) then you will actually HALVE the resistance because the current now has two possible paths to take. A bit like building a bypass round a town.

If you connect two speakers in series (-ve1 to +ve1 to -ve2 to +2) then you will DOUBLE the resistance. A bit like makeing the road thru town twice as long so it is twice has hard to get thru.

So, speakers in series will reduce the current taken from your head unit and consequently reduce the volume.

speakers in paralell will increase the current taken from your head unit causing it to explode in a ball of hairy flames. :twisted:

That is why amps are mostly now 2ohm stable or 1 ohm stable meaning you can put two subs off one channel (4 subs in the case of 1 ohm stable) without any loss of volume. The amp will however get very hot and it will reduce its life.

Hope this helps. If anyone wants any more info, let me know.