A neutral, all-purpose capsule used in a number of mics. Small dip at 2KHz from BM-800 headbasket.

The brass-colored capsule sold everywhere. Fairly flat with a 10KHz rise and little air above that.

Mystery 34mm capsule with brass covers front and back. Warm with a presence peak and little “air.”

Works well for male “big boy radio announcer” voice. Removing the covers makes little difference.

An experimental capsule from Mic-Parts. Ex-OEM, brittle and screechy. I modified mine for a broader, lower HF peak. They still aren’t flat, but they are magic on certain acoustic stringed instruments.

These are a few large, interesting electrets. A capsule isn’t necessarily junk just because it’s an electret.

Joe Keichline reminded me I should include a footnote that my measurements are not comparable to those made in anechoic chambers. The closet where I measure is tiny. I place the mics and speaker 10 inches (25cm) apart so direct sound from the speaker overrides room reflections. For cardioids, proximity effect causes a bass boost. The bass rise you see here is mostly proximity effect. But mics are often used up close in studio work, and some idea how much proximity one exhibits is useful to know. Notice that the CM-012 omnidirectional doesn’t have that rise. Also, my 5” Tannoy speaker has little output below 45Hz, so anything below 50 is random noise and should be ignored.