Here is the relevant data
The setup for this experiment was a Shure SM57 dynamic microphone routed into a Magneto Audio Labs VariOhm, a variable load impedance device, which was then routed into a Focusrite Saffire Pro 14. Room EQ Wizard was used to collect the data.
The purpose of my experiment was to explore the effects of load impedance on a variety of microphones. To this end, I have also included the results of the experiment using an AKG C414 B-XLS as well.
According to impedance bridging principles, optimal voltage transfer is achieved when the load impedance is roughly ten times larger than the source impedance. The results of my experiment, however, have proven me otherwise. Ideally, the voltage of the microphones at the output of the signal chain will decrease at each reduction of load impedance, but instead we see a rise in voltage up to 600 Ohms, and then a significant reduction in voltage at impedances lower than 600.
Is my understanding of impedance bridging principles wrong or is the experiment flawed?