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Discussion Starter · #1 ·
Most of my speakers are 4 ohms. But I notice that some kit is only 2 ohms. Why?

I gather mixing impedances causes noise and feedback etc. So does it mean I can put 2 x 2 ohm speakers in series and maintain my 4 ohm system?:confused:

And dual coil..... what's that all about?
 

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A 4ohm speaker has twice the resistance to current than a 2ohm speaker does. This means the 2 ohm speaker will allow "more" current to pass to the coil than the 4 ohm speaker, hence the coil resistance. 2 ohms is less than 4 ohms, therefore there is less resistance to the incoming power. Factory amplifiers in HU are either rated 4 ohm or 2 ohm. What does this mean if you have a HU rated at 4 ohms and you install speakers rated at 2 ohms? Eventual death of the HU because the speakers have less resistance to the power coming from the HU therefore the HU will clip, or distort at higher volumes, and more current will flow through the speakers coils that the dampining factor of the HU can compensate for safely. Reverse the equation, 2 ohm HU and 4 speakers. Very unhappy driver because there is MORE resistance to the curreent from the HU, thus less, alot less volume, or music at any level vs. if the speakers matched the HU.
 

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Formerly known as boscombesurfer
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1,315 Posts
Unless you are running amps that are capable of handling different impediances just stick with 4ohm. As above headunits internal amps will not like this at all.

These amps will deliver much higher rms wattage with the different loads shown to them. Back in the 90's these were known as cheater amps and were expensive bits of kit.

These days it is more likely you will see maybe a dual 3ohms sub were a quality amp is installed, normally with a regulated power supply otherwise they run very hot indeed. Any lower and you draw much more power.

What were you thinking of doing?
 
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Discussion Starter · #5 ·
I picked up a stack of ICE from ebay and was going to play. I have 1 x 4 ch Alpine Amp, 1 x mono Alpine sub woofer amp, 1 x JBL 2 ch amp and a pair of Pioneer W306C subs, and intend running a pair of 6x9s, a pair of 6" components and a pair of 10cm dash speakers (probably direct from the head unit). My head unit is fairly crappy (Sony Xploder 4 ch unit with no RCA connector etc), so I was looking for a Kenwood head unit with at least 2 RCA connectors and it must be compatible with a Kenwood 10 CD changer I also have. All to be run from an 85ah utility battery in the rear.

I figure that I'd use the head unit (4ch speaker feeds at the moment) to supply the 4ch amp, the sub amp and the dash speakers, then feed the two 6 inch compos and the 2ch amp (to the 6x9s) from the 4ch unit.
 

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Formerly known as boscombesurfer
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1,315 Posts
Complex speaker set up! Just make sure that any amp asked to deliver more power (lower impedance) can run that. Most modern amps are cheaply built and have regulated power supplies.

If you like ebay there is a phoenix gold ZPA0.5 on there at the moment, that can handle down to even half an ohm! When you look for a new headunit make sure it has a high voltage output.

Keep us updated with pics.

I am running 4volts from an Alpine into a PG ZX450 running Rainbow comps up front and rear fills. Will be fitting dual 3 ohm sub soon if I ever get around to fitting new amp and making enclosures! Think I am already drawing a lot of curent though so may need to rethink power supply up from 4 guage.
 
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Discussion Starter · #8 ·
One more question though. Surely if the external amps are driving the speakers and the HU is only providing a signal to the amps, then the HU should be well within it's tolerances as it is providing only the minimum load?
 

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i am t4lwb steve
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2,832 Posts
yes
but if you run the 4and the 6" off the head unit that will mean you will not over load the speakers by forcing to much wattage thro' them
as for the amps amd the speakers if you have brought car audio stuff it will be all 4 ohm standard with the exception of the subs as they come in single and duel voice coils and then 4-2-1 ohm

but by putting the subs or speakers in series will lower the ohmage =less resistance
which means higher volume but shorter life span if set up on incorrect systems T:
 
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