Comms Headset Wiring 5 Pin Question

[Tilski]

Hello,

 

I'm new here. Been a while since I've used a forum. I'm just after another pair of eyes please. I've been trying to interface a Canford TecPro comms system with 3 JVC CCU's in a small college studio in the UK. The headsets will all be 5 pin XLR on the camera cradles. The operators can hear the gallery and any music played through the sound mixer. BUT they cannot talk back to the gallery on each other. I have the wiring diagram of the headsets and the pinouts of the camera cradle. How would you guys do it?

 

This is the PDF of the headset wiring. I have chopped the connector off and want to solder the wires to a 5 pin XLR: https://drive.google...iew?usp=sharing

 

 

This is the 5 pin XLR on the back of the camera: https://drive.google...iew?usp=sharing

 

And finally some more info on the headsets: https://drive.google...iew?usp=sharing

 

Many thanks

 

Atila

Edited February 9, 2021 by Tilski

[sandall]

TecPro systems use dynamic mics - your headsets have condenser mics, which need DC powering (they probably expect to see around +3v to +4.5v). There are cheap(ish) compatible headsets around & there is a wealth of info in various Blue-room threads & online (search for "TecPro-compatible headsets"). Alternatively, if you are happy with a soldering iron you could make a simple bodging-box for each headset (also covered in BR threads.)

[Tilski]

Thank you. I will have a look through and see what I find. I'm thinking that there must be a source of power already on the camera cradle that I might be able to use.

[sandall]

The green wire on your headsets is mic power (the spec sheet suggests +1.5v is sufficient), but whether you find power on the cameras or use an AA battery you will need a capacitor in series between the mic and the comms unit, to block this voltage. You may also need a way to attenuate the mics, as condenser mics are usually much louder than dynamic ones.

[neilalexrose]

 

This is the PDF of the headset wiring. I have chopped the connector off and want to solder the wires to a 5 pin XLR: https://drive.google...iew?usp=sharing

 

 

This is the 5 pin XLR on the back of the camera: https://drive.google...iew?usp=sharing

 

And finally some more info on the headsets: https://drive.google...iew?usp=sharing

 

 

Looking at the pinout of the headsets, I would probably check the 'mic -' path, and how that relates to the PTT switch. I would use a multimeter set so that it will read the 2.2kohm impedance referenced in the 3rd pdf linked to. Put one probe on the mic +, and then use the other probe on the 'PTT' wire to see if you get a reading, and then on the 'Ground' wire checking the same. With the probe on the PTT line, you'll probably need to press the button on the headset to actually get a reading. (I've seen this before when fixing Motorola headsets with the dual 2.5mm and 3.5mm jack connectors for newer handsets. The PTT switch is a push to make switch to compete the microphone circuit.)

My hunch is the the ground wire is just for the speaker, and the PTT wire is actually the mic -. If the latter is the case, you will need to decide if you bypass the PTT switch in the headset so the mic is always live, or see if it works ok as a PTT with the tech pro system.

 

Depending on the overall headphone level and how the volume control on the comms system behaves, you may also need a resister in series on the speaker circuit. From memory the standard Techpro headsets are 200 ohm for the microphone and 400ohm for the earphone. With those headsets being 32ohms, the volume might be a bit loud in the ears, or may only give you a tiny adjustment before it becomes very loud.

Also the headsets look like they will be in mono, so speaker + connects to either pin 4 or 5 on the camera cradle (I suspect pin 4 and pin 5 is not connected.)

 

 

I'll defer to Sandall's post on the need for power, as the 1.5v operating volume for the microphone is something I've never had to worry around in my dealings with comms systems.

Edited February 11, 2021 by neilalexrose