The speaker is comparing different Lavalier microphones and their sound quality. They are testing the microphones in a quiet studio with some background noise. The first microphone is the PUI-5024L capsule, which has good sensitivity and signal-to-noise ratio. The treble drops off at around 15,000 Hz. It is powered by a 48 volt phantom power and outputs sound in positive phase. The second example is the same microphone capsule, but wired into a 3.5 mm jack, which outputs sound in negative phase. When the phase is inverted, it sounds similar to the first microphone.
In this session I'm going to take a look at various Lavalier microphones and Lavalier microphone capsules in order that we can compare the sound. The microphones are set in a stand in free air, 15 centimetres in front of my mouth. We're in a fairly quiet, well-damped studio, although there is some noise from machinery outside and a refrigerator on the floor below. The recordings are being made into a Sound Devices MixPre-3. Now, this first microphone is the PUI-5024L capsule, which I've mounted in a metal housing.
It has a quoted sensitivity of minus 24 dB and a very good signal-to-noise ratio of 80 dB. It has quite a good extended base, although the treble drops off fairly sharply at about 15,000 Hz. This microphone being fed through a 48 volt phantom power via an XLR, which has a capacitor and resistor built in to drop the voltage to 5 volts. In this configuration, this microphone outputs the sound in positive phase. And the next example is the same microphone capsule, the PUI-5024L, but this time it's wired into a 3.5 mm jack, which is plugged into the Sound Devices Mixer and is being fed by the standard plug-in power from the mixer.
Now, you'll hear that this sounds quite different, because this microphone outputs the sound in negative phase. So, if I now switch that on the mixer from the normal input phase, which is in fact negative from this configuration, to inverted, you'll now hear that the sound has changed. And this, in fact, has been inverted to a positive phase signal, which sounds very much like the same capsule when it's fed through the XLR 48 volt phantom power system.
So, let me just swap that back so that you can hear the similarity between the two. So, this is now the 48 volt powered version of the same capsule, the 5024L, and that sounds very similar to the 3.5 jack version, which has had its phase inverted.