Re: What a Parrot Brained Fuckwit


In article <4LWdnZ2dnZ1N2JjPnZ2dnTGwbd-dnZ2dRVn-052dnZ0@xxxxxxxxxxx> gizzledgeezer@xxxxxxxxxxx writes:

> Phil, if you're going to jump down peoples' throats, at least get your
> technical act together.
>
> The amp in a condenser mic does not amplify the capsule's power level --
> it's a voltage amplifier.

Actually, Phil does sort of have his act together on this, as usual,
but as usual, he's changed the subject so that he can argue symantics
rather than technical facts.

The electronics in a condenser mic actually takes a very high
impedance current source (several megohms) and makes it useful. It
doesn't need to amplify the voltage because there's plenty of voltage,
but it does need to provide an output from the mic's connector that's
at somewhere around the capsule's AC voltage, but at an impedance low
enough so that it can be connected to a useful load.

So, in the process of converting impedance, it's really amplifying
power, just like a power amplififer that drives a speaker from a
console line output. The input to what we in the trade conventionally
call a "power amplifier" might be 20 volts out of the console, but
from a source that can deliver relatively little power, so it can't
drive the low impedance load of a loudspeaker. The output voltage of
the power amplifier may be on the same order as the input, but because
it can drive a low impedance load, it's useful for driving a speaker.
20 volts from the console output into the amplifier's 10,000 ohm input
impedance is 0.04 watts. 20 volts into an 8 ohm loudspeaker from the
power amplifier's output is 50 watts.

The trick to the quiz is the context. "Preamplifer" is the term that
we use for a box (or functional box in a mixing console) that performs
a specific function. In the audio community, it's not a generic term.

Phil phailed, but he managed to correctly describe something
different.



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