Cabinet OHM

cvor

New member
Embarrassed to ask given I've owned VH4 well over a decade. Want to confirm understanding of which speaker outs to use. I have a Mesa 2 12" speaker cab that says 8 ohm on it. I've been plugging it into the "1x8" jack. Is that correct?

When I have another Mesa 2x12" 8 ohm in it, I've used both of the "2x8" jacks. Is that correct?

If I use one 2x12" 8 ohm and 2 separate 1 12" cabinets that say 8ohm how would I do that?
 
You've been connecting your Mesa 2x12 correctly into the 1x8 jack, and also correctly when paired with a second 8 ohm cab by using the 2x8 jacks.

Basically, from left to right, the output jacks are 4 ohm, 8 ohm, 16 ohm.

You're not going to be able to run 3 cabinets correctly from a single head. You'd be looking at an ohm mismatch. 8 ohm + 8 ohm = 4 ohm load, and the VH4 (and pretty much all other heads) don't have outputs for lower than 4 ohms.
 
just take speaker cable plug it in to your 1 x12 cab and measure resistance. 8 ohm speaker will show something around 7.9 ohm on tester.
 
Two 8Ohm cabs, use 4 Ohms (left).

1 8Ohm cab, use 8Ohms. (This is also used for two 16 Ohm cabs).

I highlighted both.

The reason is that the Ohm's Law says parallel wiring goes like this:
R : resistance in Ohm
1/R1 + 1/R2= 1/R
e. g. 1/8 + 1/8 = 2/8 = 1/4 => 4 Ohms for two 8 Ohm cab
 

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