DIY Electromagnetic Listening Devices

Electromagnetic pickups give us the ability to listen in to a world of sound that is beyond our normal range of hearing, and their simplicity make them an excellent candidate for the DIY enthusiast. I have experimented with a few such options, as they are listed here:

The most basic electromagnetic listening device can be constructed by soldering the two leads of an off-the-shelf inductor to the signal and ground leads of any audio cable. In this case I used a cheap 10mH radial inductor, which produces clear results but only at short range and with no stereo component.

Mono Inductor Coil

Stereo Inductor Coil

The same simple coils can be wired together to a stereo audio cable to create a stereo pickup. This can lend a nice stereo image depending on the source, and opens up the potential for interesting pass-by or whoosh sound effects. Its extremely small footprint makes it a natural companion to small handheld recorders with a 3.5mm stereo input, and mine has been a consistent part of my every-day-carry field recording kit for quite some time now.

In an attempt to extend the range of my electromagnetic listening kit, I went looking for larger coils. LOM makes the Priezor, a handheld antenna that looks and sounds beautiful but like most LOM products is consistently out of stock. Using this model by azzajess that mimics the form factor of the Priezor, I 3D printed a housing and hand wrapped it with 28 AWG enameled copper wire. With about 200 wraps the range is somewhat better than the smaller inductor coils, but the improvement is not quite as dramatic as I had hoped. However the timbre of the recordings is also quite different from the smaller units and so makes a useful addition to my kit nonetheless.

LOM Priezor Clone