I Have a Question on a 4x12 Cab

Sp8ctre

Sp8ctre

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Look at the picture and tell me if I understand this...If I plug in to the LEFT/MONO and the switch is to the right I'm at 16 Ohms and with the switch to the left I'm at 4 Ohms. If I'm plugged into the RIGHT or LEFT with the switch to the left I'm at 8 Ohms on either side...

What I'm getting at is in the 8 Ohm position each sides output will be only two of the four speakers and I'll have an 8 Ohm load on my amp...

Correct?

20181002_135447.jpg
 
i replaced the similar one of those jack plates, on my Marshall, with one of these when the switch failed.
D6596AF6-681F-4CEC-BD5D-96961F34FFA1.png
Minor surgery was required, but way easier to deal with.
 
Sp8ctre said:
Now I'm confused again...can I use just one of the jacks as 8 ohm in some way?
Click to expand...
Flip the switch as the arrow indicates. Plug in to the circled jack. That should get you one pair of speakers wired for a load of 8 Ohms.
If you have a multi meter around, follow the above, but instead of plugging the speaker cable in to the amp...set your meter to read resistance/ohms, touch the negative to the sleeve, and positive to the tip...should read 6-7ish ohms.

A0056BB4-F307-45B9-99AC-EB60A788FE70.jpeg
 
Sp8ctre said:
So what happens with this configuration when you only plug into the right side 8 ohm jack alone?
Click to expand...
You get two speakers wired as an 8 Ohm load. Just less confusing to get there.
Test your cable with a multi meter under different settings on your cab. You’ll see...it will always read a little under, but not so far as to be mistaken for the next common impedance down.
 
I get how the whole thing gets the ratings. four 16 ohm speakers in parallel and you have 4 ohms. Then two sets of 16 ohms in parallel wired in series and you have 16 ohms.

So if you have two sets of 16 ohms wired in parallel and separated from each other you have 8 ohms at each jack.

So if I plug a cable into one side of the 8 ohm stereo and plug my amp into the other side of the 8 ohm stereo am I
okay load wise on my amp, but only playing through two speakers????????????
 
Thatbastarddon said:
Flip the switch as the arrow indicates. Plug in to the circled jack. That should get you one pair of speakers wired for a load of 8 Ohms.
If you have a multi meter around, follow the above, but instead of plugging the speaker cable in to the amp...set your meter to read resistance/ohms, touch the negative to the sleeve, and positive to the tip...should read 6-7ish ohms.

View attachment 18400
Click to expand...

If that is true then why is it a 4 ohm load if the switch is to the left and 16 ohm if the switch is to the right? Is there something going on when you jack into both inputs that is making it 8 ohms per side?
 
Sp8ctre said:
So if I plug a cable into one side of the 8 ohm stereo and plug my amp into the other side of the 8 ohm stereo am I
okay load wise on my amp, but only playing through two speakers????????????
Click to expand...

Answer:
Thatbastarddon said:
Flip the switch as the arrow indicates. Plug in to the circled jack. That should get you one pair of speakers wired for a load of 8 Ohms.
If you have a multi meter around, follow the above, but instead of plugging the speaker cable in to the amp...set your meter to read resistance/ohms, touch the negative to the sleeve, and positive to the tip...should read 6-7ish ohms.

View attachment 18400
Click to expand...
 
Sp8ctre said:
If that is true then why is it a 4 ohm load if the switch is to the left and 16 ohm if the switch is to the right? Is there something going on when you jack into both inputs that is making it 8 ohms per side?
Click to expand...

That’s why I criticized the labeling of the plate.
Looking at your jack plate, the switch positioned to the right(as pictured) would indicate that “mono” mode is engaged. In this position the jack on the right(labeled left) is for a 16 Ohm load.
Also with the switch to the right, the jack on the left(labeled right) should present a 4 Ohm load.

Now when you flip the switch to the left you should be in stereo mode. Each jack should present as an 8 Ohm load.

But the labeling on that plate is so...vague/backwards(but it is correct if you envision a view from the front). I would still use a multi meter to learn what is what...just to be safe.
 
Well...when all else fails due to what I consider strange labeling break out the ohm meter.

The jack labeled LEFT/MONO is either 4 ohms or 16 ohms based on the position of the switch.

The jack labeled RIGHT is 8 ohms when the switch is to the left.

If you jack into the one labeled RIGHT, but have the switch to the right it becomes 32 ohms...
 
Thatbastarddon said:
That’s why I criticized the labeling of the plate.
Looking at your jack plate, the switch positioned to the right(as pictured) would indicate that “mono” mode is engaged. In this position the jack on the right(labeled left) is for a 16 Ohm load.
Also with the switch to the right, the jack on the left(labeled right) should present a 4 Ohm load.

Now when you flip the switch to the left you should be in stereo mode. Each jack should present as an 8 Ohm load.

But the labeling on that plate is so...vague/backwards(but it is correct if you envision a view from the front). I would still use a multi meter to learn what is what...just to be safe.
Click to expand...

Sound logic, but wrong...
 
...and the jack labeled LEFT only becomes 8 ohms if you have a jack plugged into the RIGHT and the switch to the Left.

Anyone NOT confused yet?
 
Sp8ctre said:
...and the jack labeled LEFT only becomes 8 ohms if you have a jack plugged into the RIGHT and the switch to the Left.

Anyone NOT confused yet?
Click to expand...

My Marshall was labeled clearly enough(and functioned differently than yours), but when it failed I was happy to cut out a small section of the rear panel to accommodate the plate I posted earlier.
Saves me from worries incurred when loaning out the cab...it’s pretty straight forward, and functions as clearly labeled.
 
Thatbastarddon said:
My Marshall was labeled clearly enough(and functioned differently than yours), but when it failed I was happy to cut out a small section of the rear panel to accommodate the plate I posted earlier.
Saves me from worries incurred when loaning out the cab...it’s pretty straight forward, and functions as clearly labeled.
Click to expand...

Your jack is more clear, but I assume you only get 8 ohms from the left jack when there is something plugged in the right jack?
 
Sp8ctre said:
Well...when all else fails due to what I consider strange labeling break out the ohm meter.

The jack labeled LEFT/MONO is either 4 ohms or 16 ohms based on the position of the switch.

The jack labeled RIGHT is 8 ohms when the switch is to the left.

If you jack into the one labeled RIGHT, but have the switch to the right it becomes 32 ohms...
Click to expand...
Well, at least my scribbled picture was correct to get you 8 Ohms:BH:
 
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