My backup MB200 4 ohm question.
 

I just purchased a GK MB200 as an emergency backup. I use presently an Ampeg PF500 with 2- PF115HE Stack. Can I use the MB200 on one PF115HE cab which is 8 ohms or do I have to use the Mb200 on both cabs which are 4 ohms. Not very savy with the ohms stuff. This is a senario only if my PF500 craps out at a gig. :help:

I have an MB200 and have run it into two 8-ohm Genz Benz Focus 115's. I usually just use one though

You don't "have" to use it with both, but why wouldn't you? The amp will take the 4 ohm load and more speakers move more air.

I wasn't sure how a 4 ohm amp works with one 8 ohm cab. Does it reduce the wattage or does a 4 ohm amp need to be connected to a 4 ohm cab in order to get its full wattage?

All this is covered in the owners manual.
free download at the GK site BTW.

Maybe someone will have a quick answer for my quick question.

Well, yes and yes. With a solid state amp (versus a tube power section, which behaves differently), the amp will deliver more power to the speaker(s) as the nomimal impedance of the speaker(2) is reduced.

So, your amp will put out less power with your single 8ohm cab than it would with two 8ohm cabs (which results in a 4ohm load). The only thing you can do wrong is operate that 4ohm minimum amp below 4ohms (e.g., hooking up three cabs, or two 4ohm cabs, or a 4ohm cab and an 8ohm cab).

In your case, using one of your 8ohm cabs or both of your 8ohm cabs is fine with that head.

It's not a "4 ohm amp." It's an amp with a 4 ohm minimum impedance load. It will work fine with a single 8 ohm cab, although it will output less wattage. It will also do fine with your two 8 ohm cabs, for a 4 ohm load.

Cheers,
Liam

Quick answer
 

MB200 into 8 ohms = 140W

MB200 into 4 ohms = 200W

Thanks guys! Your the best! Everybody had something I was looking for.