Reasons to use a Moving Coil Mic

Moving coil microphones are often called "dynamic" microphones, which they are, but Dynamic is a family name. Ribbon mics are also dynamic microphones, even though no one really calls them that. In this brief thing, I'll use dynamic and moving coil somewhat interchangeably. If you're a stickler for correctness in terminology consider this your trigger warning.

Aside from the usual "Moving coil microphones are more rugged and harder to break," here are reasons why you might choose a moving coil mic in a session:

Need Less Leakage? Use a Moving Coil

Cutting a vocal in a crappy room? Use a cardioid dynamic instead of a cardioid condenser. Why?

Moving Coil mics are a diaphragm pushing a coil of wire: it's heavy and not particularly sensitive to quieter sounds. A condenser diaphragm is super light and highly sensitive. It picks up quiet sounds a lot easier, while a moving coil mic is sorta deaf to quiet stuff.

Room sound, and reverb, and leakage are usually quiet. Do you see where this is going?

Yep - the dynamic (moving coil) microphone won't pick up anywhere as much leakage as the condenser, and what it does pick up will be quieter in comparison to the direct sound (the sound you want to pick up). The net result is the track cut with the moving coil mic will sound dryer and will be easier to mix.

Boring sounding voice or Instrument? Use a Dynamic

Condenser mics tend to have rather flat frequency response with maybe a slight lift in the highs. Dynamics tend to roll off the top end a bit, and unless the mic was carefully designed, the frequency response is strange and anything but even. To me, most of them sound more gutsy and raw. To be fair, there are things like the RE-20, the AKG D224e, and the Sennheiser 441 that are as smooth as any good condenser.

A condenser on a boring or typical sounding source will give you a nice, clear recording of a boring or typical sounding source. A dynamic mic, though, will add some frequency response quirks and oddness, and that can really help to make something more interesting to listen to. Got a boring-ass singer? Stick an SM-57 in front of them and see what you get.

Moving Coil mics are compressors!

Because the diaphragm/coil assembly is on the heavy side, there's a bit of inertia to it. And that means it tends to roll off fast transients a bit. Put a moving coil on a ride cymbal and you'll hear that the "ting" becomes a "shwing." The compression of the transient is purely mechanical: there is no threshold that has to be exceeded, so the attack time is infinitely fast.

This is pretty subtle stuff, but "mic compression" with dynamic can tame a spitty sounding vocal. Elvis Costello used to use an SM-57 in the studio because of this. Also they didn't want him filling up U-67s with drool.

I love using moving coils for hand percussion because of mic compression. Tambourines recorded on a condenser are so sharp they cut your head off, and the transient is so much louder than the jingle that it becomes very hard to sit it properly in the mix. Use a dynamic and the transient gets blunted back and the jingles come up. Ditto for congas, bells, berimbau, claps - anything people are smacking around.

I hear some of you complaining, "But it will roll off the high-end!" Yes. That isn't always a bad thing. Not everything deserves to be airy in a mix. Yes, if you're making a percussion record, you want that air up there for the percussion. But if it's a vocal record, reserve that upper space for the vocals, or whatever else might be driving the recording. You don't need conga overtones competing with a piano or acoustic guitar for real estate above 10kHz.

So there you go.