electret v condenser

[buggyboy]

I have a quick question which my googlefu has failed to answer.

Are lav and headset/earset mics all (ok, 99.8%) electret based?

Do you know of any using capacitor-condenser based capsules?

What about gooseneck podium mics?

thanks

[waynehoskins]

Virtually all condenser microphones these days use permanently-polarized electret elements, certainly all that are used in pro audio circles these days. The place to find exceptions is recording studios, where large multi-power supplies for non-permanently-polarized condenser microphones, and the special multi-pin cables to connect them, are practical.

Also, a bit of historical trivia, condenser is the old word for capacitor. Capacitor came into favor somewhere in the late '60s or early '70s, but before then we spoke of condensers -- so if the name hadn't already stuck to microphones, we'd be talking about capacitor microphones.

[buggyboy]

According to my research phantom power was developed to power condenser mics that needed the ~48 volts to polarize the plates. Electrets only need enough power (a few volts) to run their amplifiers. Is that a correct understanding of the situation?

[waynehoskins]

That sounds right. However, as electret elements came into use (and as I recall, they were significantly less expensive), stage microphones with true-capacitor elements became most uncommon.

I do recall reading about one true-capacitor microphone lately. Maybe the AKG C414? I think it was when I was reading up on the history of the 414 that I read that. Some people -- mostly from the studio world -- think a true-capacitor element sounds better, more natural, more transparent, etc. than an electret element, but I doubt the difference would be a deal-breaker for a live stage mic. On the other hand, perhaps once you hear the difference you can't go back.

To the original scope of your question -- headset, lav, gooseneck mics -- I guarantee they're all electret capsules. For one, since headsets and lavs are intended to be plugged into a bodypack transmitter that runs on a small battery, developing enough bias for a true-capacitor microphone while retaining electret compatibility would be problematic. I believe another advantage of electret elements over true-capacitor elements was size, an electret element could be smaller. Since these are miniature-microphone applications, if that's the case true-capacitor microphones are at a disadvantage there was well.

[buggyboy]

One last question in this vein.

Do lav capsules, the part that goes on the tie clip (or on the face), have electronics in them? That is, other than the electret capsule itself.

Any impeadance converters, preamps, etc inside that little lav/headet mic.

(as opposed to electronics in the beltpack).

[Ray A. Rayburn]

Originally Posted by buggyboy

Are lav and headset/earset mics all (ok, 99.8%) electret based?

Yes.

Originally Posted by buggyboy

Do you know of any using capacitor-condenser based capsules?

All electret mics are condenser (capacitor) mics. Not all condenser mics are electrets. An electret based capsule does not need external polarization on order to operate, although the associated impedance converter amplifier still needs power.

When people talk about "true" condenser mics what they really mean is mics using externally polarized condenser capsules.

Originally Posted by buggyboy

What about gooseneck podium mics?

The majority probably are electret types, but dynamics and externally polarized condenser types are not unknown.

[Ray A. Rayburn]

Originally Posted by waynehoskins

Virtually all condenser microphones these days use permanently-polarized electret elements, certainly all that are used in pro audio circles these days.

Externally polarized condenser mics have never gone away, and in recent years have made quite a comeback. There are now quite a few externally polarized condenser mics getting sold for sound reinforcement applications.

Originally Posted by waynehoskins

The place to find exceptions is recording studios, where large multi-power supplies for non-permanently-polarized condenser microphones, and the special multi-pin cables to connect them, are practical.

You appear to be confusing condenser mics that use tube circuitry (and usually externally polarized capsules) with the more generic class of condenser mics with externally polarized capsules. When phantom power was first invented it was used to power condenser mics with externally polarized capsules like the Neumann U87 or the AKG C451E. These days externally polarized capsules are coming back into popularity with mics such as the Superlux S125 (a very nice handheld vocal condenser).

[Ray A. Rayburn]

Originally Posted by buggyboy

Do lav capsules, the part that goes on the tie clip (or on the face), have electronics in them? That is, other than the electret capsule itself.

Any impeadance converters, preamps, etc inside that little lav/headet mic.

(as opposed to electronics in the beltpack).

Yes. The wiring from a condenser capsule (any type) can only be run a few inches without significant losses. Therefore an impedance converter (at least) is placed very close to the capsule, or in many cases actually inside the capsule itself.

[buggyboy]

Thanks Ray, I never got a really good answer to that last question. My research suggested just what you said, that electret mic capsules need some circuitry quite close to capsule... and given what i can see in lav mics, the only place for that circuitry would be in the tie mounted mic head itself.