The miniDSP PMIK-1 is the perfect pocketable companion to audio analysis programs running on your tablet or even your smartphone. In this application note we will show you how to set up your PMIK-1 with the SignalScope Pro app from Faber Acoustical, running on an Apple iPad.

Please note: miniDSP cannot provide support for third-party applications or hardware. This app note shows you how to set up the miniDSP PMIK-1 to use with SignalScope Pro but other functions of the Apple iPad and SignalScope Pro are beyond the scope of miniDSP support.

1. Get your calibration file [Top]

Go to the PMIK-1 page and enter your microphone's serial number. It is in the form xxx-yyyy and labeled on the microphone.

The calibration file ensures that your microphone is as accurate as possible. Each microphone has a unique calibration file, which is why the serial number must be entered.

*1000Hz	-32.1	
20.00	-3.9
20.55	-3.6
21.11	-3.2

2. Get connected [Top]

The PMIK-1 simply plugs into the headphone jack of the iPad. The microphone body is oriented at 90 degrees to the plug, which makes it easy to use your iPad in landscape mode and point the microphone towards the sound source:

PMIK-1 with iPad running SignalScope Pro

As suggested by the photograph, we recommend that for the most reliable and repeatable measurement results, the included wind/pop filter be removed from the PMIK-1. If the pop filter is used, be aware that the response above 10 kHz will read up to a few dB low.

To generate audio output from the iPad for the purpose of measuring system response, connect a cable from the rear of the PMIK-1 to the system being tested. At the PMIK-1 end, the cable will have a 3.5mm stereo jack. A 3.5mm to RCA socket adapter is included with the PMIK-1 to make it easy to use regular RCA cables to connect to the system.

3. Calibrate [Top]

If you haven't already, install the SignalScope Pro program on your iPad from the App Store.

Then open the I/O Configuration screen by tapping on the "Microphone" icon at the top left of the screen. Change the Device Units to FS and set Gain to Low:

PMIK-1 with SignalScope Pro on iPad

Then tap on Input Channels. If under All Channels it does not say "Units (Pa)", tap on "Units" and select Pa from the list and then tap on Back.

PMIK-1 with SignalScope Pro on iPad

You will need to use iTunes to copy the downloaded file to the correct location on the iPad. Use the iTunes Apps window to locate SignalScope Pro, and copy the folder Frequency_Response_Data to your computer. Copy the calibration file into the downloaded folder, then in iTunes, upload the whole folder back to the iPad.

Tap on Frequency Response Data, then Load FR Data From File, and select the uploaded file. The lower part of the screen will fill with the file preview. On that screen, tap on Load Frequency Response Data. You will get a confirmation dialog and the calibration curve of the PMIK-1 will be displayed:

PMIK-1 with SignalScope Pro on iPad

Then tap on Calibrate. Unfortunately, because different devices will have different sensitivity on the microphone input, it is impossible to provide a standard adjustment to get correct SPL readings. You will need to use an external sound source with a known SPL. With our iPad mini, we used the value 23 in Input Sensitivity, so you could enter that as an approximation if you wish.

PMIK-1 with SignalScope Pro on iPad

4. Measure! [Top]

You can now start to measure! We've covered the specifics in our app note for the UMIK-1 with SignalScope Pro, so please jump to that app note to do more with SignalScope Pro and the PMIK-1. Here are a couple of examples.

SignalScope FFT display from PMIK-1

SignalScope oscilloscope display from PMIK-1


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