Re: was someone here designing a ribbon mic pre-preamp?

"David Satz" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> I wrote:
>
>> The output impedance goes literally off the chart, where the limit
>> of the scale was 1000 Ohms.
>
> Strangely, Google's interface to this newsgroup isn't allowing me to
> reply to Arny Krueger or Scott Dorsey's messages a little further down
> along this thread.  And a message that I'm sure I posted here this
> morning has yet to show it's face, so this one may or may not make it,
> either; I guess we'll see.
>
> What I'd like to point out is that the output impedance curve for the
> SF-1 is not monotonically rising at the low end; rather, it peaks at
> some frequency between 30 and 70 Hz, then descends again so that at
> 20 Hz, it's a mere 700 Ohms (!).  There's no indication of any output
> coupling capacitors there [NB: Arny].

Well that settles that!

> This was an SF-1 that was re-ribboned by Royer to match my other SF-1,
> and somewhere here I do have their resonance frequency written down,
> but unfortunately I can't find it at the moment.  I believe it is
> right in the region of the microphone's highest output impedance,
> however.

Yes this looks more like a bass resonance of a speaker driver. Same basic
physics should relate to both woofer cones and mic diaphragms.