Problem with Mac OS vs IOS working with Signalscope X pro

crawford

I have downloaded the Signalscope X Pro onto both my iphone X (iOS 16.6) and new Macbook Pro M3 (OS Sonoma 14.1). I have two mics: micW i436 and micW i437L. Both mics record an ambient noise of 50-60 dB on the iphone after calibrating to 94 dB with a Galaxy Audio CM-C200 calibrator. The Macbook Pro only takes the i436 mic and after calibration it records room ambient noise between 90-100 dB. So, same room, same mic but radically different Sound Meter measurements. Are these micW mics not compatible with the new (2023) MacBooks or is the microphone in the MacBook not working correctly, or what? I get the same 90-100 dB simply without the micW mic plugged into the MacBook.

benfaber

If you are measuring ambient levels that are clearly wrong, that suggests an incorrect calibration. Please make sure that your units are correct for the input channel and try calibrating again. You will want to perform your calibration on the input channel, not on the input device. In this case, it may not matter what your input device units are (FS or V), since the channel calibration will account for either case. (In other words, there's no need to calibrate the input device unless you need to know the input voltage sensitivity.)

If you see an input gain control, make sure that you don't change the gain after you calibrate. Otherwise, you will need to calibrate again for the new input gain.

If that doesn't correct the issue, it would be helpful if you would provide some additional details. How are you connecting the i436 to the MacBook Pro? In the I/O Configuration menu, how is your input device identified (e.g. External Microphone)?

crawford

On the Mac, the i436 is plugged directly into the headphone TRRS jack. The manufacturer calibrated sensitivity is 9.1 mV/Pa. The input source is external microphone. CH1 units are Pa and device units are FS. The gain is set at -24 dB and has never been adjusted.

On the iphone, the i437L is plugged directly into the lightning port. Input source listed as headset microphone. Device units are FS and gain is "mid". Input channel 1 units are Pa and manufacturer calibrated device sensitivity is -24 dBFS.

So what number do I plug into the input Pa/FS sensitivity box on the calibration screen for each device? I don't know how to determine FS of either device so I am flying a bit clueless here. Thanks.

benfaber

Your units are set up just fine (Pa/FS). FS stands for 'full-scale' and is just a relative value that allows us to convert real-world (analog) values to (digital) values that the software can use.

Since you have your own calibrator, you can ignore the sensitivity provided by the manufacturer. In the input channel calibration menu, you can calibrate your microphone directly by entering the sound level produced by your calibrator and tapping on the Calibrate button while your mic is inserted into the running calibrator.

It's all explained, here: How do I calibrate my microphone with SignalScope or SoundMeter?

If you have questions about the tutorial, feel free to ask.

crawford

I had previously done just that dozens of times with no success. This time, with each device, it worked and the two devices are the same. Go figure! Obviously I did something different this time. Thank you.

benfaber

Glad it's working for you!