Re: USB versus non USB (LDC) mics?


Arny Krueger wrote:

Yes, the USB mics I am aware of provide their own phantom power from the USB
interface.

To be fussy about it, they make whatever power the microphone requires
from the 5V available at the USB port. Phantom power is a specific
powering configuration that carries DC to power the mic over the same
wires as the mic's audio output.

A USB mic *must* include the function of a mic preamp. *Every* mic preamp
worth its salt has an internal gain control. We use mic preamp gain
controls to optimize dynamic range and minimize noise by controlling the
gain of the preamp so that its output is in the desired range.

I know of no USB microphones that control their gain in the same manner as
we commonly control the gain of mic preamps.

I suspect that they use a dedicated chip that has a mic level input on
one end and USB output on the other, so you're not likely to find a
dedicated analog gain chip that serves as a "preamp." But then I've
enver taken one apart either.

The Samson USB mic has a control panel application that has a meter and
gain control, but it doesn't work right (they admit that it's really
just eye candy) and it may be just another handle for the Windows
mixer.

I get a feeling that someday, someone, will do a proper USB or Firewire
microphone with a properly-designed mic preamp and quality converters.
Initially, it will probably be out of the sub-$100 entry-level price range
we often see such products in today. It just hasn't happened yet.

Neumann does a proper AES/EBU microphone, but it costs more than $100.
<g>

.

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