M4tt
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Registered: 18th Apr 03
Location: Potters Bar
User status: Offline
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i was looking at some rocky fossy subs and they say they have an impedence of 2x 4ohms or 2x 2ohms.
what does that mean? what kind of amp do you need, 2 amps or sumin?
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Richie
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Registered: 3rd Dec 02
Location: Newport, Wales
User status: Offline
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ARRRGH  hehe!
2x4 ohms or 2x 2ohms mean they have dual voice coils. If it has two 4 ohm coils, then you can wire these in parallel to give you a 2ohm load, and with a 2 ohm stable amp, will give you a much higher output than you would have had at 4 ohms.
If it has two 2 ohm voice coils, you can wire these in parallel to give you a 1 ohm load, which will once again give you a higher output from your amplifier if it is 1 ohm stable. Alternativly you can wire the two 2 ohm voice coils in series to give you 4 ohms, but that would be pointless really 
to give you an idea of an amps ratings, ill demonstrate the vibe VP4.
at 4 ohms = 450WRMS
at 2 ohms = 750WRMS
at 1 ohm = 1200RMS
hope that makes it clearer not worse for you 
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Richie
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Registered: 3rd Dec 02
Location: Newport, Wales
User status: Offline
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or, if you cant afford an amp that matches the power rating of the speaker when wired in parallell, you can use 2 amps.
Say the speaker is 1000RMS for example, and has two 4 ohm voice coils. You cant afford an amplifier that gives out 1000RMS at 2 ohms, but you can afford 2 amps that give 500 RMS at 4 ohms each (this is just a scenario ppl so dont slaughter me ), then you could wire two amps to the same speaker. You would connect each amp to one of the voice coils.
Can be the same again for the two 2 ohm coils. Say the speaker is 1200RMS. Once again you cant find or afford (scenario again) an amplifier that gives out this power at 1 ohm, but you can get two amps that deliver 600RMS each at 2 ohms, you get what im saying???
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M4tt
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Registered: 18th Apr 03
Location: Potters Bar
User status: Offline
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ah cheers m8, i get it now.
you know some head units have a RCA dedicated to the sub, how would you go about wiring two amps for the sub into this?
would you just split the rca output, or daisy chain the amps (if thats possible)?
tA
[Edited on 11-05-2003 by M4tt]
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Richie
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Registered: 3rd Dec 02
Location: Newport, Wales
User status: Offline
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you can daisy chain the 2 amps, as long as they have a thru put or line out on one of the amps.
If not you can use RCA splitters. Usually the head units that have a sub out just give you the power to adjust the level and frequencies of the sub from the headunit.
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