Jumbo Sunshade - Ezine

Stereo Speaker Wiring Diagrams for 2-speaker and 4-speaker guitar and bass cabinets (2x10, 2x12, 2x15, 4x10, 4x12, 4x15)
 

[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.

 

2-speaker cabinet wired parallel with 16-ohm speakers
* Mono = Use first input only, both speakers for an 8-ohm total load.
* Stereo = Use first and second inputs, 1 speaker each @ 16 ohms (per input).
* Second jack only = 1 speaker @ 16 ohms.

 
2-speaker cabinet wired parallel with 8-ohm speakers
* Mono = Use first input only, both speakers for a 4-ohm total load.
* Stereo = Use first and second inputs, 1 speaker each @ 8 ohms (per input).
* Second jack only = 1 speaker @ 8 ohms.

 
4-speaker cabinet wired parallel with 16-ohm speakers
* Mono = Use first input only, four speakers for a 4-ohm total load.
* Stereo = Use first and second inputs, 2 speakers each @ 8 ohms (per input).
* Second jack only = 2 speakers @ 8 ohms total

 
4-speaker cabinet wired series/parallel with 8-ohm speakers
* Mono = Use first input only, four speakers for an 8-ohm total load.
* Stereo = Use first and second inputs, 2 speakers each @ 16 ohms (per input).
* Second jack only = 2 speakers @ 16 ohms total


What makes this series/parallel?  You have two sets of speakers wired in series and then combined parallel.  When running mono, you're running series/parallel.  When running stereo (or input 2 only), you're running series each side.
 
4-speaker cabinet wired series/parallel with 4-ohm speakers
* Mono = Use first input only, four speakers for a 4-ohm total load.
* Stereo = Use first and second inputs, 2 speakers each @ 8 ohms (per input).
* Second jack only = 2 speakers @ 8 ohms total

 

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