Wiring a Shure PG30 Headset Microphone

I recently tried to rewire a Shure PG30 headset microphone so that it could be connected directly to a computer sound card via a stereo mini plug.  I had limited, but insufficient, success after some amateur tinkering.

There is a PG30 datasheet (PDF) and some instructions by Shure on using a similar mic as a wired microphone.  Note that you can permanently damage your microphone by incorrectly wiring the mic and/or reproducing any of the modifications described in this post.

The Shure-provided instructions are to wire:

  • pin 1 of the TA4F connector to the sleeve of the stereo mini plug
  • pin 3 of the TA4F connector to the signal part of the plug
    • I wired pin 3 to the “ring” part of the plug
    • I possibly should have wired pin 3 to the “tip” part of the plug

After this step, I was able to record a very weak microphone signal when turning up the gain of my soundcard.  The weak signal led me to believe that I needed to supply power to the built-in preamplifier.

Supplying external power is a great way to permanently damage the microphone, so do so at your own risk.  The PG30 cannot use the 48V phantom power supply that a standard condenser mics would use, so I used 4 AA batteries to supply about 6V.  Here, the connections were:

  • pin 2 to +6V
  • pin 1 to ground

The resulting microphone signal looked odd, like it was modulated by a slow carrier wave, and it was quite noisy.  I placed an audio isolation transformer between the microphone output (pins 1 and 3) and the soundcard input (the sleeve and the ring), which provided a much cleaner signal.

However, the signal was still too noisy for my application, noisier than the signal obtained from the output of the Shure wireless system.  This noise may be due to my quick-and-dirty wiring, or perhaps the Shure wireless system adds additional filtering.  From what I was seeing, I would feel comfortable using the modified PG30 as a headset for internet telephony, where some background white noise isn’t too distracting.

If you have luck with a conversion or any additional suggestions that may be of use to others, please feel free to leave a comment!

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