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      06-05-2006, 09:43 AM   #1
longhorn35
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2 ohm vs 4 ohm

Do the HIFI and Logic Seven have 4 Ohm subs under the seats? I am reading the spces and it looks like they are 2 ohm?

Forgive my lack of understanding of Ohm-age but what will happen if I put 4 Ohm speakers on a 2 Ohm connection?
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      06-05-2006, 11:23 AM   #2
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Quote:
Originally Posted by longhorn35
Do the HIFI and Logic Seven have 4 Ohm subs under the seats? I am reading the spces and it looks like they are 2 ohm?

Forgive my lack of understanding of Ohm-age but what will happen if I put 4 Ohm speakers on a 2 Ohm connection?
R = resistance in ohms
V = 12 volts
I = current in amps


Ohms Law:
R = V/I
I = V/R

For 2 ohms
I = 12/2 = 6 amps

For 4 ohms
I = 12/4 = 3 amps

Therefore, if you use 4 ohms, you will not get the max-current (amps) a.k.a umph !

I think this is right, it has been 12 years since I graduated from engineering school.
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      06-05-2006, 11:29 AM   #3
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Quote:
Originally Posted by AskNiko
R = resistance in ohms
V = 12 volts
I = current in amps


Ohms Law:
R = V/I
I = V/R

For 2 ohms
I = 12/2 = 6 amps

For 4 ohms
I = 12/4 = 3 amps

Therefore, if you use 4 ohms, you will not get the max-current (amps) a.k.a umph !

I think this is right, it has been 12 years since I graduated from engineering school.
So to get max current, will I need to get additional wattage from another amp source?
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      06-05-2006, 11:46 AM   #4
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The connection doesn't determine the resistance the speaker does. If you connect a 4 ohm speaker to an amp that's rated at lets say 400 amps @ 2ohms you'll get 200 amps running the speaker given that the voltage is the same. This is why high end amps that can operate reliabily at lower resistances are so desireable. You can wire speakers in parallel, lower the resistance, and effectively get a great deal more amperage to run your speakers. The problem comes when you connect say a 2 ohm load to an amp that only rated to be stable at 4 ohms in which case you could damage the amp. I hope I got all that right and I hope it helps. As far as what resistance the speakers are and how they're wired? I think there was a thread earlier where E90Fleet posted the speaker specs. Try a search. I have no idea on how they're wired though.
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      06-05-2006, 11:48 AM   #5
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Quote:
Originally Posted by longhorn35
So to get max current, will I need to get additional wattage from another amp source?
To optimize, use 2 ohm speakers.

Sounds like the this is already at speaker level so it is not good to amplify at that stage because you will also amplify the noise.

If you want to amplify, get it from signal level, then amplify. Results should be cleaner.

To keep it simple, just use 2 ohm speakers as the specs say.
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      06-05-2006, 11:50 AM   #6
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Quote:
Originally Posted by AskNiko
To optimize, use 2 ohm speakers.

Sounds like the this is already at speaker level so it is not good to amplify at that stage because you will also amplify the noise.

If you want to amplify, get it from signal level, then amplify. Results should be cleaner.

To keep it simple, just use 2 ohm speakers as the specs say.

Where can you find 8" subs that are 2 Ohm?
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      06-05-2006, 02:09 PM   #7
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Quote:
Originally Posted by longhorn35
Where can you find 8" subs that are 2 Ohm?

This post might answer your questions...

http://www.e90post.com/forums/showthread.php?t=19036
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      06-05-2006, 08:53 PM   #8
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The factory HiFi subs are 2 ohm. I just finshed a system that utilizes them. They actually can produce some substatial soun.
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