Re: Playing Straight through the PA

[Mike Curtis <wd6ehr@xxxxxxxxxx>]

<Crystal mic with XLR connector>

Seeing that Shaker makes a crystal mic with XLR connector (their "XLR"
model), you'd think this would work fine when plugged into the PA.  Speaking
technically, this is a design flaw on Shakers part.  Crystal mics and XLR
connectors should never be paired without proper impedance matching, which
is not done on the Shaker XLR model.  XLR connectors are standardized for
low impedance balanced line.  On the PA mixing board, XLRs always terminate
into low impedance, theoretically 600 ohms but typically something on the
order of 2k.

Crystal mics are high impedance, well into the megohm range.  They sound
very thin and tinny when terminated into low impedance, with a sound quality
not at all unlike fingernails on the blackboard.  If you use a crystal mic
with XLR connector, you will get a much better sound if you terminate into a
preamp with high impedance input.  A transformer might be another option,
although I've never tried a transformer with a crystal mic.  One megohm is
generally considered a minimum terminating impedance for crystal elements.

For termination directly into the console, a low impedance dynamic element
would provide better sound quality.  Shakers "Dyno-mic" dynamic has a
high-Z/low-Z option and XLR connector.


 -- mike