To achieve optimal modeling accuracy with the Sphere system, the microphone preamp gain should be set equally on both channels. Ideally, the gain should be within +-0.1dB, although the Sphere algorithms are designed to be relatively insensitive to mismatch. Generally, a mismatch of +-1.0dB is fine in most situations, if optimal accuracy is not required.
To calibrate the input channels on a fully analog mic preamp with continuous gain adjustment:
- Connect the microphone to the preamp as previously described and enable phantom power.
- Place the mic with the front pointing at your sound source.
- Create a stereo track in your DAW, and assign your preamp’s output channels as its inputs. The 1-Front and 2-Rear channels correspond to the front and rear capsules, respectively. When speaking into the front capsule and monitoring that track, you should hear significantly more level on the MIC 1 channel. If that is not the case, swap the inputs on the mic preamp.
- Set the preamp’s MIC 1 channel gain to an appropriate level for your intended sound source.
- Set the CAL/ON switch to the CAL position on the mic. The LEDs flash slowly in calibration mode, and the mic now outputs the same signal on both channels.
- Click the gear icon under Setup on the lower-left corner of the plug-in.
- Set the gain of the MIC 2 channel to match the gain of MIC 1 using the Level Calibration Meter. If it is not possible to match the levels within 0.1 dB, press the AUTO CAL button on the Setup page to better match the levels.
- When finished, set the CAL/ON switch to the ON position on the mic. The LEDs light solid to indicate it is configured for normal use.
See the Preamp Calibration section in the Installation and Configuration chapter in the Sphere Hardware and Software Guide for step by step information.