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Huh!? (Condenser Power) Condenser Microphones
Old 5th January 2004
  #1
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Huh!? (Condenser Power)

Hey.

Whilst doing some research on the difference between Electrets and Condensers I came across this

Quote:
Two years ago this was a pretty good generalization, but the problem is that the
market is currently being flooded with externally-polarized large diaphragm
mikes in the dirt-cheap range. (Most of them use the phantom to polarize
the capsule directly at 48V or so, which is a really lousy idea if you ask
me, but cheap to make).
--scott
Can someone explain it to me in laymans terms? Why is polarising the capsule directly at 48V a bad idea? Which mics do this and which don't? And how are the ones that don't actually powered?
Old 5th January 2004
  #2
Lives for gear
 

Normally you need to peek inside. Most Neumann and AKG mics use a DC to DC converter to take the 48 volts (usually less because of the power feed resistors) and convert it to around 60 volts for the capsule.

There is nothing really inherently bad with polarizing the capsule with direct filtered phantom power. You get a lower output level than with a 60 volt polarization voltage. Normally you can get about 40 volts to polarize the capsule without the DC-DC converter in there.

There are good sounding electrets, too. Many of the new AKG Cx000 type mics are electret, and they sound pretty good. Even the new C451B is electret, I wouldn't have known from the sound. It has a lot to do with the tuning of the capsule element and the design of the mic. Plus AKG's electret mic does not use a leaky insulator bias arrangement, they use a real bias resistor. A lot of measurement mics (B+K) are electrets, and they're pretty good.

Many far-east LDC's do power the capsule in the 'cheap' way but that's not the cause of the nasty sound a lot of those mics have.

The high frequency response measured and unfiltered is very peaky, where the published graph shows a smooth presence peak, the unfiltered frequency response shows +/- 10 to 15 dB peaks and valleys that average out to the published graph. I did this on my Apex 430, and also on the Apex 460. The 430 is a solid-state mic with the 'cheap' phantom powering. The 460 is a tube condensor with around 60 volt polarizing voltage. Both sounded crummy and have a funny frequency response up there.

I replaced the capsule in the 430 with an AKG C12VR capsule and it sounded much better. Same polarization voltage. Did the same with the Apex 460 and it sounds pretty darned good to my ears.

-Dale
Old 5th January 2004
  #3
Gear Addict
 

I don't know anything about mic powering, but i don't think the AKG C1000 mics sound very good. Low output and high noise, for starters, and then there's the sound...

Anyone else know what if anything the powering scheme has to do with the yucky sound of these mics?
Old 6th January 2004
  #4
Lives for gear
 

I have a C1000 too and I don't care for it. It is an electret design, but the sound has more to do with the acoustics. The new C451B has the same powering scheme (electret) but sounds a lot better, so does the C4000.

Here's an experiment: try removing the screen (where you normally put the battery), and see if you find the sound different. Try removing the foam insert from the screen and see if you think that's better or worse. Have you tried the little presence or pattern adjusters? I lost mine so I haven't but since I have enough other mics I don't worry about not using my C1000.
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