Resistance of combination wiring scheme?

[Diabolic 10+ year member]

In a three subwoofer system, how is the impedance calculated when wiring two subs in parallel and the third sub in series?

I know there must be a calculator or forumla out there somewhere for "hybrid" wiring schemes like this but I haven't found one, so I thought I would ask here.

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[Diabolic 10+ year member]

More importantly, does this scheme "dilute" the power to two of the speakers, giving an unequal distribution? (I suspect it does but I wanted to make sure).

 

[Gauntlet 5,000+ posts]

Not a good idea....

edit: i wasnt even thinking....are they SVC, and you're wiring 2 subs together in parallel, and then series to the third sub? Or are they DVC?

 

[Matador 10+ year member]

it would give an equal distribution to all 3 of htem

the only problem u would run into is that depending on the impedances of hte sub, u might not be able ot wire them to 2ohms, 4 ohms, or 1 ohms. so it wil be in between.

thus if the amp is rated 1000rms@1ohm, and 700@2ohms, n u wire all the subs to 1.5 ohms, then u 'll only be sending like 850rms to all three.

 

[maylar 10+ year member]

It depends on the impedances involved. Example -

Two 4 ohm speakers in parallel = 2 ohms.

Those 2 in series with another 2 ohm speaker = 4 ohms total.

The 2 in parallel will each get 1/4 the power, and the one in series would get the rest.

Yes, there are formulas to figure all this out but it's beyond the scope of what I can post here. Maybe someone will post a link to an electronics site that explains them.

 

[Diabolic 10+ year member]

Ok, one thing I have learned - which I see has been posted here - is that wiring different resistance combinations will NOT distribute power evenly to the speakers. An example using light bulbs wired to a power source in precisely the same way as I was thinking of wiring my subs shows that one bulb is very bright while the other two are dim. Clearly, this is why such wiring configurations are not given on manufacturer websites, and other sites such as Crutchfield, etc.

The reason I brought this subject up was because I previously had two subwoofers powered by a JBL bp1200.1 @ 1 ohm with a third, dead sub in the same enclosure, acting as a makeshift passive radiator. The performance from this setup (Orions) was outstanding. When I added a replacement sub for the one that was fried, I was forced to rewire the three into a 2.67 ohm load, reducing the power from the amp. Although I was now running an extra subwoofer, the sound level dropped approximately 5db!

I’m a bit frustrated because I know I can get much more out of the three subwoofers, but I would like to do so without having to mount yet another amp! I have several other amplifiers laying around which would be well-suited for the subwoofer but it would be the fourth in the car, with a total draw of almost 300A – well over the capacity of my 211A alternator.

Any tips or suggestions on how to optimize this? The subs are 4-ohm DVC (I can’t believe I forgot to mention that before!).

 

[DaBaller504 10+ year member]

The only way I can think of is to wire them series parallel. Wire subs series, then parallel to amp. Three 8 ohm impedences/three subs. That gives you a 2.67 ohm load. That's all I can think of now. I think thats what you did before. I would maybe say use another amp. Or maybe grab another sub. With another sub you could get a 4 ohm load. But you would still lose power. I say use another amp. But then your alt. Maybe use 2 alts. Just an idea.