Logic doesn’t always have to be related to computers or programming—it can be very basic and hardware-related. Here’s a simple implementation of basic logic, inspired by everyday needs.
Many times, we want to use the same speaker cab in either stereo or mono, depending on the situation. On top of that, we might have a limitation where the load impedance can’t go below 8 ohms. By adding a third input jack—one of the common TRS types with normalizing switches on all contacts, often found in MI gear—we can wire it to connect two 8-ohm speakers in series instead of parallel (which is actually simpler, very common, and only needs two jacks). TS connectors would be sufficient here, but TRS connectors are everywhere anyway, so we’ll use those.
This idea can be easily scaled—for example, in a 4×12″ cab with four 16-ohm speakers. Just wire two 16-ohm speakers in parallel wherever the diagram currently shows a single 8-ohm unit.
A cab with two 16-ohm speakers is even simpler and commonly used to automatically switch to an 8-ohm mono setup by switching the elements in parallel, using just two input jacks. We do not cover that setup here.
Note: If mounted on a metal plate, the jacks must have an isolated sleeve contact—that is, the act of mounting the jack must not connect the sleeve terminal to the chassis.
Did it go like in Strömsö?
Yes, it did. The practical implementation is, even when measured, as expected. We apologize for the serial number though…
Labeling is the only thing missing now.
Enjoy the tone—and the ambience!