AW: mic recommendations; champagne recording on a beer budget

["Rainer Thelonius Balthasar Straschill" <rs@moinlabs.de>]

> Considering the cost (95 cents for each mic element, $1.95 
> for a good XLR jack, and a few pennies for wire, solder, and 
> a straw), it was worth the time to check a couple of 
> elements.  Especially since you were getting a $400 mic for 
> less than $5.

Still, I wouldn't want to use the "thing" for some professional
applications, and that for two reasons:

        * impedance of a condenser mic capsule
        * symmetrical signal

What is that? The microphone signal you get on a mic cable from your 
typical
studio/stage microphone is a symmetrical signal with a source impedance of
around 200 Ohms (frequency-dependant though). This is not what you get from
your condenser capsule. The condenser capsules (being basically condensers,
as the name implies) have an extremely high DC and low-frequency impedance.
To get that into a signal good for using with your standard situation, you
need to make the signal symmetrical and change the impedance to ~200 Ohms.
How do you do that? Either with a transformer or with an active circuitry.
So you have to take these into your calculation as well.

One thing about using a RTA to compare things. The fact that two things 
that
have the same (complex) frequency response are identical in
signal-processing terms is only true for LTA (linear, time-invariant)
devices, which some (esp. tube) mics are definitely not. The fact that two
things that look identical on your typical RTA have the same frequency
response is only true if by some strange case of luck they happen to have
the same phase response.

So careful what you do with (and what you deduct from) your metrology

        Rainer