i have 3 dvc subs that can be connected at 2ohms or 8ohms.
now... if i connect sub 1 in series to get 4 ohms and sub 2 in series to get 4 ohms and then these same two subs together in series (to get 8ohms), then the third sub at 8 ohms in parallel to subs 1&2, theoretically i should then get a total load of 4ohms, right???

 

The equation you want to use for resistance is a parallel circuit is 1/Resistance of Parallel=1/R1+1/R2+1/R3 and so on. If you add up 1/4 (the third sub) and 1/8 (the two subs in series) you get 3/8, which then you take the reciprocal of. That gives 2.66 ohms.

So you wouldn't get 4 ohms, you'd get 2.66.

If you do two in parallel and one in series you'd get 6 ohms.

But if I undersand you correctly, you each VC of each sub is 4 ohms, so you wouldn't be able to get 4 ohms out of each sub, only 2 or 8.


[Modified by Ein, 9:55 PM 11/11/2001]


[Modified by Ein, 9:58 PM 11/11/2001]

 

THe only way you're getting 4 ohms on those subs is by using six amps each connected to each VC. I do not recommend doing that though.

You can get either 2 or 8 ohms by using two tweeters. They won't be doing anything except adjust the impedance provided that you're using x-overs.

Why wire them at 4 ohms?



[Modified by redblues, 5:37 AM 11/12/2001]

 

I agree with your math BUT the one speaker you are running at 8 ohms is going to handle the same power as the the two speakers in series and that 8 ohm speaker will blow. You are better off using two speakers only. Keep it simple!!

 

redblues - "Why wire them at 4 ohms?"
my amp wants to see 4 ohms when bridged.

Ein - "If you add up 1/4 (the third sub) and 1/8 (the two subs in series) you get 3/8, which then you take the reciprocal of. That gives 2.66 ohms"
true, but my third sub is at 8 ohms not 4.

Teken - i understand how your config would yield 4.66 ohms, but if i could get a configuration with an impedence of 4 ohms, i would rather take that configuration.
Let me reiterate the configuration that I posted originally because it was probably unclear.
R1=4 ohms R2=4 ohms R3=8 ohms.
sub 1 and 2 will be configured in series. This series load will then be placed in parallel with my 8 ohm (3rd) sub.
Rt= 1/8 + 1/8 = 4ohms
theoretically, is this correct?
in practicality, i was told that you shouldn't mix subs with different ohm impedance. is this true?

thanks guys for any help you can give me.