"After the fact" microphone pair matching-
To check the match between the two microphones you can place the two mics immediately adjacent to each other facing the same direction and record something. The aim is to get identical sound into both channels. A mono result from the two essentially. Pink noise is a good thing to record to check this. Static from a radio can substitute.
To match the two outputs as closely as possible, import the resulting files into your editor. Invert polarity of one channel and sum the two to mono. By inverting the polarity of one channel you set them up to cancel-out each other. If level and response were absolutely perfectly matched the summed result would be silence, but it never will be that perfect. Adjust gain of one channel verses the other with the goal of making the levels of the two channels as similar as possible. The closer in level they get, the lower the level of the summed output will become. Carefully adjust gain to achieve the lowest summed output level possible. Note the amount of gain used. That's what you'll need to apply each time to bring the signals from the two mics into close level match. But even if doing that, I'd still make any final balance adjustment to each recording by ear as needed.
Taking that matching one step farther-
If there is a significant frequency response mismatch, you can also play with EQ'ing the channel that's more problematic to more closely match the other. You can use the same inverted polarity trick used to do the gain matching adjustment, only this time adjusting EQ on the "less good" channel so as to match the other channel. Like before, the goal is to adjust things until you achieve the maximum cancellation possible (quietest summed output). Alternately, you might use an EQ with a matching EQ routine that automatically adjusts the EQ of one source to match that of the other. Once you've done that, save or otherwise record the EQ and level settings so you can reapply them each time you start editing recordings made using that particular pair of mics.
Microphone matching actually involves getting three things as identical as possible: Output level, frequency response, and phase. Making adjustments to match phase closely is possible but beyond the scope of this post. But if doing the EQ matching thing, you can try switching between minimum phase and linear phase EQ modes to determine if you can achieve more cancellation with one or the other. Minimum phase EQ will affect phase as well as level. Linear phase EQ will only change level in the affected region. That's getting pretty involved with it, but once done the results can be applied to any recording made using that pair of mics (as used in a typical stereo mic pair configuration of course)
If all this sounds like Greek to you (assuming you don't speak Greek), or is simply to much to bother with, just adjust levels to match by ear afterward.
Topic: CA14 different sound level in left and right channel (Read 5218 times)