# Ohm Rule

Discussion in 'Amps and Cabs [BG]' started by JoeVictim, Dec 12, 2006.

1. ### JoeVictim

Nov 3, 2006
Colorado Springs, CO
checking to make sure I am not brain dead. If I have 2-4 ohm cabs,(2ohms) and 1 8ohm cab, This should make 4 ohms?

2. ### Espidog

May 19, 2006
UK
Not quite - at least not the way you're thinking it out.

To end up with 4 Ohms, you'll need to do this:

1) Connect the two 4 Ohm cabs in series, making 8 Ohms. Think of this pair of cabs as one 8 Ohm unit.

2) Now, run that unit in parallel with the other 8 Ohm cab, and you'll get 4 Ohms.

If you just ran all the cabs in parallel, you'd end up with a disastrously low 1.6 Ohms !

3. ### telebasser

Nov 7, 2006
East Tennessee
+1! Yes, speaking in parallel terms:

(impedance of cab 1 X impedance of cab 2) / (impedance of cab 1 + impedance of cab 2)

For instance, if you have a 2-ohm cab and an 8-ohm cab:
multiply 2 x 8 = 16
then 2 + 8 = 10
16 / 10 = 1.60 ohms which equates to FIRE!

Series means chaining the cabinets together one to the next. Parallel means sending one output of the bass amp head to one cabinet and a second output from the head to another cabinet. Parallel is two (or more) side-by-side connections. Most of the time you will wire bass cabinets in parallel.

Aug 22, 2002
Bellingham