I think your RC results have something in common with the LG V60 results I posted here earlier.
My first quick test. It does not seem to be able to calibrate the microphone yet. No Sub. Default RC settings. Mic fixed and measured in an unoccupied room. 1. LG V60 Built-in mic 2. IMM-6 (LG V60 ) 3. IMM-6C (LG V60 ) 4. IMM-6C + Extension cable (Galaxy tab S8 plus) I'll...
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In my tests, when I connected the IMM-6 to the LG and measured the sweep, I found a noticeable difference from the built-in microphone: with the IMM-6, the curve peaked at 1 kHz and became mountainous.
Therefore, the low frequencies are likely to be boosted in the RC to compensate for this. Unfortunately, due to my lack of knowledge, I do not know the cause yet.
View attachment 10086
View attachment 10087
This problem does not happen with my IMM-6C.
This is a sweep measured on another day with a Galaxy tab s8 plus + IMM-6C, which is clearly different from the LG results.
View attachment 10089
(Edit: I reposted this because I made a mistake with the image.)