Crown Audio by Harman




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How do I make a CM-311AE or CM-312AE hard wired?

I've certainly enjoyed reading your articles in the trade press over the years. I just bought a CM-311AE without understanding that it wasn't fully terminated. I need a way to rig power to it so it can be used in a wired configuration. I could use a 9V battery.
John Etnier, Studio Dual

I have a CM-311AE headworn mic with a mini XLR connector. How can I use it with my DJ mixer?
Frederick Hart Entertainment

Reply: To run the CM-311AE or CM-312AE off a 9V battery, you need a 9V battery clip, a 1/4" mono phone plug, a 4.7 microfarad electroytic capacitor, and a Radio Shack 1/4"-jack-to-A3M XLR plug adapter/transformer (part no. 274-017). Frederick, remove the mini XLR connector. The wiring to convert a CM-311AE to hard-wired is shown below. Plug the phone plug into the Radio Shack adapter/transformer (impedance-matching adapter). Plug the XLR end of that adapter into your mic input with phantom power turned off.

 

In the diagram, you can replace the 9V battery with a 9V DC power supply. Many of these supplies are not filtered well to prevent hum. Here's a filter circuit you could add to the 9V DC supply to reduce its hum: