ProCo makes a pretty good sounding Bridging Transformer too. A bit cheaper than the Jensen, and for your son's band use, it will sound very fine indeed.
The box is very easy to build. You need:
1X XLR Female panel mount
2X XLR Male panel mount
1X project box
2X one lead toggle switch
1X Bridging transformer (You can make a REALLY cool box by purchasing a Bridging transformer that has 2 output leads! Just
add 1 more Male XLR and 1 more toggle switch. A two lead output bridging transformer in this case will give you 3 possible outputs from the mic.
About 2' of 24 guage wire
Mount all connectors and toggle switches and transformer. Lable one toggle switch Direct, one Leg 1, and if you are using a dual splitting transformer, the other Leg 2.
Lable XLR Male jacks the same as toggle switches.
Twist together and tint with solder a long enough length of wire with the Transformer input wire to go from the Male XLR to the Direct Female XLR. Solder first to the Female XLR jack following this wiring scheme:
Ground = Pin 1
Hot (+) = Pin 2
Cold (-) = Pin 3
Next, wire the Pin 2 and Pin 3 leads of the combined wire pair to the Direct Male Jack. DON'T wire the ground wire yet, just 2 and 3. Now, run the ground wire to your toggle switch that is labeled Direct and apply it to one one side. Take another short length of wire to run from the other side of the toggle switch to Pin 1 on the Male Direct XRL jack. In case you are wondering why the toggle switch in on the ground, this is so that you have a ground lift for the Direct line. All Legs will too have ground lifts. This is a very cool feature for a number of reasons and is something you should not do without.
Next, wire the Transformer output lead for Hot and Cold to Leg 1 Male XLR jack Pin 2 and 3. Run the ground lead to one side of the toggle switch labeled Leg 1, and use a short length of wire from the other side of the toggle switch to the Leg 1 Male XLR jack Pin 1. Now you have your Leg 1 ground lift.
There you go!!! You are now the proud owner of a transformer isolated microphone splitter with seperate ground lifts on the Direct and Leg 1 outputs. I would recommend using the Direct output to whatever needs to sound the best because this is just a Direct feed and the audio is not effected by the transformer. Usually you would use this to feed the front of house mixer.
If you hook it all up and get some weird humming and what not, start lifting the grounds via your Direct and Leg1 ground lift toggle switches. Try one, then try the other. Worst case, both will need to have the ground lifted.
Errrrrrrr.....I might be just as simple to buy the proper connectors to use a channel on the audio snake (if they are using one) and use a Pre Fader Aux send from the house console to run the on-stage monitor......
