Earlier this autumn I bought a Wildlife Acoustics SM4-mini to use for a long-term nocmig project in North Norfolk. I set this up with a spare fibre glass parabolic reflector that was generously given to me, to improve the range of the microphone. The whole setup was fixed to a garden shed in a coastal village and angled slightly towards the coast and away from nearby trees.
The SM4-mini is pretty compact (approx. 5″ x 6.5″ x 1.5″), runs off 4 AA batteries and takes standard SD cards. The box is rugged and waterproof and has slots and holes for attaching it to things. The setup includes a single microphone but there is a second port to add an optional second microphone for stereo recordings.
One feature I really like is the mobile app used to configure the device. The device broadcasts a Bluetooth signal which provides basic info like how many recordings have been made to date. Open the box and press the pair button and you connect your mobile app to the device to control all the settings. It is highly customisable. For example, you can configure your own on/off cycles, or allow the devise to use sunset and sunrise times as the basis of the routine.
As you’d expect, you can control the sample rate, the length of files and the gain setting. You can also set a delayed start time. On my last deployment I knew the weather was going to be horrendous for a few days so I delated the start until after the bad weather to save on battery/card life.
Given the particular batteries, card and configuration you’ve selected, the app will estimate when the batteries will be depleted and when the memory card will be full.
So what about the recording quality? I think it is pretty good as can be judged from the following recordings:
These are cherry picked interesting examples from my most recent deployment but I think they are representative of the quality the recorder provides. The recorder has run continuously since mid August with no failures or errors. I haven’t done any side-by-side tests of this (with or without the reflector) against other recorders.
I’m very pleased with the device for the following key reasons:
- it’s waterproof
- it’s easily programmed via a nice mobile interface
- it runs autonomously for 3 weeks (on my settings)
- it produces nice clear nocmig recordings
When I retrieve the recorder I will try to make some side-by-side recordings with other equipment.
PS: for anyone considering mounting an SM4-mini in a parabolic reflector, getting the microphone element at the precise focal point of the dish is critical. Without removing the foam windshield of the mic it is hard to know where the mic element is located, but I was told by Wildlife Acoustics that it is 16mm (±1mm) from the outside of the case.