ohm question

[jerseydrew]

At the moment I'm using my Mesa MkIV head with my Marshall 1960A 4x12 cab. The amp has one output for 8 ohms and two outputs for 4 ohms. Obviously I'm using one of the 4 ohm outputs into the Marshall 4 ohm input.

My question is, I was thing about hooking up another cabinet. More specifically, my Mesa 2x12 cab (8 ohms). I want to use both cabs at the same time. Is this possible?

My Mesa cab is 8 ohms and my Marshall can be either 4 ohms or 16 ohms. Can I hook both up to my MKIV? I would assume I would have to use both 4 ohm outputs on the amp.

I don't want to screw anything up. Will I have a problem?

 

[sbalderrama]

An 8 and 4 in parallel will end up with a resistance of 2.67 ohms. Mesa tends to say in alot of their manuals that some amount of mismatch won't hurt their amps, so it might be ok if you plugged them into the 4ohm jacks, but I don't make any claims to being an expert on this so I could be wrong. I don't know exactly what you end up with if you plug the 8 into the 8 ohm slot and the 4 into one of the 4 ohm slots. AdmiralB could probably answer that.

The other problem though is that the 4 ohm cab will be receiving double the power of the 8 ohm cab, so unless you're 4 ohm cab is inefficient you will probably have sound level mismatch.

 

[jerseydrew]

OK, new situation. My main point is that I really want to use 2 speaker cabs. I like to separate the cabs on each side of the room. I have a Mesa Vertical 2x12 cab which is 8ohms. I also have a Mesa 1x12 cab which is also 8 ohms. I would assume that I could plug each cab into each 4 ohm output in the amp.

Does it matter that one cab has 2 speakers and the other cab has only one speaker? Each cab is 8 ohms.

 

[sbalderrama]

Does it matter that one cab has 2 speakers and the other cab has only one speaker? Each cab is 8 ohms.

Not really. The power should split evenly between both cabs, so the double speakers individually are not driven as hard as the single one will be. Volume balance should be pretty close I would think. Certainly no reason not to try that setup.

 

[user 7737]

**** ! complicated !

i have a 4x12 cab :

mono 4 or 16 ohm
stereo 2x 8 ohm

it means i can plug my caliber head (1x8 ohm and 2x4 ohm outputs) in the cab like this :

4 ohm output -> 4 ohm input mono

or

2x4 ohm outputs -> 2x8 ohm inputs stereo

but in fact the sound will be exactly the same ! am i wrong ?

second question what if i want to use a second cab with 2x12 8 ohm speakers ?

thank you !

 

[jerseydrew]

I'll double check to make sure my 2x12 is 8ohms. I'm 99% sure it is.

I totally changed up my speaker cabs.

Here's what I'm doing right now. I'm using a 16 ohm Marshall 4x12 cab and a 8 ohm Boogie 2x12 cab. Both cabs are going into my two 4 ohm outputs of my MKIV head.

According to some people on TGP, it's mathematically close enough for a Boogie.

It sounds awesome and I'm only playing in my basement