series/parallel sub wiring

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=106694
Printed Date: September 13, 2025 at 12:34 PM

Topic: series/parallel sub wiring

Posted By: zerogravity3000
Subject: series/parallel sub wiring
Date Posted: August 10, 2008 at 2:27 PM

Does anyone have an equation for calculating a series/parallel ohm load where all the values are equal?

Because... I want to wire eight 4 ohm single voice coil subs to a mono amp that is 1 ohm stable

I could just wire them as two groups of four subs in parallel and then wire the two groups together in series for a total load of 2 ohms, But i would like to get the most out of my amp, since it is one ohm stable.

Further info:

the subs have a power handling of 120 RMS each

the amps output is rated at 760 RMS @ 2 ohm and 1200 RMS @ 1 ohm load

Replies:

Posted By: i am an idiot
Date Posted: August 10, 2008 at 2:33 PM

You have 2 choices, settle for the 2 ohm load. Or buy 8 ohm woofers. .

Posted By: zerogravity3000
Date Posted: August 10, 2008 at 3:18 PM

thanks for the response...

do you mean that there are no possible combinations of series/parallel wiring for eight 4 ohm subs that is both greater than 1 ohm and less than 2 ohms?

someone suggested that if i ran five of the subs in parallel and the remaining three subs in series i would end up with a total load of 1.14 ohms (which would satisfy my power requirements for these subs) but i would like to double check the math myself...

do you (or anyone) have a link to a clear description of the proper equation for this calculation?

Posted By: i am an idiot
Date Posted: August 10, 2008 at 3:37 PM

There is no possible (Useable) combination that will yield more than 1 but less than 2 ohms. (5) 4 ohm speakers paralleled = .8 ohms. (3) 4 ohm speakers run in series = 12 ohms. Those 2 sets ran in series = 12.8 ohms. Those 2 combinations then run in parallel = .75 ohms.

Posted By: haemphyst
Date Posted: August 10, 2008 at 5:51 PM

Not only that, but:

1: The amp will run hotter. (lower efficiency)
2: The distortion will be higher. (maybe inaudible, but still)
3: The damping will be lower. (less control over the bass)
4: There will be LESS THAN 3dB difference in total output. (are you competing, where this will be the difference between winning and being first loser?)

All bad (1, 2, and 3) and/or COMPLETELY un-noticeable (4).

Run the system at 2 ohms, and be happy. If you wire in an unbalanced series/parallel combination, (i.e. 3 in series with 5 in parallel... or whatever hairbrained scheme your friends told you would work... It won't.) you will have unequal output from the woofers. There is no way to acheive 1 ohm with eight 4 ohm woofers. Here's the page... You will run two sets of four woofers, just like this.

Also, check this... (Just in case you were thinking THAT might be a way around it...)

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