Dave J wrote:
> I'm confused. I thought all XLR mics were low-Z,
> but now I'm not sure.
Most, but not all. XLR is a connector, not an
interface standard. With an XLR typically pins
2 and 3 are the AC (audio) circuit and they should
present (and accept, for the preamp) same impedance,
which makes it a balanced circuit.
But you can wire an unbalanced circuit to an XLR
(typically shorting pin 3 to pin 1, which is the shield.
Balanced or unbalanced is independent of low-Z or high-Z
but usually low-Z mice have XLRs, and high-Z sources,
like some mics, and guitar/bass electromagnetic pickups
are high-Z, and often have a two conductor co-axial
connector like a 1/4" phono plug.
> Is 1000 ohms low-Z or high-Z ??? Thanks.
1000 Ohms is approaching high-Z. Low-Z is
typically 300-600 Ohms, and high-Z is typically
2000-10,000 Ohms. And there are very high-Z
audio sources, for example piezoelectric pickups,
which might be a megOhm or more.
In general, to avoid distortion from "shorting out"
the source, you want the preamp "sink" impedance to
much larger than the source impediance.
So a low-Z mic into a high-Z preamp input is mostly OK,
although some low-Z mics need loading to sound their best.
Hope that helps and doesn't confuse you more.
If you've got more questions, ask.