Marshall jack plate wiring for 4x12 stereo/mono

  • Thread starter Thread starter The_Kid
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The_Kid

The_Kid

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I have it setup wired at 8 ohms per side stereo. As per the avatar instructions.

What I want to know is, I have a switch on the back to switch to mono if I choose.

Do I have wire anything different/additional to take advantage of this? Or does the switch flip the circuitry enough that its mono at 16 ohms just flipping the switch. :confused: :confused:
 
I'm assuming that it is wired like it was stock, if you use the 16 ohm input, and switch to mono, it should be 16 ohm's without doing anything else - Jim
 
If you have, or can borrow a multimeter, you can measure the ring and tip of the speaker cable with the switch set to mono. The usual thing with those back plates are that one input is 16, the other 4.
 
ok, I was planning on having my buddy come over and help. THe only time he has is tomorrow morning, and I'd rather not take up too much time on his thanksgiving morning as he is working like 60+ hours a week this time a year.

if I need to wire anything else, i'd rather have it done before he gets here.

I have 2-16ohm speakers wired in parallel according to the avatar site. I'll check the cable like you suggested, as soon as I can.

THanks for the help guys
 
ke2":3vkqslxt said:
If you have, or can borrow a multimeter, you can measure the ring and tip of the speaker cable with the switch set to mono. The usual thing with those back plates are that one input is 16, the other 4.
Click to expand...

Go buy a multimeter! They're cheap(or can be), and indispensable. You will need one throughout your life.

To test the impedance of your cab, you can simply put a cable in, and put the probes on the other end, across tip and sleeve.
 
ke2 is right, you better look at this, THIS is what you will actually read at the meter. Its never what it says on the jackplate { not that I have ever seen in 25 years, I'm not sure why, apparently impedance and resistance are slightly different when you measure it that way} I always thought impedance was the measurement of resistance of a given circuit. I'm still not totally clear on why its different. Olaf would know, I'm sure
 
my buddy brought one over, every jack reads exactly as it should...just a touch less than the jack reads.

when in stereo: both jacks read between 7.2-7.5 ohms

When in mono: the 16 ohm jack reads right around 14.5
the 4 ohm jack reads pretty much dead nuts to 4.
 
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