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different ohm setup cause probs?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=26378
Printed Date: July 17, 2025 at 9:16 PM


Topic: different ohm setup cause probs?

Posted By: McFord
Subject: different ohm setup cause probs?
Date Posted: February 12, 2004 at 11:20 PM

i have 2 dual 4 ohm subs i want to hook up....

basically i can wire em at 2 ohms or 8 ohms each

the sub amp i have is a mono and only stable to 2 ohms

if i run one sub at 2 ohms and one at 8 and parallel that it should give me a 1.7 ohm total load on the amp.., BUT will each speaker get teh same ammount of power?...if the amp is puttiing out 500rms will each sub get 250 or will teh 2 ohm one get more??

i could just run the subs at 4 ohms, but i lose a lot of potential power from the amp there and i figure 1.7 is close enough to 2 since ohms arent really static number in the real world.

i'm going to get a 1ohm stable amp (jbl 1200.1) and use it, but till then i have to make do with teh mono block i have....so how should i wire it?




Replies:

Posted By: thapimpfromchi
Date Posted: February 13, 2004 at 12:09 AM
hmm... in a situation like that, im not too sure. I just had a long discussion with this with a guy on here. Im not sure how that would work, but, if the amp is only 2 ohm stable, i wouldnt go lower. why run the risk of damaging you equipment? i'd say run it at 4 ohms. when you get the JBL, it'll just make it that much sweeter. posted_image

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1990 Honda Civic HB:
Clarion DXZ545MP H.U.
2- 6.5" Power Acoustik interiors
Diamond Audio 600.1 amp
Diamond Audio 15" M6MKII
Pyramid PB881X 4 CH. Amp




Posted By: aggie altima
Date Posted: February 13, 2004 at 6:13 AM
The two subs will each get different power. The power is ONLY split evenly between subs when they all have the same resistance. Just trying to explain this through what I know.
If you had 2 different resistors in series, and you put a voltage across the two, the voltage across each resistor would be different (using voltage division), which would equate to the speakers getting different amounts of power. If 2 resistors are in parallel, the voltage across each resistor would be the same, but the current would be different according to ohm's law (current division). This difference in current would also equate to a difference in power to each sub.
The actual load the amp will see is 1.6 ohms. The equation for two resistors in parallel is (r1*r2)/(r1+r2), where r1 and r2 are the resistance of each sub. This equation is only for two subs, whereas the equation for three subs would be completely different.
If this confused you, sorry. The main point is that the subs wouldn't be getting the same power, so they won't be playing at the same loudness or volume. Your best bet would be to just wire them to a final load of 4 ohms.




Posted By: forbidden
Date Posted: February 13, 2004 at 2:19 PM

Your best and safest bet is to wire these subs in a series / parallel combination and let the amp see a 4 ohm mono load. There is no way with the subs that you have to let the amp see a 2 ohm load. Different subs or a different amp would be the best bet.



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Top Secret, I can tell you but then my wife will kill me.




Posted By: McFord
Date Posted: February 13, 2004 at 5:08 PM

yeah..after thinking about it in terms of resistance, it cant work....i mean as far as the load presented to the amp it COULD work, but it would not be good for the subs...so 4 ohms it is for a few weeks......thanks






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