I will build a simple passive signal multiplier to multiply single output into several outputs. This multiplication will involve 4 x (1 input mult. 3 outputs). This multiplier switcher concept is inspired from Kristian Blåsol which the original schematic design is made by Nicklas Rönnberg.
Here I have made some modification of the original multiplier i/o layout to reduce the number of un-used input jacks; original =16 jacks total at single input, multiple 8 outputs max, mine = 16 jacks total at single input, multiple 12 outputs max. This is done by multiplying each single input jack with 3 outputs set and the 3rd output from each set has a physical switching mode to the second input jack set to enable another 3 output jack from the second input set to have the same signal from the first input jack when there is no second input jack inserted. The ‘switching’ mechanism only can be done with three pins audio jack female type; ground, tip, tip (switcher), which is pretty standard available from any online electronic store (including Ali Express).
This multiplication circuit version will be simulated via circuit simulator software, Qucs to ensure that our circuit will works as we expected virtually before soldering them together. The diagrams as below. Note that, when the second male input jack inserted into the second input, the female input tip contact will be pushed upward by the second input jack tip and release (open) the contact between female input tip contact and female input tip-switcher (triangle). With this design, you will only be left with four un-used female input for full multiplication output from single male input jack from 4(1×3) system.
You may add a Schottky diode at ground rail to avoid reverse current if you accidently patching things wrongly. I will label the I/O and practice to patch things accordingly.