a 12b is used for the output jack and utilizes the ring contact to create a path to ground engaging the battery when a mono plug is inserted into it. the reference i made above is strictly talking about the OBEL. it needs a TRS stereo plug for the send and return sides. however with a 12b jack when the TRS stereo plug is removed it breaks the OBEL signal, so when you flip the switch to the OBEL there will be no sound. Flip the switch back to the non OBEL side and the guitar will have signal and sound. on the other hand with a 14b the switching contacts have a jumper between them that shorth the tip and ring together and send signal across the tip and ring when no TRS stereo plug is in the OBEL jack. either side of the OBEL switch with no plug inserted in the OBEL will have the normal side of the switches signal. put a plug into the OBEL 14b and the shorted contacts break and Tip and RIng work exactly like a 12b.
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