Re impedence matching, for what it's worth I've successfully used a Tandy
impedance adapter with a Sennheiser ME67 mic going into a Sony Walkman WMD6=
C
cassette recorder, (the recorder is ancient but I carry it on longer trips
as a backup for DAT). The sound to the walkman is definitely louder using
the adapter, and it also serves to connect XLR mic to the mini-plug walkman=
.
The impedance adapter brand was 'Archer' "Lo-Z balanced to Hi-Z unbalanced"
274-016. Maybe they don't make them any more, but they were relatively
inexpensive. The transformer had female XLR to quarter inch pin so I neede=
d
to get an inline RCA adapter, then made up a lead RCA to minijack. Works
with stereo too, using 2 adapters. The cassette recordings were definitely
better when using the impedance adapter, maybe 6-10 db gain.
Vicki Powys
Australia
on 10/6/06 3:54 PM, oryoki2000 at wrote:
> I have read conflicting points of view about impedance matching:
>
> 1. Matching the impedance of the mic output to that of the recorder
> input reduces the power lost when a signal is transmitted. The result
> is a louder recording without needing to boost the signal through the
> recorder's preamp. For a brief discussion, see:
>
> http://hyperphysics.phy-astr.gsu.edu/hbase/audio/imped.html#c4
>
> 2. Modern transistor designs (meaning any audio device made since the
> 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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> "Microphones are not ears,
> Loudspeakers are not birds,
> A listening room is not nature."
> Klas Strandberg
> Yahoo! Groups Links
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