anybody have anything to say about this brand? somebody is selling me a 15 inch of this sub for $200. Is it worth it?

 

Onyx is long gone sad to say....good subs though. Do you know the model number?

 

nop but i will try to find out. They are huge though! how's their worth? According to the owner it can be configured to run as 1, 2, 3, or 4 ohm.

 

whats the impeadance on the coils?

 

Judging on the fact it can only run down to 1 ohm, it MUST be a quad 8 ohm voice coil.
(8/2=4, 4/2=2, 2/2=1)

 

You mean a quad 4ohm, as a quad 8 could never achieve any lower than 2ohm.

But that's IF the guy who told Freshman this was correct, which I highly doubt in the first place since he mentioned it could hit 3ohms, hence my question.

 

naahhhh... quad 4's could hit .5 ohm.
Cant draw a schematic for ya, but here.
4ohm to 4ohm = 2 ohm.
Add in another 4 ohm, you get 1 ohm.
Add in another 4 ohm to the 1 ohm you get .5 ohm.

But i do agree with your second statement.

 

unfortuantely no, allow me show why. A voice coil is both resistive and inductive but for calculating resistance in systems we ignore the inductive effects. A DMM will show this to be true as well.


The formula for determining final resistance when resistors are in series is:
R(f) = R(1) + R(2) + R (3) + R(4) +...+ R(x)

The forumla for determining resistance when resistors are in parallel is:
1/[R(f)] = 1/[R(1)] + 1/[R(2)] + 1/[R(3)] +...+ 1/[R(x)]



Ok so you have 4 4ohm coils
1/R(f) = 1/4 + 1/4 + 1/4 + 1/4
1/R(f) = 1.0
1 = R(f)
thus the lowest impeadance achievable with 4 4ohm coils is 1 ohm.

If you have 4 8 ohm coils
1/R(f) = 1/8 + 1/8 + 1/8 + 1/8
1/R(f) = 1/2
1 = R(f)/2
R(f) = 2
Thus the lowest impeadace achcieve able with 4 8 ohm coils is 2 ohm.



To achieve a 0.5ohm load you'd need eight 4ohm coils...

 

I love the smell of electronic geekiness in the morning.

 

So what happens when you have 3 4 ohm voice coils then?

 

1/R(f) = 1/4 + 1/4 + 1/4
1/R(f) = 3/4
R(f)= 4/3 = 1.333

Then you will have a final impeadance of 1.33ohms.