[k0ngo]

> On a different note, why is that (as far as non-expert me knows) that nice mics often have eq settings? Is this not a blatant layer violation?

The low-frequency/subsonic content that this switch will remove often consists of wind noise, pops from talking too close, vibrations from the floor/mic stand, etc. Even if these low frequency noises may be more or less inaudible, they'll contribute to a large signal swing that will decrease the headroom in the following amplifiers. In other words, you won't be able to turn up the gain in the microphone amplifier/mixer as much as you'd want, because the low-frequency but high-amplitude content will make the amplifier clip and distort the sound. Filtering the signal after the mic preamp won't solve the problem, because the preamp (which can provide in the order of 60 dB gain) will be the component that clips. By including a low-cut filter in the head amplifier circuit inside the microphone (the amplifier serves only as a buffer, and usually with unity gain), the disturbing low-frequency noises can be removed before entering the high-gain microphone preamp. You can find the low-cut switch next to the capsule in the U87 schematic [0]. It seems to me that they increase the capsule bias voltage, thus changing the low frequency response by electrostatically tensioning the membrane.

[0] http://recordinghacks.com/images/mic_extras/neumann/U87-sche...

edit: tweaked some things. meta: i'm not very good at commit messages.

[Ericson2314]

Ah needs to be with the mic preamp, ok. Granted there's a lot of inertia in connectors, but has anybody tried to run extra wires in the mic cable to control these things from the both?

[tacos]

As odd as it sounds, microphone cables weren't standardized until 1992. Before then companies did all sorts of stuff.

Here's a Neumann mic from 1952 that could be set remotely. http://recordinghacks.com/microphones/Neumann/M-49

Today it is increasingly common to put the analog stuff as close to the source as possible and remote control it.

[Ericson2314]

What is the standard? I mainly see XLR but I've stared at far more live equipment than recording equipment.

[tacos]

It's XLR. But even then Americans and Europeans couldn't agree on where to stick the three wires.

This is the 1992 document that finally standardized "pin 2 hot" among other minutiae: http://www.aes.org/publications/standards/search.cfm?docID=1...

[Ericson2314]

Interesting, thanks!

[tacos]

For a vocal/voiceover mic loud sounds are not a concern. (The U87 has a pad switch for those cases separate from the proximity/EQ switch.)

The things you mention (vibrations, LF rumble) are typically handled by the highpass on the mic preamp and are in the 75 or 80Hz range. In musical terms, that's 4+ octaves below the 1k proximity rolloff on the mic itself.