In article 6ZJEh.8700$tA1.2257@trndny02,
Spin wrote:
The electret element in question is 400 ohms imp & it was plugged into
the input of a 600 ohm imp computer sound card. Recording my speech i
noticed that it lacked "highs". I then replaced the above with a 2k ohm
imp element & there was a vast improvement. The improvement consisted
of a higher freq response & a dramatic increase in output (volume).
What baffles me is, i thought that by matching the mic & sound card
with similar impedance that i would get better efficiency? It appears
that my computer sound card (600 ohm input ) works better with a 2k
ohm mic than a 400 ohm mic! By the way the sound card provided the
power for both mics. Any comments concerning the above would be
appreciated.

A nominal 600 ohm input won't be 600 ohms but somewhat higher. At one
time, about 1.2k was the norm for a nominal 600 ohm mic. Which are usually
about 300 ohms. ;-) A higher input impedance shouldn't effect frequency
response but might make the noise figures worse. However, too low an input
impedance will result in a bass loss. Which might sound like a treble gain.

--
*Constipated People Don't Give A Crap*

Dave Plowman London SW
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