this whole ohms thing...

Mike in Chicago · #1 08-12-2011, 05:32 PM

I've been playing a long time. Plug it in, play. never got into the electronics. I know...4 and 4 8 and 8 and so on. I've read about mismatched...I guess a 4 ohm head into a 8 ohm...I think. I've heard how "this amp really puts out at 4" stuff..is there a simple rule?

Thundar · #2 08-12-2011, 05:37 PM

Youve got it all bassackwards 8+8=4, 4+4=2, 8+4=2.67

Read the dang sticky : Ohms FAQ

Mike in Chicago · #3 08-12-2011, 05:45 PM

See what I mean? So with my two ampeg 4ohm bottoms (1x18 and 4x10) a 4 ohm head right?

A V4b which I also have, has a selector switch 2,4,8... into a single 4x10 4 ohm bottom is good? I know I'd switch to 4

Thundar · #4 08-12-2011, 05:48 PM

Well you should have posted THAT question in the first place! Hehehehehe
Your two Ampeg 4 ohm cabs will be a 2 ohm load on your head, and you didnt specify WHAT head youre using in the first scenario....so that particular head would have to be safe to operate at 2 Ohms.
In your second scenario, youre just fine....with the V4b you should be able to run whatever combo you want.

Mike in Chicago · #5 08-12-2011, 05:53 PM

“200 watts @ 8 ohms, 350 watts @ 4 ohms, 425 watts @ 2 ohms“

THAT'S the stuff that drives me crazy...my eyes glaze over.

So....when I get my V4b back from getting cleaned up...pick up another 4 ohm 4x10 I switch the selector switch to "2" right?

The refridg V4b bottom is a little heavy...and 8 ohms...it's a 1974 rig

Thundar · #6 08-12-2011, 05:57 PM

Mike, my buddy, youre making this a lot harder than it needs to be....LOL.
How many heads do you have? That V4b aint 350 watts, is it?
But anyways, if youre running "said" head with two 4 ohm cabs, then you will be getting 425 @ 2 ohms.

Mike in Chicago · #7 08-12-2011, 06:07 PM

Yeah...the V4b is 100...that I do know, the other Peavy mega is 350...but it sounds like a Peavy.

The Ampeg is gonna be my out head from now...now the big head? My progrock days are behind me.

I'd like to add another 4x10...to make 2 OR maybe buy 2 2x15's THAT would be a nice match for the V4b head. THICK.

Thundar · #8 08-12-2011, 06:12 PM

Oh, youre killin me! LOL
Is that a Peavey Megabass? Heck fire, that thing will run whatever you want it too, and be LOUD too! Slap a VT bass pedal in front of that thing, and hook those Ampeg cabs on up. I have a megabass myself and it IS a lil' sterile sounding, epsecially if youre used to a tube amp, but those Megas are workhorses! Send me a private message if you wanna know anything else, Bro!

JHAz · #9 08-12-2011, 07:06 PM

Quote:

Originally Posted by Mike in Chicago

“200 watts @ 8 ohms, 350 watts @ 4 ohms, 425 watts @ 2 ohms“

THAT'S the stuff that drives me crazy...my eyes glaze over.

So....when I get my V4b back from getting cleaned up...pick up another 4 ohm 4x10 I switch the selector switch to "2" right?

The refridg V4b bottom is a little heavy...and 8 ohms...it's a 1974 rig

If it's loud enough with whatever speakers you're using, you really don't have to worry about the amp's power ratings. But FWIW, the speakers' ohms measure the electrcal resistance of the speaker to the electricity the amp is trying to push through the speaker. With more resistance, the amp can't push as much power. Sorta like I can throw a baseball much farther than I can throw a ten pound medicine ball. The baseball weighs less and resists my throwing motion much less. That's why most amps have different power ratings at different impedances.

As long as your'e loud enough, impedance matching is the thing to "worry" about. And you've already gotten the straight dope on that.