Arny Krueger wrote:

http://www.cadmics.com/pdf_files/e100_manual.pdf
the schematic is on page 4.

Thanks for posting the link. The CAD schematic doesn't seem to show
the actual front end of the microphone circuit at all. It shows the
pad switch as a feedback control later on in the circuit. Weird.


I'll leave it to David to support his claim... The pad is close to the
input, but not exactly at the input.

Furthermore, I see some advantage to attenuating at the input to the
mic electronics, if clipping in those electronics is the concern.

I agree--in most types of condenser microphone, the capsule can handle
far higher sound pressure levels without audible distortion than the
electronics of the microphone can. When the SPL exceeds the amplifier's
capabilities, a pad at the input of the amplifier is the right choice.

But that isn't the usual situation, and it's certainly not the case that
the original poster has. He's trying to feed the signal from a condenser
microphone into an input that was designed for a dynamic microphone, and
he's getting input overload.

That overload _could_ be avoided by using an attenuator between the
capsule and the microphone's electronics, and the original poster
proposed to do that. OK, it's useful as a test--it shows whether lower
signal levels going into the recorder can solve the problem or not. But
when input overload in the _preamp_ is the problem and the mike itself
isn't anywhere near being overloaded by its capsule, then that's not a
good choice, as compared with a resistive pad in-line at the preamp input.


The point is made however, that using internal and external pads can
have vastly different results when you don't know for sure at the
moment where the clipping is coming from (i.e., the real world).

And we agree completely about that, as we probably ultimately do about
all the other points as well. This message isn't meant as an argument
with you, but just as a way to spell out a thought process for how to
decide what to do in this general type of situation.

My suggestions would be [a] know the maximum SPL that each of your mikes
can handle, and only use their built-in pads when there's a likelihood
of exceeding that range; [b] bring in-line resistive pads (15 - 25 dB)
to all location recordings, and use them at the first threat of overload;
[c] if using the resistive pad doesn't help you, then maybe the microphone
really is being overloaded, in which case using its built-in attenuator
may make sense; [d] if your microphone seems unable to handle its rated
maximum SPL without clipping, check your phantom power supply (or better
yet, do that beforehand ...).

[d] is quite possibly an issue in this case, too. CAD Equiteks require
8 (!) mA per microphone--an amount of current which falls just within
the IEC standard, and which relatively few phantom power supplies in my
experience can offer. I mean, Schoeps mikes take only half that much
current, and even they run into problems with phantom supplies at times.

P.S.: The original poster lives in my neighborhood, as it turns out;
we're currently exchanging phone messages and trying to speak and/or
meet in person.