Dumb question for new 4x12 owner

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Green72

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Never owned a 4x12. Just picked up an old Marshall 1960a.

The cabinet has a 4ohm and 16ohm jacks for inputs.

Which output of my amp do I use? 4, 8, 16?

thanks
 
Ok, so are you trying to run the cab stereo? if so use 4 ohm tap.
If you are using cab mono (one speaker cable) match the impedance of the amp to the speaker input, or use 4 ohm from amp. You will always be safe doing that. But i would play 16 ohm out on amp into 16 ohm input which i assume is on the left.
 
however, that said. because you don't know the history of that cab, I would use a multimeter and plug one jack into cabinet, and then measure ohm of the tip and side at same time. That will give you your ohms. If it is 5 that equals 4ohm. if it is 12-15, we are looking at 16 ohms.. I think 8 usually registers pretty accurately, but you get the idea.

That said, if you want to run 4 ohm out of the amp, you will be safe no matter what.
 
Always match if you can. 16ohms out of the amp go into 16ohms into the cabinet.

IF you cant match, then use a lower ohms from the amp into higher ohms on the cabinet. so 4ohms from the amp can go into 4, 8 or 16ohms on the cabinet. 8 ohms from the amp can go into either 8ohms or 16ohms on the cabinet.

does it have any labeling on the back as far as series? parallel? mono? stereo?
 
Bash_Man said:
Always match if you can. 16ohms out of the amp go into 16ohms into the cabinet.

IF you cant match, then use a lower ohms from the amp into higher ohms on the cabinet. so 4ohms from the amp can go into 4, 8 or 16ohms on the cabinet. 8 ohms from the amp can go into either 8ohms or 16ohms on the cabinet.

does it have any labeling on the back as far as series? parallel? mono? stereo?
Click to expand...
It has a switch that lets you change it from stereo to mono. It's in mono right now.
 
Green72 said:
It has a switch that lets you change it from stereo to mono. It's in mono right now.
Click to expand...
Ok so those will differ in ohms for sure. Definitely use it in mono. I think stereo might give you a phasing issue... I could be wrong.
 
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Green72 said:
Never owned a 4x12. Just picked up an old Marshall 1960a.

The cabinet has a 4ohm and 16ohm jacks for inputs.

Which output of my amp do I use? 4, 8, 16?

thanks
Click to expand...

Most cabs only have a single connection option for all four speakers in mono, but the 1960a has two.

To use all four speakers with a single amp head, select the "MONO" setting on the cab, and from there you have two "best" options:

1. Amp head 4 ohm out -> cab 4 ohm input
2. Amp head 16 ohm out -> cab 16 ohm input

NEVER connect a single amp's power section into both cabinet input jacks when the cab is set to MONO. If you do, you'll probably destroy your amp, or at best you'll blow a fuse.


With the Marshall 1960a cab, you can use two heads in stereo if you want. To do that, set the cab to "STEREO" and from there:

1. Left Amp head 8 ohm out -> cab Left 8 ohm input
2. Right Amp head 8 ohm out -> cab Right 8 ohm input
 
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