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Old 26th July 2006, 01:27   #1
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Exclamation Subwoofer Impedance

My friend got a pair of Audiobahn ALUM12Ns, they have Dual 6 ohms coils,

Now he also has a 2 Ohm Stable Mono amp,

How do we achieve optimum power ?

If we wire the 2 coils in parallel each sub becomes 3 Ohms,
and both subs are connected in parallel to the amp should be 1.5 Ohms, now what does the amp do cos it is either 2 Ohms stable or 4 Ohms stable, how will the amp work, what are the pros and cons of this setup ?

Experts throw some light
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Old 26th July 2006, 01:58   #2
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Quote:
Originally Posted by 929RON
My friend got a pair of Audiobahn ALUM12Ns, they have Dual 6 ohms coils,

Now he also has a 2 Ohm Stable Mono amp,

How do we achieve optimum power ?

If we wire the 2 coils in parallel each sub becomes 3 Ohms,
and both subs are connected in parallel to the amp should be 1.5 Ohms, now what does the amp do cos it is either 2 Ohms stable or 4 Ohms stable, how will the amp work, what are the pros and cons of this setup ?
You can only do 1.5 / 6 / 24 ohm configurations... What amp does your friend have... Cuz most 2ohm amps will buckle under a 1.5ohm load. Note: I said most.

Ideal solution: tell your friend to get a 1ohm stable amp... Or get another sub...
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Old 26th July 2006, 02:46   #3
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He has a Rockford Fosgate Type RF X7.A 1500 RMS @ 2 Ohms, so this is not safe for the amp is what you saying ?

So will a 1 Ohm Stable RF T10001bd work good with these subs ?
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Old 26th July 2006, 10:28   #4
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Redundant Question.. Gunbir already stated ANY 1 Ohm stable sub WILL do the job! ..

EXPERTS:... Can he not present a 6 ohm load to a two/four ohm stable amp...?? .. or does it necessarily have to be multiples... The fallout of course will be power.. but the amps will aso run cooler wont they?...

Last edited by kb100 : 26th July 2006 at 10:30.
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Old 26th July 2006, 10:49   #5
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Quote:
Originally Posted by kb100
Redundant Question.. Gunbir already stated ANY 1 Ohm stable AMP WILL do the job! ..

EXPERTS:... Can he not present a 6 ohm load to a two/four ohm stable amp...?? .. or does it necessarily have to be multiples... The fallout of course will be power.. but the amps will aso run cooler wont they?...
Yes, he can always run 6ohms on the amp... it will run fine, except they wont get maximum output from their amp.
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Old 26th July 2006, 14:09   #6
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Try 1.5 ohm final load and see if amplifier can take it, set the gains properly. If amplifier is well ventilated and gains are adjusted properly it might run those subs wired in 1.5 ohms final load.

If not go for 6 ohms final load. In which amp sould give you around 600Watts. Which I think is good as ALUM's are quite sensitive.

Ideally as everyone has suggested go for 1 ohm stable amplifier or DVC4 ohms subs.
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Old 26th July 2006, 14:39   #7
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I think the RF amp should be able to just get away with 1.5 ohms, like Autophile correctly pointed out, if provided with proper ventilation and with gains set up below normal.
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Old 27th July 2006, 00:42   #8
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Will test the setup out and will let u guys know what happened, I have used a Type RF X6.A earlier and man that amp has efficient cooling, blasting 1100 RMS with a pair of 600 RMS Dual 4 Ohms L5s wired at 2 Ohms final load, it used to run cool for hours, never heat up or cut out bcos of overheating, I have blasted the subs for 1 hr at a stretch while driving and the amp was just a little warm, have seen some Power series amps by RF itself which used to heat up good enough to cook omlettes.
Now will see how the Type RF fairs with the ALUMs.
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Old 28th July 2006, 14:48   #9
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Quote:
Originally Posted by 929RON
have seen some Power series amps by RF itself which used to heat up good enough to cook omlettes.
Now will see how the Type RF fairs with the ALUMs.
In this case, there's a good chance that you'll be frying eggs on the cone surface of your Audiobahn subwoofer too. The Alums dissipate a lot of voice coil heat from the Aluminium cone. So dont get scared when that happens. There's something wrong if they don't heat up actually!
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Old 28th July 2006, 15:36   #10
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Quote:
Originally Posted by Bass&Trouble
In this case, there's a good chance that you'll be frying eggs on the cone surface of your Audiobahn subwoofer too. The Alums dissipate a lot of voice coil heat from the Aluminium cone. So dont get scared when that happens. There's something wrong if they don't heat up actually!
Do you think the cone will get that hot? I mean 300-400cm2 of heat sink dissapating heat from a voice coil that is anyway ventillated.
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Old 28th July 2006, 22:26   #11
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Quote:
Originally Posted by Bass&Trouble
In this case, there's a good chance that you'll be frying eggs on the cone surface of your Audiobahn subwoofer too. The Alums dissipate a lot of voice coil heat from the Aluminium cone. So dont get scared when that happens. There's something wrong if they don't heat up actually!
Its not mine, its for a friend, will let you know when the testing is done, as of now our man is very busy and the installation is not even done,
But that Rockford sure Churns out a lot of power 1500 RMS in a hatchback is deafening enough !
Cheers
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Old 29th July 2006, 20:05   #12
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Quote:
Originally Posted by navin
Do you think the cone will get that hot? I mean 300-400cm2 of heat sink dissapating heat from a voice coil that is anyway ventillated.
Yessir! Of course not as hot as heat sinks on some searing amplifiers, but very hot for any cone's standards.

True that the voice coil is ventilated, but it is restricted to the air inside the enclosure only, if the enclosure is a sealed one. However since Al conducts well, and really quickly compared to convection to air, a lot of heat is channeled out from the cone. I've seen some Al cone subs with a lot of power input get really really hot. This inspite of the fact that most morons using one-piece Al cones sometimes use a plastic neck to attach the cone to the former.
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