[For
more information on series, parallel, ohms - or for standard speaker
wiring diagrams, please go here.
For more stereo speaker wiring diagrams,
please go here.]
You have to be careful
when you use switches because if they're not labeled correctly (or if
you just forget to check) you could easily mis-match amp and speaker
ohms. Switching jacks are scary because these teeny little
connectors are responsible for maintaining (or breaking) a good
connection from the amp to the speaker. Also, just like having to
be sure which output to Use First on your amplifier; you also have to be
sure which input jack to Use First on your stereo speaker cabinet (so
label them well!).
Both switches AND switching jacks should be used with caution when
hooking up tube amplifiers to stereo cabinets.
Below are switching stereo speaker wiring diagrams for 2-speaker
and 4-speaker cabinets. "Switching stereo" means that when the
mono jack is used, all speakers in the cabinet (combined ohms) are used;
when the second jack is employed, it switches the circuit, cutting it
into two independent circuits.
Any 2-speaker or 4-speaker cabinet can be rewired as a switching
stereo cabinet. Typically this would be 2x12 and 4x12 cabs, but
these circuits also apply to 8", 10" and 15" speakers. You need
two 1/4" phone jacks, but one of them must be a stereo switching jack.
Here is the Switchcraft 14B stereo switching jack:
It has 5 connection points. Two of these points are contacting
(one each) the Tip and Sleeve connectors. These two sets are
circuit connection points that BREAK when a 1/4" phone plug is
inserted into the jack. It helps to keep that in mind when trying
to visualize different uses for a mono or stereo switching phone jack.
Here is how the stereo switching jack is represented in my diagrams:
For these circuits, a mono (non-switching) phone jack is used for the
first input and a switching phone jack is used for the second input.
For mono use, just plug into the first input jack, which uses both or
all four speakers in the cabinet. For stereo use, leave the first
plug in (obviously) and plug into the second jack, which switches the
speaker cabinet into two separate circuits. Unplugging the
first/mono input will have no affect on the second input.
Also, it is assumed that 1/4" MONO
(TS) speaker cables are being used.
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