Review on 🔇 Shure A15AS Switchable Attenuator (15, 20, 25 dB) with Phantom Power Pass-through by David Tison

This robust 3-position damper can provide "simplex" phantom power. Designed for low-impedance microphones (I measured the attenuation impedance (1 kHz): Zin 1000 ohms on the female side and Zo 54. 200 ohms on the male side, depending on the range). Shure did not list the impedances on their website. This assumes a low impedance source (most modern condenser microphones) and a load impedance of a few hundred ohms or more for nominal attenuation. Pin 1 is connected to the body at both ends (good). The label indicates that the device was made in Mexico. Impedance was measured with an NTI Minirator Pro.