Discussion in 'Amps and Cabs [BG]' started by Quadzilla, Mar 4, 2002.

Please excuse my ignorance but if a head says (4 ohm minimum) under the 2 output jacks I assume that means that you can run these configurations:

1 - 4 ohm cab
1 - 8 ohm cab
2 - 8 ohm cabs (one from each jack)

I also assume that you CANNOT run the following:
2 - 4 ohm cabs
2 - cabs one at 4 ohm and one at 8 ohm

Am I right on this?

Thanks

2. Johnny BoomBoom

Jun 8, 2001
Glasgow, Scotland
The formula for working out resistance in parallel is:-

1/Rt = 1/R1 +1/R2 ........

This can go on however for your examples:-

1. 1/Rt = 1/R1 therefore

1/Rt = 1/4 therefore

Rt = 4 ohms (Rt is the total resistance)

-------------------------------------------------

2. 1/Rt = 1/R1 therefore

1/Rt = 1/8 therefore

Rt = 8 ohms (Rt is the total resistance)

-------------------------------------------------

3. 1/Rt = 1/R1 + 1/R2 therefore

1/Rt = 1/8 + 1/8 therefore

1/Rt = 2/8 = 1/4 therefore

Rt = 4 ohms (Rt is the total resistance)

I run my two 8 ohms cabs daisy chained into each other - ie head to cab1, cab1 into cab2. This resul;ts in a 4 ohm load as they are in parallel

------------------------------------------------

1. 1/Rt = 1/R1 + 1/R2 therefore

1/Rt = 1/4 + 1/4 therefore

1/Rt = 2/4 = 1/2 therefore

Rt = 2 ohms (Rt is the total resistance)

------------------------------------------------

2. 1/Rt = 1/R1 + 1/R2 therefore

1/Rt = 1/4 + 1/8 therefore

1/Rt = 1/8 + 2/8 = 3/8 therefore

Rt = 2.67 ohms (Rt is the total resistance)

Hope this helps!!

Edit - to prevent confusion (I hope)

3. Bass_Pounder

Jan 19, 2002
Palm Coast, Florida
Let me simplify Johnny Boom's post:

YOU CAN:

1 - 4 ohm cab (total 4 ohm load)
1 - 8 ohm cab (total 8 ohm load)
2 - 8 ohm cabs (total 4 ohm load)

YOU CANNOT:

2 - 4 ohm cabs (total 2 ohm load)
1 - 4 ohm cab + 1 - 8 ohm cab (total 2.67 ohm load)