Engineering Brief
Phantom Powering the Modern Condenser Microphone Part II: The Effects of Load Impedance on Microphone Performance
AES Convention 131 · Paper 19 · October 2011
Abstract
This paper builds on topics discussed in the previous AES paper “Phantom Powering the Modern Condenser Microphone: A Practical Look at Conditions for Optimized Performance.” It is not uncommon for microphone manufacturers to measure performance specifications using open load conditions. However, in application microphones are connected to mixing consoles that have much lower input impedances. These operating conditions can affect microphone performance and cause measurements to deviate from published open load conditions. During the previous investigation, changes were seen in several relevant microphone measurements as load impedance was changed. These observations prompted a more in-depth investigation into the effects of load impedance on microphone performance. The specific performance parameters investigated were: sensitivity, self-noise, current consumption, dynamic range, maximum sound pressure level (max SPL), signal to noise ratio (SNR) and frequency response.
