On 09/11/2015 01:21 PM, James Anthony Enda Bates wrote:
Hi everyone, I have a quick question about calibrating a Soundfield MKV. At the moment the test tone oscillators are coming in with the W channel about 3.5 dB lower than X,Y, or Z (these three channels are within about 0.5 dB of each other).
It's late and I've had a long day, but isn't that the expected W gain for classical Ambisonics?
So obviously the best thing would be to return the unit to get it calibrated as it's probably due for one; and this has been noted before on this list; http://sursound.music.vt.narkive.com/UtLGYHeC/sursound-level-alignment-of-soundfield-microphones However, my question is, if we know what the gain mismatches are based on the test tone output, is it sufficient to just apply gain adjustments to the b-format recordings based upon these Test Tone signal levels? Or is there a possibility that the test tone channel levels, and microphone channel levels could differ?
The problem is not the B-format output. B-format is very robust wrt small gain mismatches - say your Y is 3 dB down, all it does is make the image a little less wide.
IIUC, the problem is in the individual capsule gains - if one capsule is off by 3 dB (which would be a catastrophic mismatch), _all_ output components will be totally warped.
The capsule EQs might have similarly severe consequences, leading to weird direction-dependant coloration.
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