The Loudest Thing At The Capsule Always Wins

My end of this business is often driven by mythologies and half-truths.

“Class-A watts are louder!” (No. A watt is an SI unit of measure. You either have a certain amount of energy being dissipated, or you don’t.)

“Clipping any amplifier will destroy a connected loudspeaker.” (Sorry – incorrect. Clipping in itself is fine, though potentially ugly sounding. The problem is too much power, whether the red lights are illuminated or not.)

“You need a traditional kick-drum mic to capture a kick-drum.” (I’ve been proving this wrong on a weekly basis for quite a while. Tossing a beat-up MXL 990 inside in a kick sounds just fine, and saves me a little bit of floor space.)

Anyway.

Microphones, being somewhat mysterious fauna, are no strangers to being misunderstood. There are many specifications attached to them, and if you don’t know what they mean in context, it’s easy to misinterpret what’s going on.

A big, sort of “omnibus” myth is that microphones have some sort of magical ability to discriminate between what you want them to pick up and everything else. This myth manifests in such (understandable but spurious) notions like mics with higher sensitivity being necessary for quiet singers. The idea is that higher sensitivity allows the mic to “reach” farther from itself, and grab the sound of the vocalist. Also, the thought includes a guess that feedback might be reduced, because less post-mic gain is applied.

Like I said, this is understandable, but inaccurate.

Let me reiterate the title of this article: The loudest thing at the capsule always wins.

There, is, of course, nuance to this that bears digging into.

A Dumb Sensor Of Pressure

Microphones don’t have pattern-matching and synthesizing brains like we do. For all the sophistication in their construction, mics are rock-stupid devices which translate pressure events into electrical signals. They don’t know what you want and what you don’t want – they are only “aware” of sound-pressure changes.

If the sound-pressure change is what you want to pick up, that’s great. If not, too bad.

A mic with higher sensitivity relative to another model of transducer is not somehow able to “reach out and grab” a quiet source. All that the greater sensitivity means is that, for a given amount of sound-pressure, the mic has more output voltage. Without anything else going on in the room, the greater output might trick you into believing that the mic will give you more of the singer – but that’s not the case. When everything else on deck kicks in, the singer will be just as washed out as ever. Your problem is proportion, not absolute output level.

This also connects to the feedback problem. Feedback depends on the TOTAL gain through the “loop,” not just the gain from mic pres and consoles. Higher sensitivity means that (if you change nothing), the total gain through the loop is increased. Unless the high-sensitivity mic has a more feedback-resistant design overall, you will actually have a greater tendency towards feedback…until you reduce the post-mic gain to compensate for the increased sensitivity.

Of course, multiple things can change when you swap out a microphone. A microphone may, for example, have both greater sensitivity AND a tighter polar pattern in comparison to another unit. This can make the mic seem like it can “reach farther,” because the capsule is less sensitive at certain angles than others. However, move things around until an undesired noisemaker is at the same angle to the capsule as the thing you want to hear, and you’ll see that your problem comes roaring back.

(This is not to say that a tighter pattern can’t be helpful in working through certain issues. It’s merely to say that it doesn’t magically make the mic discriminatory for sounds arriving at the same angle.)

So, What Does It All Mean?

The upshot for you is that what you want to pick up should be – from the mic’s perspective – VERY loud in comparison to everything else. If it isn’t, then the mic is just helping you amplify a bunch of what you don’t want.

If, at the mic capsule, a singer is being almost totally drowned by a guitar amp, cranking up the mic through the monitors isn’t really going to help. The signal coming off the mic is a little bit of singer and a lot of amplifier, which means that more monitor means a little more vocal and a lot more of the guitar rig. And that very likely makes the problem even worse for the vocalist.

On more than one occasion, I have worked with bands where I was really on the gas with the vocal mics, and I was hammering the PA limiter. I was NOT hitting the limiter with actual vocal. The gain reduction indicator was perfectly in time…with the snare drum. (!) There was nothing wrong with the PA, or the equalization of the PA, or the mic choice. The problem was that the singers couldn’t “hang” with a rock drummer, and the rock drummer wouldn’t make space for the vocalists.

On another occasion, a drummer specifically asked me to hang some overheads above his kit. He also had me dial up a TON of the rest of the band in his monitors. Midway through the show, I soloed up the overheads into my headphones. I certainly heard some drums, but I heard at least as much of his monitor mix bleeding into those overheads.

The overheads were not something I wanted to put into the FOH mix – they would just be making the rest of the band louder, not bringing the drums out more.

The loudest thing at the capsule wins. Good mics are a fine investment, but some sort of inherent imbalance that the mic can “hear” requires fixing at the source. You have to make sure that mic is getting what you want it to get, because you’re the one with the brain.

  • NigelMusicNZ

    Totally true. I play a lot with acoustic instruments (and musicians). Biggest problem is when a muso wants a ton of their own instrument in their foldback – guess what, feedback is a killer.

  • Damn straight!