Orion I/II Mic Gain Pot Adjustment

(posted by K8QH to the reflector)

On the bottom side of the Orion II just behind the front panel mic connector is a hole in the bottom cover giving access to a trimpot gain control on a mic preamp circuit board. This control is independent of the digital gain control accessed through the menus.

I found my Orion II mic (using a Heil dynamic mic) had very low gain (shouting was required) until I just touched the trimpot with a small screwdriver. Instantly, normal mic level was restored. After noting the position of the trimpot setting, I swept the pot's adjustment back and forth and it's been stable since. (I'm guessing it was a dirty spot on the trimpot and not a fractured solder connection on the preamp board.) The Heil mic sounds great now that the internal Orion II preamp is working properly.

The preamp circuit is not included in the on-line Orion II schematics but can be found in the on-line Orion I schematics. This preamp adjustment is also useful if you use a dynamic mic vs. an electret mic to best adjust for S/N depending on the microphone.


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