XLR Dual A/B box

[lowell]

I'm just starting to design a box to do this. A customer wants it and cannot find such a box on the market. 1 xlr in and 2 xlr outs.

I was initially thinking of using the CD4053 but this chip has a max switching voltage of 10vDC.. therefore phantom power will be out of the question. However what if I was to ac couple the ins/outs of the xlr jacks and connect the phantom power "outside" of those? This way the phantom power would never reach the pins of the CD4053. Does this make sense?

My initial thought is to use a typical 9v supply, jfets for the signal switching, and a latching mechanical switch of sorts for the 48v phantom power. I believe I'll need to be able to switch 6 connections with the stomp of 1 switch: 4 balanced signals (pins 2/3 of xlr cable times 2) and 2 LEDs. I'll just keep the grounds (pin1) hardwired. I guess potentially this could lead to grounding issues, maybe I should keep the grounds isolated.

This HEF4051B looks like it may work the best and allow me to keep the grounds of both xlr outs isolated. It's 8 switches. The supply is 3v-15v and it's switches are rated for up to 15v so this should be good for switching 9v to and fro the LEDs.

Any thoughts anyone?

[52 Bill]

Wouldn't a 3.P.D.T. do what you are planning? Two poles for the audio and the third for the led.

[loudthud]

Dealing with phantom power is going to be a nightmare and I think it will interfere with any ground lift provisions you might want to provide. The easiest thing to do would be to isolate each XLR with a transformer, then you can switch the cold side of the transformers with whatever you want. Connect the phantom power as required with slide switches.

CD4053s might be too noisey. The HEF4051B looks the same as a CD4051, a 1 to 8 switch, not what you want.

[lowell]

Wouldn't a 3.P.D.T. do what you are planning? Two poles for the audio and the third for the led.

I guess that this may work. Only drawback is that the xlr grounds will not be isolated. I may try this option first and see if any grounding issues arise. Thanks!

on second thought there is also a 1/4" signal that needs switching simultaneously with the stomp of 1 switch for all. I think I'm stuck with an IC for switching or relays.

LT I will need to switch the xlr, 1/4", and LED. Do you think relays are a must here?