1980's) use voltage transfer rather than power transfer. Voltage
transfer is actually improved when there is a large difference in
impedance between mic and recorder. So matching impedance will reduce
the volume of a recording.
http://www.shure.com/ProAudio/Products/us_pro_ea_imepdance
Perhaps these two points of view are not mutually exclusive. I have
little understanding of the physics and electrical engineering
principles involved here. In my limited experience, however, I find
impedance matching to be a valuable way to gain some volume without
adding extra preamp noise.
The impedance of my Sennheiser ME62 is 200 ohms. The impedance of a
Sony minidisc recorder is about 2000? 5000? ohms. (If I remember
correctly, Sharp minidiscs have a mic input with 10,000 ohm
impedance.) When I use a Shure A96f impedance matching transformer
($40) to raise the ME62 output to 2500 ohms, the minidisc records a
considerably louder signal.
A member of this list had similar results by employing the Hosa
MIT-156 impedance transformer ($20). This device is also calibrated
for 600 ohm mic output and 2500 ohm recorder input.
Both cables have the added advantage of having an XLR female connector
on the mic end, and a 3.5mm male connector on the recorder end. So
either cable will let me connect a pro mic to the minidisc recorder.
--oryoki
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