What are the recommended audio interfaces and measurement microphones for use with Smaart?
Smaart will work with any audio I-O device that uses Wav/WDM (Windows), ASIO (Windows) or CoreAudio (MacOS) device drivers, so long as those drivers are compatible with the OS version you are running. It is up to the hardware manufacturer to ensure that the device is compatible with the most recent version of Windows or MacOS, so make sure you check their driver information when purchasing the device.
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Regardless of the operating system, make sure the audio interface has enough In and Out channels for the measurement set up you will be using. If you have a complex, interconnected system, we recommend researching Dante Virtual Soundcard.
Determining what measurement microphone to use depends on the type of measurements you will be making. If you are measuring SPL at (high) show levels, one of the most important things to consider is if the measurement microphone's maximum output voltage exceeds the audio interfaces' maximum input level rating at minimum gain (these specifications are provided by most manufacturers).
The first thing to look at is the audio interface's max input level, which is typically given in dBu (1dBu = 0.775 vRMS). Exceeding this level will clip the interface, causing an "OVERLOAD" message to appear within Smaart on any SPL meters for the input:
The OVERLOAD message occurs when the interface is clipped, not the mic itself
From here, you'll have to determine how much voltage your measurement microphone provides at its Max SPL reading. As a general rule of thumb, you can multiply the mic’s sensitivity in mV/Pa by 200 to determine its voltage output at 140 dB SPL, our target for concert-level SPL measurement. For example, if your microphone has a sensitivity of 34 mV/Pa, at 140 dB SPL it will produce a voltage of 6.8Vrms or +19dBu. As long as that number (in this case +19dBu) is less than the preamp’s maximum input level at minimum gain, you can be confident that the interface can accommodate signal peaks without overloading.
While this might seem like a bit of unnecessary math, the main takeaway is that low-sensitivity (< 7mV/Pa) microphones are optimal for high-level SPL measurements whereas high-sensitivity (10mV/Pa or more) are not. Lower sensitivities provide a lower voltage at Max SPL than higher ones, allowing them to send higher levels to an interface without clipping it. High sensitivity mics do have their place -- since they are more sensitive to small changes in the environment, they are perfect for low SPL environments where overcoming the electronic noise floor is important. A great example of a low-sensitivity mic would be the iSEMcon EMX-7150 and a high sensitivity mic would be anything by Earthworks (such as the M23R).
To make this even easier, we've added tags such as "Lo-Sens", "Hi-Sens", and "SPL" to the measurement microphones on our online store to help you determine which mic to choose at a glance. Click here for a description of each tag and what they mean.
Nevertheless, if you still are having trouble determining what will be best for the job, please send a support ticket and we would be happy to help.
If you have any questions about how Windows' WAVE driver interacts with Smaart, please go here to the video on our YouTube.
To Contact Rational Acoustics Support:
Submit a Ticket Here or Email us at Support@RationalAcoustics.com.