Anyone have a recommendation on how to set the polarity switch on SM 81's when used as overheads? There are 3 settings and I've been using the straight line setting, but I don't understand the the different settings and how they affect the sound when used as overheads. We use two overheads and follow the 3:1 ratio for placement.
The switch is not a polarity switch, The SM81 has a three-position low-frequency response filter controlled by this switch. You can select flat response, 6dB per octave below 100 Hz, or 18 dB per octave below 80 Hz. When close micing vocals or an instrument proximity effect takes place. This is an increase in low-frequency response. This filter may be used to compensate for proximity effect or to reduce low-frequency noise from stage traffic.
The SM81 also has a 10 dB attenuator that can be changed by screwing off the screen and rotating the ring under the screen. There are only a 0 and a -10 dB setting.
